Different parts of this specification are at different levels of maturity.
This section is non-normative.
The World Wide Web's markup language has always been HTML. HTML was primarily designed as a language for semantically describing scientific documents, although its general design and adaptations over the years has enabled it to be used to describe a number of other types of documents.
The main area that has not been adequately addressed by HTML is a vague subject referred to as Web Applications. This specification attempts to rectify this, while at the same time updating the HTML specifications to address issues raised in the past few years.
This section is non-normative.
This specification is intended for authors of documents and scripts that use the features defined in this specification, and implementors of tools that are intended to conform to this specification, and individuals wishing to establish the correctness of documents or implementations with respect to the requirements of this specification.
This document is probably not suited to readers who do not already have at least a passing familiarity with Web technologies, as in places it sacrifices clarity for precision, and brevity for completeness. More approachable tutorials and authoring guides can provide a gentler introduction to the topic.
In particular, readers should be familiar with the basics of DOM Core and DOM Events before reading this specification. An understanding of Web IDL, HTTP, XML, Unicode, character encodings, JavaScript, and CSS will be helpful in places but is not essential.
This section is non-normative.
This specification is limited to providing a semantic-level markup language and associated semantic-level scripting APIs for authoring accessible pages on the Web ranging from static documents to dynamic applications.
The scope of this specification does not include providing mechanisms for media-specific customization of presentation (although default rendering rules for Web browsers are included at the end of this specification, and several mechanisms for hooking into CSS are provided as part of the language).
The scope of this specification does not include documenting
every HTML or DOM feature supported by Web browsers. Browsers
support many features that are considered to be very bad for
accessibility or that are otherwise inappropriate. For example, the
blink element is clearly presentational and authors
wishing to cause text to blink should instead use CSS.
The scope of this specification is not to describe an entire operating system. In particular, hardware configuration software, image manipulation tools, and applications that users would be expected to use with high-end workstations on a daily basis are out of scope. In terms of applications, this specification is targeted specifically at applications that would be expected to be used by users on an occasional basis, or regularly but from disparate locations, with low CPU requirements. For instance online purchasing systems, searching systems, games (especially multiplayer online games), public telephone books or address books, communications software (e-mail clients, instant messaging clients, discussion software), document editing software, etc.
This section is non-normative.
Work on HTML 5 originally started in late 2003, as a proof of concept to show that it was possible to extend HTML4's forms to provide many of the features that XForms 1.0 introduced, without requiring browsers to implement rendering engines that were incompatible with existing HTML Web pages. At this early stage, while the draft was already publicly available, and input was already being solicited from all sources, the specification was only under Opera Software's copyright.
In early 2004, some of the principles that underlie this effort, as well as an early draft proposal covering just forms-related features, were presented to the W3C jointly by Mozilla and Opera at a workshop discussing the future of Web Applications on the Web. The proposal was rejected on the grounds that the proposal conflicted with the previously chosen direction for the Web's evolution.
Shortly thereafter, Apple, Mozilla, and Opera jointly announced their intent to continue working on the effort. A public mailing list was created, and the drafts were moved to the WHATWG site. The copyright was subsequently amended to be jointly owned by all three vendors, and to allow reuse of the specifications.
In 2006, the W3C expressed interest in the specification, and created a working group chartered to work with the WHATWG on the development of the HTML 5 specifications. The working group opened in 2007. Apple, Mozilla, and Opera allowed the W3C to publish the specifications under the W3C copyright, while keeping versions with the less restrictive license on the WHATWG site.
Since then, both groups have been working together.
This section is non-normative.
It must be admitted that many aspects of HTML appear at first glance to be nonsensical and inconsistent.
HTML, its supporting DOM APIs, as well as many of its supporting technologies, have been developed over a period of several decades by a wide array of people with different priorities who, in many cases, did not know of each other's existence.
Features have thus arisen from many sources, and have not always been designed in especially consistent ways. Furthermore, because of the unique characteristics of the Web, implementation bugs have often become de-facto, and now de-jure, standards, as content is often unintentionally written in ways that rely on them before they can be fixed.
Despite all this, efforts have been made to adhere to certain design goals. These are described in the next few subsections.
This section is non-normative.
To avoid exposing Web authors to the complexities of multithreading, the HTML and DOM APIs are designed such that no script can ever detect the simultaneous execution of other scripts. Even with workers, the intent is that the behavior of implementations can be thought of as completely serialising the execution of all scripts in all browsing contexts.
The navigator.getStorageUpdates()
method, in this model, is equivalent to allowing other scripts to
run while the calling script is blocked.
This section is non-normative.
This specification interacts with and relies on a wide variety of other specifications. In certain circumstances, unfortunately, the desire to be compatible with legacy content has led to this specification violating the requirements of these other specifications. Whenever this has occurred, the transgressions have been noted as "willful violations".
This section is non-normative.
This specification describes a new revision of the HTML language and its associated DOM API.
The requirements in this specification for features that were already in HTML4 and DOM2 HTML are based primarily on the implementation and deployment experience collected over the past ten years. Some features have been removed from the language, based on best current practices; implementation requirements for some of these, as well as for non-standard features that have nonetheless garnered wide use, are still included in this specification to allow implementations to continue supporting legacy content. [HTML4] [DOM2HTML]
A separate document has been published by the W3C HTML working group to provide a more detailed reference of the differences between this specification and the language described in the HTML 4 specification. [HTMLDIFF]
This section is non-normative.
This specification is intended to replace XHTML 1.0 as the normative definition of the XML serialization of the HTML vocabulary. [XHTML10]
While this specification updates the semantics and requirements of the vocabulary defined by XHTML Modularization 1.1 and used by XHTML 1.1, it does not attempt to provide a replacement for the modularization scheme defined and used by those (and other) specifications, and therefore cannot be considered a complete replacement for them. [XHTMLMOD] [XHTML11]
Thus, authors and implementors who do not need such a modularization scheme can consider this specification a replacement for XHTML 1.x, but those who do need such a mechanism are encouraged to continue using the XHTML 1.1 line of specifications.
This section is non-normative.
This specification defines an abstract language for describing documents and applications, and some APIs for interacting with in-memory representations of resources that use this language.
The in-memory representation is known as "DOM5 HTML", or "the DOM" for short.
There are various concrete syntaxes that can be used to transmit resources that use this abstract language, two of which are defined in this specification.
The first such concrete syntax is "HTML5". This is the format
recommended for most authors. It is compatible with all legacy Web
browsers. If a document is transmitted with the MIME type text/html, then it will be processed as an "HTML5"
document by Web browsers.
The second concrete syntax uses XML, and is known as
"XHTML5". When a document is transmitted with an XML MIME
type, such as application/xhtml+xml,
then it is processed by an XML processor by Web browsers, and
treated as an "XHTML5" document. Authors are reminded that the
processing for XML and HTML differs; in particular, even minor
syntax errors will prevent an XML document from being rendered
fully, whereas they would be ignored in the "HTML5" syntax.
The "DOM5 HTML", "HTML5", and "XHTML5" representations cannot all
represent the same content. For example, namespaces cannot be
represented using "HTML5", but they are supported in "DOM5 HTML" and
"XHTML5". Similarly, documents that use the noscript
feature can be represented using "HTML5", but cannot be represented
with "XHTML5" and "DOM5 HTML". Comments that contain the string
"-->" can be represented in "DOM5 HTML" but
not in "HTML5" and "XHTML5". And so forth.
This section is non-normative.
This specification is divided into the following major sections:
There are also a couple of appendices, defining rendering rules for Web browsers and listing areas that are out of scope for this specification.
This specification should be read like all other specifications. First, it should be read cover-to-cover, multiple times. Then, it should be read backwards at least once. Then it should be read by picking random sections from the contents list and following all the cross-references.
This is a definition, requirement, or explanation.
This is a note.
This is an example.
This is an open issue.
This is a warning.
interface Example {
// this is an IDL definition
};
method( [ optionalArgument ] )This is a note to authors describing the usage of an interface.
/* this is a CSS fragment */
The defining instance of a term is marked up like this. Uses of that term are marked up like this or like this.
The defining instance of an element, attribute, or API is marked
up like this. References to
that element, attribute, or API are marked up like this.
Other code fragments are marked up like
this.
Variables are marked up like this.
This is an implementation requirement.
This section is non-normative.
A basic HTML document looks like this:
<!DOCTYPE HTML> <html> <head> <title>Sample page</title> </head> <body> <h1>Sample page</h1> <p>This is a <a href="demo.html">simple</a> sample.</p> </body> </html>
HTML documents consist of a tree of elements and text. Each
element is denoted by a start
tag, such as "<body>", and an end tag, such as "</body>". (Certain start tags and end tags can in
certain cases be omitted
and are implied by other tags.)
Tags have to be nested correctly, so that elements do not partially overlap each other:
<p>This is <em>very <strong>wrong</em>!</strong></p>
<p>This <em>is <strong>correct</strong>.</em></p>
This specification defines a set of elements that can be used in HTML, along with rules about the ways in which the elements can be nested.
Elements can have attributes, which control how the elements
work. In the example above, there is a hyperlink,
formed using the a element and its href attribute:
<a href="demo.html">simple</a>
Attributes are placed
inside the start tag, and consist of a name and a value, separated by an "=" character. The attribute value can be left
unquoted if it is a keyword, but generally will be quoted. (The
value can also be omitted altogether if it is empty.)
The tree formed by an HTML document in this way is turned into a DOM tree when parsed. This DOM tree can then be manipulated from scripts. Since DOM trees are the "live" representation of an HTML document, this specification is mostly phrased in terms of DOM trees, instead of the serialisation described above.
Each element in the DOM tree is represented by an object, and
thus objects have APIs so that they can be manipulated. For
instance, a link can have its "href" attributed changed in
several ways:
var a = document.links[0]; // obtain the first link in the document a.href = 'sample.html'; // change the destination URL of the link a.protocol = 'https'; // change just the scheme part of the URL
HTML documents represent a media-independent description of interactive content. HTML documents might be rendered to a screen, or through a speech synthesizer, or on a braille display. To influence exactly how such rendering takes place, authors can use a styling language such as CSS.
In the following example, the page has been made yellow-on-blue using CSS.
<!DOCTYPE HTML>
<html>
<head>
<title>Sample styled page</title>
<style>
body { background: navy; color: yellow; }
</style>
</head>
<body>
<h1>Sample styled page</h1>
<p>This page is just a demo.</p>
</body>
</html>
For more details on how to use HTML, authors are encouraged to consult tutorials and guides. Some of the examples included in this specification might also be of use, but the novice author is cautioned that this specification, by necessity, defines the language with a level of detail that may be difficult to understand at first.
This specification refers to both HTML and XML attributes and DOM attributes, often in the same context. When it is not clear which is being referred to, they are referred to as content attributes for HTML and XML attributes, and DOM attributes for those from the DOM. Similarly, the term "properties" is used for both JavaScript object properties and CSS properties. When these are ambiguous they are qualified as object properties and CSS properties respectively.
Generally, when the specification states that a feature applies to the HTML syntax or the XHTML syntax, it also includes the other. When a feature specifically only applies to one of the two languages, it is called out by explicitly stating that it does not apply to the other format, as in "for HTML, ... (this does not apply to XHTML)".
This specification uses the term document to refer to any use of HTML, ranging from short static documents to long essays or reports with rich multimedia, as well as to fully-fledged interactive applications.
For simplicity, terms such as shown, displayed, and visible might sometimes be used when referring to the way a document is rendered to the user. These terms are not meant to imply a visual medium; they must be considered to apply to other media in equivalent ways.
When an algorithm B says to return to another algorithm A, it implies that A called B. Upon returning to A, the implementation must continue from where it left off in calling B.
To ease migration from HTML to XHTML, UAs
conforming to this specification will place elements in HTML in the
http://www.w3.org/1999/xhtml namespace, at least for
the purposes of the DOM and CSS. The term "elements in the HTML
namespace", or "HTML elements" for short, when used
in this specification, thus refers to both HTML and XHTML
elements.
Unless otherwise stated, all elements defined or mentioned in
this specification are in the
http://www.w3.org/1999/xhtml namespace, and all
attributes defined or mentioned in this specification have no
namespace (they are in the per-element partition).
When an XML name, such as an attribute or element name, is
referred to in the form prefix:localName, as in xml:id or
svg:rect, it refers to a name with the local name localName and the namespace given by the prefix, as
defined by the following table:
xmlhttp://www.w3.org/XML/1998/namespacehtmlhttp://www.w3.org/1999/xhtmlsvghttp://www.w3.org/2000/svgAttribute names are said to be XML-compatible if they
match the Name production defined in XML, they contain no
U+003A COLON (:) characters, and their first three characters are
not an ASCII case-insensitive match for the string
"xml". [XML]
The term XML MIME type is used to refer to the MIME
types text/xml, application/xml, and any MIME type ending with the
four characters "+xml". [RFC3023]
The term root element, when not explicitly qualified as referring to the document's root element, means the furthest ancestor element node of whatever node is being discussed, or the node itself if it has no ancestors. When the node is a part of the document, then that is indeed the document's root element; however, if the node is not currently part of the document tree, the root element will be an orphaned node.
A node's home subtree is the subtree rooted at that node's root element.
The Document of a Node (such as an
element) is the Document that the Node's
ownerDocument DOM attribute returns.
When an element's root element is the root
element of a Document, it is said to be in
a Document. An element is said to have been inserted into a
document when its root element changes and is now
the document's root element. Analogously, an element is
said to have been removed from a document when its root
element changes from being the document's root
element to being another element.
If a Node is in a Document
then that Document is always the Node's
Document, and the Node's ownerDocument DOM attribute thus always returns that
Document.
The term tree order means a pre-order, depth-first
traversal of DOM nodes involved (through the parentNode/childNodes
relationship).
When it is stated that some element or attribute is ignored, or treated as some other value, or handled as if it was something else, this refers only to the processing of the node after it is in the DOM. A user agent must not mutate the DOM in such situations.
The term text node refers to any Text
node, including CDATASection nodes; specifically, any
Node with node type TEXT_NODE (3)
or CDATA_SECTION_NODE (4). [DOM3CORE]
A content attribute is said to change value only if its value new value is different than its previous value; setting an attribute to a value it already has does not change it.
The construction "a Foo object", where
Foo is actually an interface, is sometimes used instead
of the more accurate "an object implementing the interface
Foo".
A DOM attribute is said to be getting when its value is being retrieved (e.g. by author script), and is said to be setting when a new value is assigned to it.
If a DOM object is said to be live, then that means that any attributes returning that object must always return the same object (not a new object each time), and the attributes and methods on that object must operate on the actual underlying data, not a snapshot of the data.
The terms fire and dispatch are used interchangeably in the context of events, as in the DOM Events specifications. [DOM3EVENTS]
The term plugin is used to mean any content handler, typically a third-party content handler, for Web content types that are not supported by the user agent natively, or for content types that do not expose a DOM, that supports rendering the content as part of the user agent's interface.
One example of a plugin would be a PDF viewer that is instantiated in a browsing context when the user navigates to a PDF file. This would count as a plugin regardless of whether the party that implemented the PDF viewer component was the same as that which implemented the user agent itself. However, a PDF viewer application that launches separate from the user agent (as opposed to using the same interface) is not a plugin by this definition.
This specification does not define a mechanism for interacting with plugins, as it is expected to be user-agent- and platform-specific. Some UAs might opt to support a plugin mechanism such as the Netscape Plugin API; others might use remote content converters or have built-in support for certain types. [NPAPI]
Browsers should take extreme care when interacting with external content intended for plugins. When third-party software is run with the same privileges as the user agent itself, vulnerabilities in the third-party software become as dangerous as those in the user agent.
An ASCII-compatible character encoding is a single-byte or variable-length encoding in which the bytes 0x09, 0x0A, 0x0C, 0x0D, 0x20 - 0x22, 0x26, 0x27, 0x2C - 0x3F, 0x41 - 0x5A, and 0x61 - 0x7A, ignoring bytes that are the second and later bytes of multibyte sequences, all correspond to single-byte sequences that map to the same Unicode characters as those bytes in ANSI_X3.4-1968 (US-ASCII). [RFC1345]
This includes such encodings as Shift_JIS and variants of ISO-2022, even though it is possible in this encodings for bytes like 0x70 to be part of longer sequences that are unrelated to their interpretation as ASCII. It excludes such encodings as UTF-7, UTF-16, HZ-GB-2312, GSM03.38, and EBCDIC variants.
The specification uses the term supported when referring to whether a user agent has an implementation capable of decoding the semantics of an external resource. A format or type is said to be supported if the implementation can process an external resource of that format or type without critical aspects of the resource being ignored. Whether a specific resource is supported can depend on what features of the resource's format are in use.
For example, a PNG image would be considered to be in a supported format if its pixel data could be decoded and rendered, even if, unbeknownst to the implementation, the image actually also contained animation data.
A MPEG4 video file would not be considered to be in a supported format if the compression format used was not supported, even if the implementation could determine the dimensions of the movie from the file's metadata.
All diagrams, examples, and notes in this specification are non-normative, as are all sections explicitly marked non-normative. Everything else in this specification is normative.
The key words "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in the normative parts of this document are to be interpreted as described in RFC2119. For readability, these words do not appear in all uppercase letters in this specification. [RFC2119]
Requirements phrased in the imperative as part of algorithms (such as "strip any leading space characters" or "return false and abort these steps") are to be interpreted with the meaning of the key word ("must", "should", "may", etc) used in introducing the algorithm.
This specification describes the conformance criteria for user agents (relevant to implementors) and documents (relevant to authors and authoring tool implementors).
There is no implied relationship between document conformance requirements and implementation conformance requirements. User agents are not free to handle non-conformant documents as they please; the processing model described in this specification applies to implementations regardless of the conformity of the input documents.
User agents fall into several (overlapping) categories with different conformance requirements.
Web browsers that support the XHTML syntax must process elements and attributes from the HTML namespace found in XML documents as described in this specification, so that users can interact with them, unless the semantics of those elements have been overridden by other specifications.
A conforming XHTML processor would, upon
finding an XHTML script element in an XML document,
execute the script contained in that element. However, if the
element is found within a transformation expressed in XSLT
(assuming the user agent also supports XSLT), then the processor
would instead treat the script element as an opaque
element that forms part of the transform.
Web browsers that support the HTML syntax must
process documents labeled as text/html as described
in this specification, so that users can interact with them.
User agents that support scripting must also be conforming implementations of the IDL fragments in this specification, as described in the Web IDL specification. [WEBIDL]
User agents that process HTML and XHTML documents purely to render non-interactive versions of them must comply to the same conformance criteria as Web browsers, except that they are exempt from requirements regarding user interaction.
Typical examples of non-interactive presentation user agents are printers (static UAs) and overhead displays (dynamic UAs). It is expected that most static non-interactive presentation user agents will also opt to lack scripting support.
A non-interactive but dynamic presentation UA would still execute scripts, allowing forms to be dynamically submitted, and so forth. However, since the concept of "focus" is irrelevant when the user cannot interact with the document, the UA would not need to support any of the focus-related DOM APIs.
Implementations that do not support scripting (or which have their scripting features disabled entirely) are exempt from supporting the events and DOM interfaces mentioned in this specification. For the parts of this specification that are defined in terms of an events model or in terms of the DOM, such user agents must still act as if events and the DOM were supported.
Scripting can form an integral part of an application. Web browsers that do not support scripting, or that have scripting disabled, might be unable to fully convey the author's intent.
Conformance checkers must verify that a document conforms to
the applicable conformance criteria described in this
specification. Automated conformance checkers are exempt from
detecting errors that require interpretation of the author's
intent (for example, while a document is non-conforming if the
content of a blockquote element is not a quote,
conformance checkers running without the input of human judgement
do not have to check that blockquote elements only
contain quoted material).
Conformance checkers must check that the input document conforms when parsed without a browsing context (meaning that no scripts are run, and that the parser's scripting flag is disabled), and should also check that the input document conforms when parsed with a browsing context in which scripts execute, and that the scripts never cause non-conforming states to occur other than transiently during script execution itself. (This is only a "SHOULD" and not a "MUST" requirement because it has been proven to be impossible. [COMPUTABLE])
The term "HTML5 validator" can be used to refer to a conformance checker that itself conforms to the applicable requirements of this specification.
XML DTDs cannot express all the conformance requirements of this specification. Therefore, a validating XML processor and a DTD cannot constitute a conformance checker. Also, since neither of the two authoring formats defined in this specification are applications of SGML, a validating SGML system cannot constitute a conformance checker either.
To put it another way, there are three types of conformance criteria:
A conformance checker must check for the first two. A simple DTD-based validator only checks for the first class of errors and is therefore not a conforming conformance checker according to this specification.
Applications and tools that process HTML and XHTML documents for reasons other than to either render the documents or check them for conformance should act in accordance to the semantics of the documents that they process.
A tool that generates document outlines but increases the nesting level for each paragraph and does not increase the nesting level for each section would not be conforming.
Authoring tools and markup generators must generate conforming documents. Conformance criteria that apply to authors also apply to authoring tools, where appropriate.
Authoring tools are exempt from the strict requirements of using elements only for their specified purpose, but only to the extent that authoring tools are not yet able to determine author intent.
For example, it is not conforming to use an
address element for arbitrary contact information;
that element can only be used for marking up contact information
for the author of the document or section. However, since an
authoring tool is likely unable to determine the difference, an
authoring tool is exempt from that requirement.
In terms of conformance checking, an editor is therefore required to output documents that conform to the same extent that a conformance checker will verify.
When an authoring tool is used to edit a non-conforming document, it may preserve the conformance errors in sections of the document that were not edited during the editing session (i.e. an editing tool is allowed to round-trip erroneous content). However, an authoring tool must not claim that the output is conformant if errors have been so preserved.
Authoring tools are expected to come in two broad varieties: tools that work from structure or semantic data, and tools that work on a What-You-See-Is-What-You-Get media-specific editing basis (WYSIWYG).
The former is the preferred mechanism for tools that author HTML, since the structure in the source information can be used to make informed choices regarding which HTML elements and attributes are most appropriate.
However, WYSIWYG tools are legitimate. WYSIWYG tools should use
elements they know are appropriate, and should not use elements
that they do not know to be appropriate. This might in certain
extreme cases mean limiting the use of flow elements to just a few
elements, like div, b, i,
and span and making liberal use of the style attribute.
All authoring tools, whether WYSIWYG or not, should make a best effort attempt at enabling users to create well-structured, semantically rich, media-independent content.
Some conformance requirements are phrased as requirements on elements, attributes, methods or objects. Such requirements fall into two categories: those describing content model restrictions, and those describing implementation behavior. Those in the former category are requirements on documents and authoring tools. Those in the second category are requirements on user agents.
Conformance requirements phrased as algorithms or specific steps may be implemented in any manner, so long as the end result is equivalent. (In particular, the algorithms defined in this specification are intended to be easy to follow, and not intended to be performant.)
User agents may impose implementation-specific limits on otherwise unconstrained inputs, e.g. to prevent denial of service attacks, to guard against running out of memory, or to work around platform-specific limitations.
For compatibility with existing content and prior specifications, this specification describes two authoring formats: one based on XML (referred to as the XHTML syntax), and one using a custom format inspired by SGML (referred to as the HTML syntax). Implementations may support only one of these two formats, although supporting both is encouraged.
The language in this specification assumes that the user agent expands all entity references, and therefore does not include entity reference nodes in the DOM. If user agents do include entity reference nodes in the DOM, then user agents must handle them as if they were fully expanded when implementing this specification. For example, if a requirement talks about an element's child text nodes, then any text nodes that are children of an entity reference that is a child of that element would be used as well. Entity references to unknown entities must be treated as if they contained just an empty text node for the purposes of the algorithms defined in this specification.
This specification relies on several other underlying specifications.
Implementations that support the XHTML syntax must support some version of XML, as well as its corresponding namespaces specification, because that syntax uses an XML serialization with namespaces. [XML] [XMLNAMES]
The Document Object Model (DOM) is a representation — a model — of a document and its content. The DOM is not just an API; the conformance criteria of HTML implementations are defined, in this specification, in terms of operations on the DOM. [DOM3CORE]
Implementations must support some version of DOM Core and DOM Events, because this specification is defined in terms of the DOM, and some of the features are defined as extensions to the DOM Core interfaces. [DOM3CORE] [DOM3EVENTS]
The IDL fragments in this specification must be interpreted as required for conforming IDL fragments, as described in the Web IDL specification. [WEBIDL]
Unless otherwise specified, if a DOM attribute that is a
floating point number type (float) is
assigned an Infinity or Not-a-Number value, a
NOT_SUPPORTED_ERR exception must be raised.
Unless otherwise specified, if a method with an argument that
is a floating point number type (float) is
passed an Infinity or Not-a-Number value, a
NOT_SUPPORTED_ERR exception must be raised.
Some parts of the language described by this specification only support JavaScript as the underlying scripting language. [ECMA262]
The term "JavaScript" is used to refer to ECMA262,
rather than the official term ECMAScript, since the term
JavaScript is more widely known. Similarly, the MIME type used to
refer to JavaScript in this specification is text/javascript, since that is the most commonly
used type, despite it being an
officially obsoleted type according to RFC 4329. [RFC4329]
Implementations must support some version of the Media Queries language. [MQ]
This specification does not require support of any particular network transport protocols, style sheet language, scripting language, or any of the DOM and WebAPI specifications beyond those described above. However, the language described by this specification is biased towards CSS as the styling language, JavaScript as the scripting language, and HTTP as the network protocol, and several features assume that those languages and protocols are in use.
This specification might have certain additional requirements on character encodings, image formats, audio formats, and video formats in the respective sections.
Vendor-specific proprietary extensions to this specification are strongly discouraged. Documents must not use such extensions, as doing so reduces interoperability and fragments the user base, allowing only users of specific user agents to access the content in question.
If markup extensions are needed, they should be done using XML, with elements or attributes from custom namespaces. If DOM extensions are needed, the members should be prefixed by vendor-specific strings to prevent clashes with future versions of this specification. Extensions must be defined so that the use of extensions does not contradict nor cause the non-conformance of functionality defined in the specification.
For example, while strongly discouraged to do so, an
implementation "Foo Browser" could add a new DOM attribute "fooTypeTime" to a control's DOM interface that
returned the time it took the user to select the current value of a
control (say). On the other hand, defining a new control that
appears in a form's elements
array would be in violation of the above requirement, as it would
violate the definition of elements given in this
specification.
User agents must treat elements and attributes that they do not understand as semantically neutral; leaving them in the DOM (for DOM processors), and styling them according to CSS (for CSS processors), but not inferring any meaning from them.
This specification defines several comparison operators for strings.
Comparing two strings in a case-sensitive manner means comparing them exactly, code point for code point.
Comparing two strings in an ASCII case-insensitive manner means comparing them exactly, code point for code point, except that the characters in the range U+0041 .. U+005A (i.e. LATIN CAPITAL LETTER A to LATIN CAPITAL LETTER Z) and the corresponding characters in the range U+0061 .. U+007A (i.e. LATIN SMALL LETTER A to LATIN SMALL LETTER Z) are considered to also match.
Comparing two strings in a compatibility caseless manner means using the Unicode compatibility caseless match operation to compare the two strings. [UNICODECASE]
Converting a string to ASCII uppercase means replacing all characters in the range U+0061 .. U+007A (i.e. LATIN SMALL LETTER A to LATIN SMALL LETTER Z) with the corresponding characters in the range U+0041 .. U+005A (i.e. LATIN CAPITAL LETTER A to LATIN CAPITAL LETTER Z).
Converting a string to ASCII lowercase means replacing all characters in the range U+0041 .. U+005A (i.e. LATIN CAPITAL LETTER A to LATIN CAPITAL LETTER Z) with the corresponding characters in the range U+0061 .. U+007A (i.e. LATIN SMALL LETTER A to LATIN SMALL LETTER Z).
A string pattern is a prefix match for a string s when pattern is not longer than s and truncating s to pattern's length leaves the two strings as matches of each other.
There are various places in HTML that accept particular data types, such as dates or numbers. This section describes what the conformance criteria for content in those formats is, and how to parse them.
Implementors are strongly urged to carefully examine any third-party libraries they might consider using to implement the parsing of syntaxes described below. For example, date libraries are likely to implement error handling behavior that differs from what is required in this specification, since error-handling behavior is often not defined in specifications that describe date syntaxes similar to those used in this specification, and thus implementations tend to vary greatly in how they handle errors.
The space characters, for the purposes of this specification, are U+0020 SPACE, U+0009 CHARACTER TABULATION (tab), U+000A LINE FEED (LF), U+000C FORM FEED (FF), and U+000D CARRIAGE RETURN (CR).
The White_Space characters are those that have the Unicode property "White_Space". [UNICODE]
The alphanumeric ASCII characters are those in the ranges U+0030 DIGIT ZERO .. U+0039 DIGIT NINE, U+0041 LATIN CAPITAL LETTER A .. U+005A LATIN CAPITAL LETTER Z, U+0061 LATIN SMALL LETTER A .. U+007A LATIN SMALL LETTER Z.
Some of the micro-parsers described below follow the pattern of having an input variable that holds the string being parsed, and having a position variable pointing at the next character to parse in input.
For parsers based on this pattern, a step that requires the user agent to collect a sequence of characters means that the following algorithm must be run, with characters being the set of characters that can be collected:
Let input and position be the same variables as those of the same name in the algorithm that invoked these steps.
Let result be the empty string.
While position doesn't point past the end of input and the character at position is one of the characters, append that character to the end of result and advance position to the next character in input.
Return result.
The step skip whitespace means that the user agent must collect a sequence of characters that are space characters. The step skip White_Space characters means that the user agent must collect a sequence of characters that are White_Space characters. In both cases, the collected characters are not used. [UNICODE]
When a user agent is to strip line breaks from a string, the user agent must remove any U+000A LINE FEED (LF) and U+000D CARRIAGE RETURN (CR) characters from that string.
The code-point length of a string is the number of Unicode code points in that string.
A number of attributes are boolean attributes. The presence of a boolean attribute on an element represents the true value, and the absence of the attribute represents the false value.
If the attribute is present, its value must either be the empty string or a value that is an ASCII case-insensitive match for the attribute's canonical name, with no leading or trailing whitespace.
The values "true" and "false" are not allowed on boolean attributes. To represent a false value, the attribute has to be omitted altogether.
Some attributes are defined as taking one of a finite set of keywords. Such attributes are called enumerated attributes. The keywords are each defined to map to a particular state (several keywords might map to the same state, in which case some of the keywords are synonyms of each other; additionally, some of the keywords can be said to be non-conforming, and are only in the specification for historical reasons). In addition, two default states can be given. The first is the invalid value default, the second is the missing value default.
If an enumerated attribute is specified, the attribute's value must be an ASCII case-insensitive match for one of the given keywords that are not said to be non-conforming, with no leading or trailing whitespace.
When the attribute is specified, if its value is an ASCII case-insensitive match for one of the given keywords then that keyword's state is the state that the attribute represents. If the attribute value matches none of the given keywords, but the attribute has an invalid value default, then the attribute represents that state. Otherwise, if the attribute value matches none of the keywords but there is a missing value default state defined, then that is the state represented by the attribute. Otherwise, there is no default, and invalid values must be ignored.
When the attribute is not specified, if there is a missing value default state defined, then that is the state represented by the (missing) attribute. Otherwise, the absence of the attribute means that there is no state represented.
The empty string can be a valid keyword.
A string is a valid non-negative integer if it consists of one or more characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9).
A valid non-negative integer represents the number that is represented in base ten by that string of digits.
The rules for parsing non-negative integers are as given in the following algorithm. When invoked, the steps must be followed in the order given, aborting at the first step that returns a value. This algorithm will either return zero, a positive integer, or an error. Leading spaces are ignored. Trailing spaces and any trailing garbage characters are ignored.
Let input be the string being parsed.
Let position be a pointer into input, initially pointing at the start of the string.
Let value have the value 0.
Skip whitespace.
If position is past the end of input, return an error.
If the next character is a U+002B PLUS SIGN character (+), advance position to the next character.
If position is past the end of input, return an error.
If the next character is not one of U+0030 DIGIT ZERO (0) .. U+0039 DIGIT NINE (9), then return an error.
Loop: If the next character is one of U+0030 DIGIT ZERO (0) .. U+0039 DIGIT NINE (9):
Return value.
A string is a valid integer if it consists of one or more characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), optionally prefixed with a U+002D HYPHEN-MINUS ("-") character.
A valid integer without a U+002D HYPHEN-MINUS ("-") prefix represents the number that is represented in base ten by that string of digits. A valid integer with a U+002D HYPHEN-MINUS ("-") prefix represents the number represented in base ten by the string of digits that follows the U+002D HYPHEN-MINUS, subtracted from zero.
The rules for parsing integers are similar to the rules for non-negative integers, and are as given in the following algorithm. When invoked, the steps must be followed in the order given, aborting at the first step that returns a value. This algorithm will either return an integer or an error. Leading spaces are ignored. Trailing spaces and trailing garbage characters are ignored.
Let input be the string being parsed.
Let position be a pointer into input, initially pointing at the start of the string.
Let value have the value 0.
Let sign have the value "positive".
Skip whitespace.
If position is past the end of input, return an error.
If the character indicated by position (the first character) is a U+002D HYPHEN-MINUS ("-") character:
If the next character is not one of U+0030 DIGIT ZERO (0) .. U+0039 DIGIT NINE (9), then return an error.
If the next character is one of U+0030 DIGIT ZERO (0) .. U+0039 DIGIT NINE (9):
If sign is "positive", return value, otherwise return 0-value.
A string is a valid floating point number if it consists of:
A valid floating point number represents the number obtained by multiplying the significand by ten raised to the power of the exponent, where the significand is the first number, interpreted as base ten (including the decimal point and the number after the decimal point, if any, and interpreting the significand as a negative number if the whole string starts with a U+002D HYPHEN-MINUS ("-") character and the number is not zero), and where the exponent is the number after the E, if any (interpreted as a negative number if there is a U+002D HYPHEN-MINUS ("-") character between the E and the number and the number is not zero, or else ignoring a U+002B PLUS SIGN ("+") character between the E and the number if there is one). If there is no E, then the exponent is treated as zero.
The values ±Infinity and NaN are not valid floating point numbers.
The best representation of the floating point number n is the string obtained from applying the JavaScript operator ToString to n.
The rules for parsing floating point number values are as given in the following algorithm. As with the previous algorithms, when this one is invoked, the steps must be followed in the order given, aborting at the first step that returns something. This algorithm will either return a number or an error. Leading spaces are ignored. Trailing spaces and garbage characters are ignored.
Let input be the string being parsed.
Let position be a pointer into input, initially pointing at the start of the string.
Let value have the value 1.
Let divisor have the value 1.
Let exponent have the value 1.
Skip whitespace.
If position is past the end of input, return an error.
If the character indicated by position is a U+002D HYPHEN-MINUS ("-") character:
If the character indicated by position is not one of U+0030 DIGIT ZERO (0) .. U+0039 DIGIT NINE (9), then return an error.
Collect a sequence of characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), and interpret the resulting sequence as a base-ten integer. Multiply value by that integer.
If the character indicated by position is a U+002E FULL STOP ("."), run these substeps:
Advance position to the next character.
If position is past the end of input, or if the character indicated by position is not one of U+0030 DIGIT ZERO (0) .. U+0039 DIGIT NINE (9), then return value.
Fraction loop: Multiply divisor by ten.
Advance position to the next character.
If position is past the end of input, then return value.
If the character indicated by position is one of U+0030 DIGIT ZERO (0) .. U+0039 DIGIT NINE (9), return to the step labeled fraction loop in these substeps.
If the character indicated by position is a U+0065 LATIN SMALL LETTER E character or a U+0045 LATIN CAPITAL LETTER E character, run these substeps:
Advance position to the next character.
If position is past the end of input, then return value.
If the character indicated by position is a U+002D HYPHEN-MINUS ("-") character:
If position is past the end of input, then return value.
Otherwise, if the character indicated by position is a U+002B PLUS SIGN ("+") character:
If position is past the end of input, then return value.
If the character indicated by position is not one of U+0030 DIGIT ZERO (0) .. U+0039 DIGIT NINE (9), then return value.
Collect a sequence of characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), and interpret the resulting sequence as a base-ten integer. Multiply exponent by that integer.
Multiply value by ten raised to the exponentth power.
Return value.
The algorithms described in this section are used by
the progress and meter elements.
A valid denominator punctuation character is one of the characters from the table below. There is a value associated with each denominator punctuation character, as shown in the table below.
| Denominator Punctuation Character | Value | |
|---|---|---|
| U+0025 PERCENT SIGN | % | 100 |
| U+066A ARABIC PERCENT SIGN | ٪ | 100 |
| U+FE6A SMALL PERCENT SIGN | ﹪ | 100 |
| U+FF05 FULLWIDTH PERCENT SIGN | ％ | 100 |
| U+2030 PER MILLE SIGN | ‰ | 1000 |
| U+2031 PER TEN THOUSAND SIGN | ‱ | 10000 |
The steps for finding one or two numbers of a ratio in a string are as follows:
The algorithm to find a number is as follows. It is given a string and a starting position, and returns either nothing, a number, or an error condition.
The rules for parsing dimension values are as given in the following algorithm. When invoked, the steps must be followed in the order given, aborting at the first step that returns a value. This algorithm will either return a number greater than or equal to 1.0, or an error; if a number is returned, then it is further categorized as either a percentage or a length.
Let input be the string being parsed.
Let position be a pointer into input, initially pointing at the start of the string.
Skip whitespace.
If position is past the end of input, return an error.
If the next character is a U+002B PLUS SIGN character (+), advance position to the next character.
Collect a sequence of characters that are U+0030 DIGIT ZERO (0) characters, and discard them.
If position is past the end of input, return an error.
If the next character is not one of U+0031 DIGIT ONE (1) .. U+0039 DIGIT NINE (9), then return an error.
Collect a sequence of characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), and interpret the resulting sequence as a base-ten integer. Let value be that number.
If position is past the end of input, return value as an integer.
If the next character is a U+002E FULL STOP character (.):
Advance position to the next character.
If the next character is not one of U+0030 DIGIT ZERO (0) .. U+0039 DIGIT NINE (9), then return value as an integer.
Collect a sequence of characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9). Let length be the number of characters collected. Let fraction be the result of interpreting the collected characters as a base-ten integer, and then dividing that number by 10length.
Increment value by fraction.
If position is past the end of input, return value as a length.
If the next character is a U+0025 PERCENT SIGN character (%), return value as a percentage.
Return value as a length.
A valid list of integers is a number of valid integers separated by U+002C COMMA characters, with no other characters (e.g. no space characters). In addition, there might be restrictions on the number of integers that can be given, or on the range of values allowed.
The rules for parsing a list of integers are as follows:
Let input be the string being parsed.
Let position be a pointer into input, initially pointing at the start of the string.
Let numbers be an initially empty list of integers. This list will be the result of this algorithm.
If there is a character in the string input at position position, and it is either a U+0020 SPACE, U+002C COMMA, or U+003B SEMICOLON character, then advance position to the next character in input, or to beyond the end of the string if there are no more characters.
If position points to beyond the end of input, return numbers and abort.
If the character in the string input at position position is a U+0020 SPACE, U+002C COMMA, or U+003B SEMICOLON character, then return to step 4.
Let negated be false.
Let value be 0.
Let started be false. This variable is set to true when the parser sees a number or a U+002D HYPHEN-MINUS ("-") character.
Let got number be false. This variable is set to true when the parser sees a number.
Let finished be false. This variable is set to true to switch parser into a mode where it ignores characters until the next separator.
Let bogus be false.
Parser: If the character in the string input at position position is:
Follow these substeps:
Follow these substeps:
Follow these substeps:
1,2,x,4".Follow these substeps:
Follow these substeps:
Advance position to the next character in input, or to beyond the end of the string if there are no more characters.
If position points to a character (and not to beyond the end of input), jump to the big Parser step above.
If negated is true, then negate value.
If got number is true, then append value to the numbers list.
Return the numbers list and abort.
The rules for parsing a list of dimensions are as follows. These rules return a list of zero or more pairs consisting of a number and a unit, the unit being one of percentage, relative, and absolute.
Let raw input be the string being parsed.
If the last character in raw input is a U+002C COMMA character (","), then remove that character from raw input.
Split the string raw input on commas. Let raw tokens be the resulting list of tokens.
Let result be an empty list of number/unit pairs.
For each token in raw tokens, run the following substeps:
Let input be the token.
Let position be a pointer into input, initially pointing at the start of the string.
Let value be the number 0.
Let unit be absolute.
If position is past the end of input, set unit to relative and jump to the last substep.
If the character at position is a character in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), collect a sequence of characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), interpret the resulting sequence as an integer in base ten, and increment value by that integer.
If the character at position is a U+002E FULL STOP character (.), run these substeps:
Collect a sequence of characters consisting of space characters and characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9). Let s be the resulting sequence.
Remove all space characters in s.
If s is not the empty string, run these subsubsteps:
Let length be the number of characters in s (after the spaces were removed).
Let fraction be the result of interpreting s as a base-ten integer, and then dividing that number by 10length.
Increment value by fraction.
Skip whitespace.
If the character at position is a U+0025 PERCENT SIGN (%) character, then set unit to percentage.
Otherwise, if the character at position is a U+002A ASTERISK character (*), then set unit to relative.
Add an entry to result consisting of the number given by value and the unit given by unit.
Return the list result.
In the algorithms below, the number of days in month month of year year is: 31 if month is 1, 3, 5, 7, 8, 10, or 12; 30 if month is 4, 6, 9, or 11; 29 if month is 2 and year is a number divisible by 400, or if year is a number divisible by 4 but not by 100; and 28 otherwise. This takes into account leap years in the Gregorian calendar. [GREGORIAN]
The digits in the date and time syntaxes defined in this section must be characters in the range U+0030 DIGIT ZERO to U+0039 DIGIT NINE, used to express numbers in base ten.
A month consists of a specific proleptic Gregorian date with no time-zone information and no date information beyond a year and a month. [GREGORIAN]
A string is a valid month string representing a year year and month month if it consists of the following components in the given order:
The rules to parse a month string are as follows. This will either return a year and month, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.
Let input be the string being parsed.
Let position be a pointer into input, initially pointing at the start of the string.
Parse a month component to obtain year and month. If this returns nothing, then fail.
If position is not beyond the end of input, then fail.
Return year and month.
The rules to parse a month component, given an input string and a position, are as follows. This will either return a year and a month, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.
Collect a sequence of characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9). If the collected sequence is not at least four characters long, then fail. Otherwise, interpret the resulting sequence as a base-ten integer. Let that number be the year.
If year is not a number greater than zero, then fail.
If position is beyond the end of input or if the character at position is not a U+002D HYPHEN-MINUS character, then fail. Otherwise, move position forwards one character.
Collect a sequence of characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9). If the collected sequence is not exactly two characters long, then fail. Otherwise, interpret the resulting sequence as a base-ten integer. Let that number be the month.
If month is not a number in the range 1 ≤ month ≤ 12, then fail.
Return year and month.
A date consists of a specific proleptic Gregorian date with no time-zone information, consisting of a year, a month, and a day. [GREGORIAN]
A string is a valid date string representing a year year, month month, and day day if it consists of the following components in the given order:
The rules to parse a date string are as follows. This will either return a date, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.
Let input be the string being parsed.
Let position be a pointer into input, initially pointing at the start of the string.
Parse a date component to obtain year, month, and day. If this returns nothing, then fail.
If position is not beyond the end of input, then fail.
Let date be the date with year year, month month, and day day.
Return date.
The rules to parse a date component, given an input string and a position, are as follows. This will either return a year, a month, and a day, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.
Parse a month component to obtain year and month. If this returns nothing, then fail.
Let maxday be the number of days in month month of year year.
If position is beyond the end of input or if the character at position is not a U+002D HYPHEN-MINUS character, then fail. Otherwise, move position forwards one character.
Collect a sequence of characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9). If the collected sequence is not exactly two characters long, then fail. Otherwise, interpret the resulting sequence as a base-ten integer. Let that number be the day.
If day is not a number in the range 1 ≤ month ≤ maxday, then fail.
Return year, month, and day.
A time consists of a specific time with no time-zone information, consisting of an hour, a minute, a second, and a fraction of a second.
A string is a valid time string representing an hour hour, a minute minute, and a second second if it consists of the following components in the given order:
The second component cannot be 60 or 61; leap seconds cannot be represented.
The rules to parse a time string are as follows. This will either return a time, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.
Let input be the string being parsed.
Let position be a pointer into input, initially pointing at the start of the string.
Parse a time component to obtain hour, minute, and second. If this returns nothing, then fail.
If position is not beyond the end of input, then fail.
Let time be the time with hour hour, minute minute, and second second.
Return time.
The rules to parse a time component, given an input string and a position, are as follows. This will either return an hour, a minute, and a second, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.
Collect a sequence of characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9). If the collected sequence is not exactly two characters long, then fail. Otherwise, interpret the resulting sequence as a base-ten integer. Let that number be the hour.
If position is beyond the end of input or if the character at position is not a U+003A COLON character, then fail. Otherwise, move position forwards one character.
Collect a sequence of characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9). If the collected sequence is not exactly two characters long, then fail. Otherwise, interpret the resulting sequence as a base-ten integer. Let that number be the minute.
Let second be a string with the value "0".
If position is not beyond the end of input and the character at position is a U+003A COLON, then run these substeps:
Advance position to the next character in input.
If position is beyond the end of input, or at the last character in input, or if the next two characters in input starting at position are not two characters both in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), then fail.
Collect a sequence of characters that are either characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9) or U+002E FULL STOP characters. If the collected sequence has more than one U+002E FULL STOP characters, or if the last character in the sequence is a U+002E FULL STOP character, then fail. Otherwise, let the collected string be second instead of its previous value.
Interpret second as a base-ten number (possibly with a fractional part). Let second be that number instead of the string version.
If second is not a number in the range 0 ≤ second < 60, then fail.
Return hour, minute, and second.
A local date and time consists of a specific proleptic Gregorian date, consisting of a year, a month, and a day, and a time, consisting of an hour, a minute, a second, and a fraction of a second, but expressed without a time zone. [GREGORIAN]
A string is a valid local date and time string representing a date and time if it consists of the following components in the given order:
The rules to parse a local date and time string are as follows. This will either return a date and time, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.
Let input be the string being parsed.
Let position be a pointer into input, initially pointing at the start of the string.
Parse a date component to obtain year, month, and day. If this returns nothing, then fail.
If position is beyond the end of input or if the character at position is not a U+0054 LATIN CAPITAL LETTER T character then fail. Otherwise, move position forwards one character.
Parse a time component to obtain hour, minute, and second. If this returns nothing, then fail.
If position is not beyond the end of input, then fail.
Let date be the date with year year, month month, and day day.
Let time be the time with hour hour, minute minute, and second second.
Return date and time.
A global date and time consists of a specific proleptic Gregorian date, consisting of a year, a month, and a day, and a time, consisting of an hour, a minute, a second, and a fraction of a second, expressed with a time zone, consisting of a number of hours and minutes. [GREGORIAN]
A string is a valid global date and time string representing a date, time, and a time-zone offset if it consists of the following components in the given order:
This format allows for time zone offsets from -23:59 to +23:59. In practice, however, the range of actual time zones is -12:00 to +14:00, and the minutes component of actual time zones is always either 00, 30, or 45.
The following are some examples of dates written as valid global date and time strings.
0037-12-13T00:00Z"1979-10-14T12:00:00.001-04:00"8592-01-01T02:09+02:09"Several things are notable about these dates:
The rules to parse a global date and time string are as follows. This will either return a time in UTC, with associated time-zone information for round tripping or display purposes, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.
Let input be the string being parsed.
Let position be a pointer into input, initially pointing at the start of the string.
Parse a date component to obtain year, month, and day. If this returns nothing, then fail.
If position is beyond the end of input or if the character at position is not a U+0054 LATIN CAPITAL LETTER T character then fail. Otherwise, move position forwards one character.
Parse a time component to obtain hour, minute, and second. If this returns nothing, then fail.
If position is beyond the end of input, then fail.
Parse a time-zone component to obtain timezonehours and timezoneminutes. If this returns nothing, then fail.
If position is not beyond the end of input, then fail.
Let time be the moment in time at year year, month month, day day, hours hour, minute minute, second second, subtracting timezonehours hours and timezoneminutes minutes. That moment in time is a moment in the UTC time zone.
Let timezone be timezonehours hours and timezoneminutes minutes from UTC.
Return time and timezone.
The rules to parse a time-zone component, given an input string and a position, are as follows. This will either return time-zone hours and time-zone minutes, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.
If the character at position is a U+005A LATIN CAPITAL LETTER Z, then:
Let timezonehours be 0.
Let timezoneminutes be 0.
Advance position to the next character in input.
Otherwise, if the character at position is either a U+002B PLUS SIGN ("+") or a U+002D HYPHEN-MINUS ("-"), then:
If the character at position is a U+002B PLUS SIGN ("+"), let sign be "positive". Otherwise, it's a U+002D HYPHEN-MINUS ("-"); let sign be "negative".
Advance position to the next character in input.
Collect a sequence of characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9). If the collected sequence is not exactly two characters long, then fail. Otherwise, interpret the resulting sequence as a base-ten integer. Let that number be the timezonehours.
If position is beyond the end of input or if the character at position is not a U+003A COLON character, then fail. Otherwise, move position forwards one character.
Collect a sequence of characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9). If the collected sequence is not exactly two characters long, then fail. Otherwise, interpret the resulting sequence as a base-ten integer. Let that number be the timezoneminutes.
Return timezonehours and timezoneminutes.
A week consists of a week-year number and a week number representing a seven day period. Each week-year in this calendaring system has either 52 weeks or 53 weeks, as defined below. A week is a seven-day period. The week starting on the Gregorian date Monday December 29th 1969 (1969-12-29) is defined as week number 1 in week-year 1970. Consecutive weeks are numbered sequentially. The week before the number 1 week in a week-year is the last week in the previous week-year, and vice versa. [GREGORIAN]
A week-year with a number year has 53 weeks if it corresponds to either a year year in the proleptic Gregorian calendar that has a Thursday as its first day (January 1st), or a year year in the proleptic Gregorian calendar that has a Wednesday as its first day (January 1st) and where year is a number divisible by 400, or a number divisible by 4 but not by 100. All other week-years have 52 weeks.
The week number of the last day of a week-year with 53 weeks is 53; the week number of the last day of a week-year with 52 weeks is 52.
The week-year number of a particular day can be different than the number of the year that contains that day in the proleptic Gregorian calendar. The first week in a week-year y is the week that contains the first Thursday of the Gregorian year y.
A string is a valid week string representing a week-year year and week week if it consists of the following components in the given order:
The rules to parse a week string are as follows. This will either return a week-year number and week number, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.
Let input be the string being parsed.
Let position be a pointer into input, initially pointing at the start of the string.
Collect a sequence of characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9). If the collected sequence is not at least four characters long, then fail. Otherwise, interpret the resulting sequence as a base-ten integer. Let that number be the year.
If year is not a number greater than zero, then fail.
If position is beyond the end of input or if the character at position is not a U+002D HYPHEN-MINUS character, then fail. Otherwise, move position forwards one character.
If position is beyond the end of input or if the character at position is not a U+0057 LATIN CAPITAL LETTER W character, then fail. Otherwise, move position forwards one character.
Collect a sequence of characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9). If the collected sequence is not exactly two characters long, then fail. Otherwise, interpret the resulting sequence as a base-ten integer. Let that number be the week.
Let maxweek be the week number of the last day of year year.
If week is not a number in the range 1 ≤ week ≤ maxweek, then fail.
If position is not beyond the end of input, then fail.
Return the week-year number year and the week number week.
A date or time string consists of either a date, a time, or a global date and time.
A string is a valid date or time string if it is also one of the following:
A string is a valid date or time string in content if it consists of zero or more White_Space characters, followed by a valid date or time string, followed by zero or more further White_Space characters.
The rules to parse a date or time string are as follows. The algorithm is invoked with a flag indicating if the in attribute variant or the in content variant is to be used. The algorithm will either return a date, a time, a global date and time, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.
Let input be the string being parsed.
Let position be a pointer into input, initially pointing at the start of the string.
For the in content variant: skip White_Space characters.
Set start position to the same position as position.
Set the date present and time present flags to true.
Parse a date component to obtain year, month, and day. If this fails, then set the date present flag to false.
If date present is true, and position is not beyond the end of input, and the character at position is a U+0054 LATIN CAPITAL LETTER T character, then advance position to the next character in input.
Otherwise, if date present is true, and either position is beyond the end of input or the character at position is not a U+0054 LATIN CAPITAL LETTER T character, then set time present to false.
Otherwise, if date present is false, set position back to the same position as start position.
If the time present flag is true, then parse a time component to obtain hour, minute, and second. If this returns nothing, then set the time present flag to false.
If both the date present and time present flags are false, then fail.
If the time present flag is true, but position is beyond the end of input, then fail.
If the date present and time present flags are both true, parse a time-zone component to obtain timezonehours and timezoneminutes. If this returns nothing, then fail.
For the in content variant: skip White_Space characters.
If position is not beyond the end of input, then fail.
If the date present flag is true and the time present flag is false, then let date be the date with year year, month month, and day day, and return date.
Otherwise, if the time present flag is true and the date present flag is false, then let time be the time with hour hour, minute minute, and second second, and return time.
Otherwise, let time be the moment in time at year year, month month, day day, hours hour, minute minute, second second, subtracting timezonehours hours and timezoneminutes minutes, that moment in time being a moment in the UTC time zone; let timezone be timezonehours hours and timezoneminutes minutes from UTC; and return time and timezone.
A simple color consists of three 8-bit numbers in the range 0..255, representing the red, green, and blue components of the color respectively, in the sRGB color space. [SRGB]
A string is a valid simple color if it is exactly seven characters long, and the first character is a U+0023 NUMBER SIGN (#) character, and the remaining six characters are all in the range U+0030 DIGIT ZERO (0) .. U+0039 DIGIT NINE (9), U+0041 LATIN CAPITAL LETTER A .. U+0046 LATIN CAPITAL LETTER F, U+0061 LATIN SMALL LETTER A .. U+0066 LATIN SMALL LETTER F, with the first two digits representing the red component, the middle two digits representing the green component, and the last two digits representing the blue component, in hexadecimal.
A string is a valid lowercase simple color if it is a valid simple color and doesn't use any characters in the range U+0041 LATIN CAPITAL LETTER A .. U+0046 LATIN CAPITAL LETTER F.
The rules for parsing simple color values are as given in the following algorithm. When invoked, the steps must be followed in the order given, aborting at the first step that returns a value. This algorithm will either return a simple color or an error.
Let input be the string being parsed.
If input is not exactly seven characters long, then return an error.
If the first character in input is not a U+0023 NUMBER SIGN (#) character, then return an error.
If the last six characters of input are not all in the range U+0030 DIGIT ZERO (0) .. U+0039 DIGIT NINE (9), U+0041 LATIN CAPITAL LETTER A .. U+0046 LATIN CAPITAL LETTER F, U+0061 LATIN SMALL LETTER A .. U+0066 LATIN SMALL LETTER F, then return an error.
Let result be a simple color.
Interpret the second and third characters as a hexadecimal number and let the result be the red component of result.
Interpret the fourth and fifth characters as a hexadecimal number and let the result be the green component of result.
Interpret the sixth and seventh characters as a hexadecimal number and let the result be the blue component of result.
Return result.
The rules for serializing simple color values given a simple color are as given in the following algorithm:
Let result be a string consisting of a single U+0023 NUMBER SIGN (#) character.
Convert the red, green, and blue components in turn to two-digit hexadecimal numbers using the digits U+0030 DIGIT ZERO (0) .. U+0039 DIGIT NINE (9) and U+0061 LATIN SMALL LETTER A .. U+0066 LATIN SMALL LETTER F, zero-padding if necessary, and append these numbers to result, in the order red, green, blue.
Return result, which will be a valid lowercase simple color.
Some obsolete legacy attributes parse colors in a more complicated manner, using the rules for parsing a legacy color value, which are given in the following algorithm. When invoked, the steps must be followed in the order given, aborting at the first step that returns a value. This algorithm will either return a simple color or an error.
Let input be the string being parsed.
If input is the empty string, then return an error.
If input is an ASCII
case-insensitive match for the string "transparent", then return an error.
If input is an ASCII case-insensitive match for one of the keywords listed in the SVG color keywords or CSS2 System Colors sections of the CSS3 Color specification, then return the simple color corresponding to that keyword. [CSSCOLOR]
If input is four characters long, and the first character in input is a U+0023 NUMBER SIGN (#) character, and the last three characters of input are all in the range U+0030 DIGIT ZERO (0) .. U+0039 DIGIT NINE (9), U+0041 LATIN CAPITAL LETTER A .. U+0046 LATIN CAPITAL LETTER F, and U+0061 LATIN SMALL LETTER A .. U+0066 LATIN SMALL LETTER F, then run these substeps:
Let result be a simple color.
Interpret the second character of input as a hexadecimal digit; let the red component of result be the resulting number multiplied by 17.
Interpret the third character of input as a hexadecimal digit; let the green component of result be the resulting number multiplied by 17.
Interpret the fourth character of input as a hexadecimal digit; let the blue component of result be the resulting number multiplied by 17.
Return result.
Replace any characters in input that
have a Unicode code point greater than U+FFFF (i.e. any characters
that are not in the basic multilingual plane) with the
two-character string "00".
If input is longer than 128 characters, truncate input, leaving only the first 128 characters.
If the first character in input is a U+0023 NUMBER SIGN character (#), remove it.
Replace any character in input that is not in the range U+0030 DIGIT ZERO (0) .. U+0039 DIGIT NINE (9), U+0041 LATIN CAPITAL LETTER A .. U+0046 LATIN CAPITAL LETTER F, and U+0061 LATIN SMALL LETTER A .. U+0066 LATIN SMALL LETTER F with the character U+0030 DIGIT ZERO (0).
While input's length is zero or not a multiple of three, append a U+0030 DIGIT ZERO (0) character to input.
Split input into three strings of equal length, to obtain three components. Let length be the length of those components (one third the length of input).
If length is greater than 8, then remove the leading length-8 characters in each component, and let length be 8.
While length is greater than two and the first character in each component is a U+0030 DIGIT ZERO (0) character, remove that character and reduce length by one.
If length is still greater than two, truncate each component, leaving only the first two characters in each.
Let result be a simple color.
Interpret the first component as a hexadecimal number; let the red component of result be the resulting number.
Interpret the second component as a hexadecimal number; let the green component of result be the resulting number.
Interpret the third component as a hexadecimal number; let the blue component of result be the resulting number.
Return result.
The 2D graphics context has a separate color syntax that also handles opacity.
A set of space-separated tokens is a set of zero or more words separated by one or more space characters, where words consist of any string of one or more characters, none of which are space characters.
A string containing a set of space-separated tokens may have leading or trailing space characters.
An unordered set of unique space-separated tokens is a set of space-separated tokens where none of the words are duplicated.
An ordered set of unique space-separated tokens is a set of space-separated tokens where none of the words are duplicated but where the order of the tokens is meaningful.
Sets of space-separated tokens sometimes have a defined set of allowed values. When a set of allowed values is defined, the tokens must all be from that list of allowed values; other values are non-conforming. If no such set of allowed values is provided, then all values are conforming.
When a user agent has to split a string on spaces, it must use the following algorithm:
Let input be the string being parsed.
Let position be a pointer into input, initially pointing at the start of the string.
Let tokens be a list of tokens, initially empty.
Skip whitespace
While position is not past the end of input:
Collect a sequence of characters that are not space characters.
Add the string collected in the previous step to tokens.
Skip whitespace
Return tokens.
When a user agent has to remove a token from a string, it must use the following algorithm:
Let input be the string being modified.
Let token be the token being removed. It will not contain any space characters.
Let output be the output string, initially empty.
Let position be a pointer into input, initially pointing at the start of the string.
If position is beyond the end of input, set the string being modified to output, and abort these steps.
If the character at position is a space character:
Append the character at position to the end of output.
Increment position so it points at the next character in input.
Return to step 5 in the overall set of steps.
Otherwise, the character at position is the first character of a token. Collect a sequence of characters that are not space characters, and let that be s.
If s is exactly equal to token, then:
Skip whitespace (in input).
Remove any space characters currently at the end of output.
If position is not past the end of input, and output is not the empty string, append a single U+0020 SPACE character at the end of output.
Otherwise, append s to the end of output.
Return to step 6 in the overall set of steps.
This causes any occurrences of the token to be removed from the string, and any spaces that were surrounding the token to be collapsed to a single space, except at the start and end of the string, where such spaces are removed.
A set of comma-separated tokens is a set of zero or
more tokens each separated from the next by a single U+002C COMMA
character (,), where tokens consist of any
string of zero or more characters, neither beginning nor ending with
space characters, nor
containing any U+002C COMMA characters (,),
and optionally surrounded by space
characters.
For instance, the string " a ,b,,d d " consists of four
tokens: "a", "b", the empty string, and "d d". Leading and
trailing whitespace around each token doesn't count as part of the
token, and the empty string can be a token.
Sets of comma-separated tokens sometimes have further restrictions on what consists a valid token. When such restrictions are defined, the tokens must all fit within those restrictions; other values are non-conforming. If no such restrictions are specified, then all values are conforming.
When a user agent has to split a string on commas, it must use the following algorithm:
Let input be the string being parsed.
Let position be a pointer into input, initially pointing at the start of the string.
Let tokens be a list of tokens, initially empty.
Token: If position is past the end of input, jump to the last step.
Collect a sequence of characters that are not
U+002C COMMA characters (,). Let s be the resulting sequence (which might be the
empty string).
Remove any leading or trailing sequence of space characters from s.
Add s to tokens.
If position is not past the end of input, then the character at position is a U+002C COMMA character (,); advance position past that
character.
Jump back to the step labeled token.
Return tokens.
A valid reversed DNS identifier is a string that consists of a series of IDNA labels in reverse order (i.e. starting with the top-level domain), the prefix of which, when reversed and converted to ASCII, corresponds to a registered domain.
For instance, the string "com.example.xn--74h" is a valid reversed DNS
identifier because the string "example.com" is a registered domain.
To check if a string is a valid reversed DNS identifier, conformance checkers must run the following algorithm:
Apply the IDNA ToASCII algorithm to the string, with both the AllowUnassigned and UseSTD3ASCIIRules flags set, but between steps 2 and 3 of the general ToASCII/ToUnicode algorithm (i.e. after splitting the domain name into individual labels), reverse the order of the labels.
If ToASCII fails to convert one of the components of the string, e.g. because it is too long or because it contains invalid characters, then the string is not valid; abort these steps. [RFC3490]
Check that the end of the resulting string matches a suffix in the Public Suffix List, and that there is at least one domain label before the matching substring. If it does not, or if there is not, then the string is not valid; abort these steps. [PSL]
Check that the domain name up to the label before the prefix that was matched in the previous string is a registered domain name.
A valid hash-name reference to an element of type type is a string consisting of a U+0023 NUMBER SIGN
(#) character followed by a string which
exactly matches the value of the name
attribute of an element in the document with type type.
The rules for parsing a hash-name reference to an element of type type are as follows:
If the string being parsed does not contain a U+0023 NUMBER SIGN character, or if the first such character in the string is the last character in the string, then return null and abort these steps.
Let s be the string from the character immediately after the first U+0023 NUMBER SIGN character in the string being parsed up to the end of that string.
Return the first element of type type
that has an id attribute whose value
is a case-sensitive match for s or
a name attribute whose value is a
compatibility caseless match for s.
A URL is a string used to identify a resource.
A URL is a valid URL if it is a valid Web address as defined by the Web addresses specification. [WEBADDRESSES]
A URL is an absolute URL if it is an absolute Web address as defined by the Web addresses specification. [WEBADDRESSES]
To parse a URL url into its component parts, the user agent must use the parse a Web address algorithm defined by the Web addresses specification. [WEBADDRESSES]
Parsing a URL results in the following components, again as defined by the Web addresses specification:
To resolve a URL to an absolute URL relative to either another absolute URL or an element, the user agent must use the resolve a Web address algorithm defined by the Web addresses specification. [WEBADDRESSES]
The document base URL of a Document
object is the document base Web address as defined by
the Web addresses specification. [WEBADDRESSES]
The term "URL" in this specification is used in a manner distinct from the precise technical meaning it is given in RFC 3986. Readers familiar with that RFC will find it easier to read this specification if they pretend the term "URL" as used herein is really called something else altogether. This is a willful violation of RFC 3986. [RFC3986]
When an xml:base attribute
changes, the attribute's element, and all descendant elements, are
affected by a base URL change.
When a document's document base URL changes, all elements in that document are affected by a base URL change.
When an element is moved from one document to another, if the two documents have different base URLs, then that element and all its descendants are affected by a base URL change.
When an element is affected by a base URL change, it must act as described in the following list:
If the absolute URL identified by the hyperlink is
being shown to the user, or if any data derived from that URL is
affecting the display, then the href attribute should be re-resolved relative to the element
and the UI updated appropriately.
For example, the CSS :link/:visited pseudo-classes might have
been affected.
If the hyperlink has a ping attribute and its absolute URL(s) are being shown to the
user, then the ping
attribute's tokens should be re-resolved relative to the element and the UI updated
appropriately.
q, blockquote,
section, article, ins, or
del element with a cite
attributeIf the absolute URL identified by the cite attribute is being shown to the user, or if
any data derived from that URL is affecting the display, then the
URL should be re-resolved relative to the element and the UI updated
appropriately.
The element is not directly affected.
Changing the base URL doesn't affect the image
displayed by img elements, although subsequent
accesses of the src DOM attribute
from script will return a new absolute URL that might
no longer correspond to the image being shown.
An interface that has a complement of URL decomposition attributes will have seven attributes with the following definitions:
attribute DOMString protocol;
attribute DOMString host;
attribute DOMString hostname;
attribute DOMString port;
attribute DOMString pathname;
attribute DOMString search;
attribute DOMString hash;
protocol [ = value ]Returns the current scheme of the underlying URL.
Can be set, to change the underlying URL's scheme.
host [ = value ]Returns the current host and port (if it's not the default port) in the underlying URL.
Can be set, to change the underlying URL's host and port.
The host and the port are separated by a colon. The port part, if omitted, will be assumed to be the current scheme's default port.
hostname [ = value ]Returns the current host in the underlying URL.
Can be set, to change the underlying URL's host.
port [ = value ]Returns the current port in the underlying URL.
Can be set, to change the underlying URL's port.
pathname [ = value ]Returns the current path in the underlying URL.
Can be set, to change the underlying URL's path.
search [ = value ]Returns the current query component in the underlying URL.
Can be set, to change the underlying URL's query component.
hash [ = value ]Returns the current fragment identifier in the underlying URL.
Can be set, to change the underlying URL's fragment identifier.
The attributes defined to be URL decomposition attributes must act as described for the attributes with the same corresponding names in this section.
In addition, an interface with a complement of URL decomposition attributes will define an input, which is a URL that the attributes act on, and a common setter action, which is a set of steps invoked when any of the attributes' setters are invoked.
The seven URL decomposition attributes have similar requirements.
On getting, if the input is an absolute URL that fulfills the condition given in the "getter condition" column corresponding to the attribute in the table below, the user agent must return the part of the input URL given in the "component" column, with any prefixes specified in the "prefix" column appropriately added to the start of the string and any suffixes specified in the "suffix" column appropriately added to the end of the string. Otherwise, the attribute must return the empty string.
On setting, the new value must first be mutated as described by the "setter preprocessor" column, then mutated by %-escaping any characters in the new value that are not valid in the relevant component as given by the "component" column. Then, if the input is an absolute URL and the resulting new value fulfills the condition given in the "setter condition" column, the user agent must make a new string output by replacing the component of the URL given by the "component" column in the input URL with the new value; otherwise, the user agent must let output be equal to the input. Finally, the user agent must invoke the common setter action with the value of output.
When replacing a component in the URL, if the component is part of an optional group in the URL syntax consisting of a character followed by the component, the component (including its prefix character) must be included even if the new value is the empty string.
The previous paragraph applies in particular to the
":" before a <port> component, the "?" before a <query> component, and the "#" before a <fragment> component.
For the purposes of the above definitions, URLs must be parsed using the URL parsing rules defined in this specification.
| Attribute | Component | Getter Condition | Prefix | Suffix | Setter Preprocessor | Setter Condition |
|---|---|---|---|---|---|---|
protocol
| <scheme> | — | — | U+003A COLON (":")
| Remove all trailing U+003A COLON (":") characters
| The new value is not the empty string |
host
| <hostport> | input is hierarchical and uses a server-based naming authority | — | — | — | The new value is not the empty string and input is hierarchical and uses a server-based naming authority |
hostname
| <host> | input is hierarchical and uses a server-based naming authority | — | — | Remove all leading U+002F SOLIDUS ("/") characters
| The new value is not the empty string and input is hierarchical and uses a server-based naming authority |
port
| <port> | input is hierarchical, uses a server-based naming authority, and contained a <port> component (possibly an empty one) | — | — | Remove any characters in the new value that are not in the range U+0030 DIGIT ZERO .. U+0039 DIGIT NINE. If the resulting string is empty, set it to a single U+0030 DIGIT ZERO character ('0'). | input is hierarchical and uses a server-based naming authority |
pathname
| <path> | input is hierarchical | — | — | If it has no leading U+002F SOLIDUS ("/") character, prepend a U+002F SOLIDUS ("/") character to the new value
| — |
search
| <query> | input is hierarchical, and contained a <query> component (possibly an empty one) | U+003F QUESTION MARK ("?")
| — | Remove one leading U+003F QUESTION MARK ("?") character, if any
| — |
hash
| <fragment> | input contained a <fragment> component (possibly an empty one) | U+0023 NUMBER SIGN ("#")
| — | Remove one leading U+0023 NUMBER SIGN ("#") character, if any
| — |
The table below demonstrates how the getter condition for search results in different results
depending on the exact original syntax of the URL:
| Input URL | search value
| Explanation |
|---|---|---|
http://example.com/
| empty string | No <query> component in input URL. |
http://example.com/?
| ?
| There is a <query> component, but it is empty. The question mark in the resulting value is the prefix. |
http://example.com/?test
| ?test
| The <query> component has the value "test".
|
http://example.com/?test#
| ?test
| The (empty) <fragment> component is not part of the <query> component. |
When a user agent is to fetch a resource, the following steps must be run:
If the resource is identified by the URL
about:blank, then return the empty string
and abort these steps.
Perform the remaining steps asynchronously.
If the resource is identified by an absolute URL, and the resource is to be obtained using a idempotent action (such as an HTTP GET or equivalent), and it is already being downloaded for other reasons (e.g. another invocation of this algorithm), and the user agent is configured such that it is to reuse the data from the existing download instead of initiating a new one, then use the results of the existing download instead of starting a new one.
Otherwise, at a time convenient to the user and the user agent,
download (or otherwise obtain) the resource, applying the
semantics of the relevant specifications (e.g. performing an HTTP
GET or POST operation, or reading the file from disk, following
redirects, dereferencing javascript:
URLs, etc).
For purposes of generating the address of the resource from
which Request-URIs are obtained as required by HTTP for the
Referer (sic) header, the user
agent must use the document's current address of the
appropriate Document as given by this list. [HTTP]
Document.If there are cookies to be set, then the user agent must run the following substeps:
Wait until ownership of the storage mutex can be taken by this instance of the fetching algorithm.
Take ownership of the storage mutex.
Update the cookies. [COOKIES]
Release the storage mutex so that it is once again free.
When the resource is available, or if there is an error of some description, queue a task that uses the resource as appropriate. If the resource can be processed incrementally, as, for instance, with a progressively interlaced JPEG or an HTML file, additional tasks may be queued to process the data as it is downloaded. The task source for these tasks is the networking task source.
The application cache processing model introduces some changes to the networking model to handle the returning of cached resources.
The navigation processing model handles redirects itself, overriding the redirection handling that would be done by the fetching algorithm.
Whether the type sniffing rules apply to the fetched resource depends on the algorithm that invokes the rules — they are not always applicable.
User agents can implement a variety of transfer protocols, but this specification mostly defines behavior in terms of HTTP. [HTTP]
The HTTP GET method is equivalent to the default retrieval action of the protocol. For example, RETR in FTP. Such actions are idempotent and safe, in HTTP terms.
The HTTP response codes are equivalent to statuses in other protocols that have the same basic meanings. For example, a "file not found" error is equivalent to a 404 code, a server error is equivalent to a 5xx code, and so on.
The HTTP headers are equivalent to fields in other protocols that have the same basic meaning. For example, the HTTP authentication headers are equivalent to the authentication aspects of the FTP protocol.
Anything in this specification that refers to HTTP also applies
to HTTP-over-TLS, as represented by URLs
representing the https scheme.
User agents should report certificate errors to the user and must either refuse to download resources sent with erroneous certificates or must act as if such resources were in fact served with no encryption.
Not doing so can result in users not noticing man-in-the-middle attacks.
If a user connects to a server with a self-signed certificate, the user agent could allow the connection but just act as if there had been no encryption. If the user agent instead allowed the user to override the problem and then displayed the page as if it was fully and safely encrypted, the user could be easily tricked into accepting man-in-the-middle connections.
If a user connects to a server with full encryption, but the page then refers to an external resource that has an expired certificate, then the user agent will act as if the resource was unavailable, possibly also reporting the problem to the user. If the user agent instead allowed the resource to be used, then an attacker could just look for "secure" sites that used resources from a different host and only apply man-in-the-middle attacks to that host, for example taking over scripts in the page.
The Content-Type metadata of a resource must be obtained and interpreted in a manner consistent with the requirements of the Content-Type Processing Model specification. [MIMESNIFF]
The algorithm for extracting an encoding from a Content-Type, given a string s, is given in the Content-Type Processing Model specification. It either returns an encoding or nothing. [MIMESNIFF]
The sniffed type of a resource must be found in a manner consistent with the requirements given in the Content-Type Processing Model specification for finding that sniffed type. [MIMESNIFF]
The rules for sniffing images specifically are also defined in the Content-Type Processing Model specification. [MIMESNIFF]
It is imperative that the rules in the Content-Type Processing Model specification be followed exactly. When a user agent uses different heuristics for content type detection than the server expects, security problems can occur. For more details, see the Content-Type Processing Model specification. [MIMESNIFF]
User agents must at a minimum support the UTF-8 and Windows-1252 encodings, but may support more.
It is not unusual for Web browsers to support dozens if not upwards of a hundred distinct character encodings.
User agents must support the preferred MIME name of every character encoding they support that has a preferred MIME name, and should support all the IANA-registered aliases. [IANACHARSET]
When comparing a string specifying a character encoding with the name or alias of a character encoding to determine if they are equal, user agents must use the Charset Alias Matching rules defined in Unicode Technical Standard #22. [UTS22]
For instance, "GB_2312-80" and "g.b.2312(80)" are considered equivalent names.
When a user agent would otherwise use an encoding specified by a label given in the first column of the following table to either convert content to Unicode characters or convert Unicode characters to bytes, it must instead use the encoding given in the cell in the second column of the same row. When a byte or sequence of bytes is treated differently due to this encoding aliasing, it is said to have been misinterpreted for compatibility.
| Input encoding | Replacement encoding | References |
|---|---|---|
| EUC-KR | Windows-949 | [EUCKR] [WIN949] |
| GB2312 | GBK | [RFC1345] [GBK] |
| GB_2312-80 | GBK | [RFC1345] [GBK] |
| ISO-8859-1 | Windows-1252 | [RFC1345] [WIN1252] |
| ISO-8859-9 | Windows-1254 | [RFC1345] [WIN1254] |
| ISO-8859-11 | Windows-874 | [ISO885911] [WIN874] |
| KS_C_5601-1987 | Windows-949 | [RFC1345] [WIN949] |
| Shift_JIS | Windows-31J | [SHIFTJIS] [WIN31J] |
| TIS-620 | Windows-874 | [TIS620] [WIN874] |
| US-ASCII | Windows-1252 | [RFC1345] [WIN1252] |
| x-x-big5 | Big5 | [BIG5] |
The requirement to treat certain encodings as other encodings according to the table above is a willful violation of the W3C Character Model specification, motivated by a desire for compatibility with legacy content. [CHARMOD]
User agents must not support the CESU-8, UTF-7, BOCU-1 and SCSU encodings. [CESU8] [UTF7] [BOCU1] [SCSU]
Support for encodings based on EBCDIC is not recommended. This encoding is rarely used for publicly-facing Web content.
Support for UTF-32 is not recommended. This encoding is rarely used, and frequently implemented incorrectly.
This specification does not make any attempt to support EBCDIC-based encodings and UTF-32 in its algorithms; support and use of these encodings can thus lead to unexpected behavior in implementations of this specification.
Some DOM attributes are defined to reflect a particular content attribute. This means that on getting, the DOM attribute returns the current value of the content attribute, and on setting, the DOM attribute changes the value of the content attribute to the given value.
A list of reflecting DOM attributes and their corresponding content attributes is given in the index.
In general, on getting, if the content attribute is not present, the DOM attribute must act as if the content attribute's value is the empty string; and on setting, if the content attribute is not present, it must first be added.
If a reflecting DOM attribute is a DOMString
attribute whose content attribute is defined to contain a
URL, then on getting, the DOM attribute must resolve the value of the content
attribute relative to the element and return the resulting
absolute URL if that was successful, or the empty
string otherwise; and on setting, must set the content attribute to
the specified literal value. If the content attribute is absent, the
DOM attribute must return the default value, if the content
attribute has one, or else the empty string.
If a reflecting DOM attribute is a DOMString
attribute whose content attribute is defined to contain one or more
URLs, then on getting, the DOM attribute
must split the content
attribute on spaces and return the concatenation of resolving each token URL to an
absolute URL relative to the element, with a single
U+0020 SPACE character between each URL, ignoring any tokens that
did not resolve successfully. If the content attribute is absent,
the DOM attribute must return the default value, if the content
attribute has one, or else the empty string. On setting, the DOM
attribute must set the content attribute to the specified literal
value.
If a reflecting DOM attribute is a DOMString whose
content attribute is an enumerated attribute, and the
DOM attribute is limited to only known values, then, on
getting, the DOM attribute must return the conforming value
associated with the state the attribute is in (in its canonical
case), or the empty string if the attribute is in a state that has
no associated keyword value; and on setting, if the new value is an
ASCII case-insensitive match for one of the keywords
given for that attribute, then the content attribute must be set to
the conforming value associated with the state that the attribute
would be in if set to the given new value, otherwise, if the new
value is the empty string, then the content attribute must be
removed, otherwise, the setter must raise a SYNTAX_ERR
exception.
If a reflecting DOM attribute is a DOMString but
doesn't fall into any of the above categories, then the getting and
setting must be done in a transparent, case-preserving manner.
If a reflecting DOM attribute is a boolean attribute, then on getting the DOM attribute must return true if the attribute is set, and false if it is absent. On setting, the content attribute must be removed if the DOM attribute is set to false, and must be set to have the same value as its name if the DOM attribute is set to true. (This corresponds to the rules for boolean content attributes.)
If a reflecting DOM attribute is a signed integer type
(long) then, on getting, the content attribute must be
parsed according to the rules for parsing signed integers, and if that is
successful, and the value is in the range of the DOM attribute's
type, the resulting value must be returned. If, on the other hand,
it fails or returns an out of range value, or if the attribute is
absent, then the default value must be returned instead, or 0 if
there is no default value. On setting, the given value must be
converted to the shortest possible string representing the number as
a valid integer in base ten and then that string must
be used as the new content attribute value.
If a reflecting DOM attribute is an unsigned integer
type (unsigned long) then, on getting, the content
attribute must be parsed according to the rules for parsing
non-negative integers, and if that is successful, and the
value is in the range of the DOM attribute's type, the resulting
value must be returned. If, on the other hand, it fails or returns
an out of range value, or if the attribute is absent, the default
value must be returned instead, or 0 if there is no default
value. On setting, the given value must be converted to the shortest
possible string representing the number as a valid
non-negative integer in base ten and then that string must be
used as the new content attribute value.
If a reflecting DOM attribute is an unsigned integer type
(unsigned long) that is limited to only positive
non-zero numbers, then the behavior is similar to the previous
case, but zero is not allowed. On getting, the content attribute
must first be parsed according to the rules for parsing
non-negative integers, and if that is successful, and the
value is in the range of the DOM attribute's type, the resulting
value must be returned. If, on the other hand, it fails or returns
an out of range value, or if the attribute is absent, the default
value must be returned instead, or 1 if there is no default
value. On setting, if the value is zero, the user agent must fire an
INDEX_SIZE_ERR exception. Otherwise, the given value
must be converted to the shortest possible string representing the
number as a valid non-negative integer in base ten and
then that string must be used as the new content attribute
value.
If a reflecting DOM attribute is a floating point number type
(float) and it doesn't fall into one of the earlier
categories, then, on getting, the content attribute must be parsed
according to the rules for parsing floating point number
values, and if that is successful, and the value is in the
range of the DOM attribute's type, the resulting value must be
returned. If, on the other hand, it fails or returns an out of range
value, or if the attribute is absent, the default value must be
returned instead, or 0.0 if there is no default value. On setting,
the given value must be converted to the best representation
of the floating point number and then that string must be
used as the new content attribute value.
The values ±Infinity and NaN throw an exception on setting, as defined by Web IDL. [WEBIDL]
If a reflecting DOM attribute is of the type
DOMTokenList or DOMSettableTokenList, then
on getting it must return a DOMTokenList or
DOMSettableTokenList object (as appropriate) whose
underlying string is the element's corresponding content
attribute. When the object mutates its underlying string, the
content attribute must itself be immediately mutated. When the
attribute is absent, then the string represented by the object is
the empty string; when the object mutates this empty string, the
user agent must first add the corresponding content attribute, and
then mutate that attribute instead. The same
DOMTokenList object must be returned every time for
each attribute.
If a reflecting DOM attribute has the type
HTMLElement, or an interface that descends from
HTMLElement, then, on getting, it must run the
following algorithm (stopping at the first point where a value is
returned):
document.getElementById() method would find if it
was passed as its argument the current value of the corresponding
content attribute.On setting, if the given element has an id attribute, then the content attribute must
be set to the value of that id
attribute. Otherwise, the DOM attribute must be set to the empty
string.
The HTMLCollection,
HTMLFormControlsCollection,
HTMLOptionsCollection, and
HTMLPropertyCollection interfaces represent various
lists of DOM nodes. Collectively, objects implementing these
interfaces are called collections.
When a collection is created, a filter and a root are associated with the collection.
For example, when the HTMLCollection
object for the document.images attribute is
created, it is associated with a filter that selects only
img elements, and rooted at the root of the
document.
The collection then represents a live view of the subtree rooted at the collection's root, containing only nodes that match the given filter. The view is linear. In the absence of specific requirements to the contrary, the nodes within the collection must be sorted in tree order.
The rows list is
not in tree order.
An attribute that returns a collection must return the same object every time it is retrieved.
The HTMLCollection interface represents a generic
collection of elements.
[Callable=namedItem] interface HTMLCollection { readonly attribute unsigned long length; [IndexGetter] Element item(in unsigned long index); [NameGetter] Element namedItem(in DOMString name); HTMLCollection tags(in DOMString tagName); };
lengthReturns the number of elements in the collection.
item(index)Returns the item with index index from the collection. The items are sorted in tree order.
Returns null if index is out of range.
namedItem(name)Returns the first item with ID or name name from the collection.
Returns null if no element with that ID or name could be found.
Only a, applet, area,
embed, form, frame,
frameset, iframe, img, and
object elements can have a name for the purpose of
this method; their name is given by the value of their name attribute.
tags(tagName)Returns a collection that is a filtered view of the current collection, containing only elements with the given tag name.
The object's indices of the supported indexed properties are the numbers in the range zero to one less than the number of nodes represented by the collection. If there are no such elements, then there are no supported indexed properties.
The length
attribute must return the number of nodes represented by the
collection.
The item(index) method must return the indexth node in the collection. If there is no indexth node in the collection, then the method must
return null.
The names of the supported named properties consist
of the values of the name attributes of each
a, applet, area,
embed, form, frame,
frameset, iframe, img, and
object element represented by the
collection with a name attribute, plus
the list of IDs that the elements represented by the
collection have.
The namedItem(key) method must return the first node
in the collection that matches the following requirements:
a, applet,
area, embed, form,
frame, frameset, iframe,
img, or object element with a name attribute equal to key,
or,If no such elements are found, then the method must return null.
The tags(tagName) method must return an
HTMLCollection rooted at the same node as the
HTMLCollection object on which the method was invoked,
whose filter matches only HTML elements whose local
name is the tagName argument. In HTML
documents, the argument must first be converted to
ASCII lowercase.
The HTMLFormControlsCollection interface represents
a collection of listed elements in form
and fieldset elements.
[Callable=namedItem] interface HTMLFormControlsCollection { readonly attribute unsigned long length; [IndexGetter] HTMLElement item(in unsigned long index); [NameGetter] Object namedItem(in DOMString name); }; interface RadioNodeList : NodeList { attribute DOMString value; };
lengthReturns the number of elements in the collection.
item(index)Returns the item with index index from the collection. The items are sorted in tree order.
Returns null if index is out of range.
namedItem(name)namedItem(name)Returns the item with ID or name name from the collection.
If there are multiple matching items, then a RadioNodeList object containing all those elements is returned.
Returns null if no element with that ID or name could be found.
Returns the value of the first checked radio button represented by the object.
Can be set, to check the first radio button with the given value represented by the object.
The object's indices of the supported indexed properties are the numbers in the range zero to one less than the number of nodes represented by the collection. If there are no such elements, then there are no supported indexed properties.
The length
attribute must return the number of nodes represented by the
collection.
The item(index) method must return the indexth node in the collection. If there is no indexth node in the collection, then the method must
return null.
The names of the supported named properties consist
of the values of all the id and name attributes of all the elements
represented by the collection.
The namedItem(name) method must act according to the
following algorithm:
id attribute or a name attribute equal to name, then return that node and stop the
algorithm.id attribute or a name attribute equal to name, then return null and stop the algorithm.RadioNodeList object
representing a live view of the
HTMLFormControlsCollection object, further filtered so
that the only nodes in the RadioNodeList object are
those that have either an id attribute
or a name attribute equal to name. The nodes in the RadioNodeList
object must be sorted in tree order.RadioNodeList object.A members of the RadioNodeList interface inherited
from the NodeList interface must behave as they would
on a NodeList object.
The value
DOM attribute on the RadioNodeList object, on getting,
must return the value returned by running the following steps:
Let element be the first element in
tree order represented by the
RadioNodeList object that is an input
element whose type attribute
is in the Radio Button
state and whose checkedness
is true. Otherwise, let it be null.
If element is null, or if it is an
element with no value
attribute, return the empty string.
Otherwise, return the value of element's
value attribute.
On setting, the value DOM attribute must run
the following steps:
Let element be the first element in
tree order represented by the
RadioNodeList object that is an input
element whose type attribute
is in the Radio Button
state and whose value content
attribute is present and equal to the new value, if any. Otherwise,
let it be null.
If element is not null, then set its checkedness to true.
The HTMLOptionsCollection interface represents a
list of option elements. It is always rooted on a
select element and has attributes and methods that
manipulate that element's descendants.
[Callable=namedItem] interface HTMLOptionsCollection { attribute unsigned long length; [IndexGetter] HTMLOptionElement item(in unsigned long index); [NameGetter] Object namedItem(in DOMString name); void add(in HTMLElement element, [Optional] in HTMLElement before); void add(in HTMLElement element, in long before); void remove(in long index); };
length [ = value ]Returns the number of elements in the collection.
When set to a smaller number, truncates the number of option elements in the corresponding container.
When set to a greater number, adds new blank option elements to that container.
item(index)Returns the item with index index from the collection. The items are sorted in tree order.
Returns null if index is out of range.
namedItem(name)Returns the item with ID or name name from the collection.
If there are multiple matching items, then a NodeList object containing all those elements is returned.
Returns null if no element with that ID could be found.
add(element [, before ] )Inserts element before the node given by before.
The before argument can be a number, in which case element is inserted before the item with that number, or an element from the collection, in which case element is inserted before that element.
If before is omitted, null, or a number out of range, then element will be added at the end of the list.
This method will throw a HIERARCHY_REQUEST_ERR
exception if element is an ancestor of the
element into which it is to be inserted. If element is not an option or
optgroup element, then the method does nothing.
The object's indices of the supported indexed properties are the numbers in the range zero to one less than the number of nodes represented by the collection. If there are no such elements, then there are no supported indexed properties.
On getting, the length
attribute must return the number of nodes represented by the
collection.
On setting, the behavior depends on whether the new value is
equal to, greater than, or less than the number of nodes
represented by the collection at that time. If the
number is the same, then setting the attribute must do nothing. If
the new value is greater, then n new
option elements with no attributes and no child nodes
must be appended to the select element on which the
HTMLOptionsCollection is rooted, where n is the difference between the two numbers (new
value minus old value). If the new value is lower, then the last
n nodes in the collection must be removed from
their parent nodes, where n is the difference
between the two numbers (old value minus new value).
Setting length never removes
or adds any optgroup elements, and never adds new
children to existing optgroup elements (though it can
remove children from them).
The item(index) method must return the indexth node in the collection. If there is no indexth node in the collection, then the method must
return null.
The names of the supported named properties consist
of the values of all the id and name attributes of all the elements
represented by the collection.
The namedItem(name) method must act according to the
following algorithm:
id attribute or a name attribute equal to name, then return that node and stop the
algorithm.id attribute or a name attribute equal to name, then return null and stop the algorithm.NodeList object representing a
live view of the HTMLOptionsCollection object, further
filtered so that the only nodes in the NodeList object
are those that have either an id
attribute or a name attribute
equal to name. The nodes in the
NodeList object must be sorted in tree
order.NodeList object.The add(element, before)
method must act according to the following algorithm:
If element is not an option
or optgroup element, then return and abort these
steps.
If element is an ancestor of the
select element on which the
HTMLOptionsCollection is rooted, then throw a
HIERARCHY_REQUEST_ERR exception.
If before is an element, but that
element isn't a descendant of the select element on
which the HTMLOptionsCollection is rooted, then throw
a NOT_FOUND_ERR exception.
If element and before are the same element, then return and abort these steps.
If before is a node, then let reference be that node. Otherwise, if before is an integer, and there is a beforeth node in the collection, let reference be that node. Otherwise, let reference be null.
If reference is not null, let parent be the parent node of reference. Otherwise, let parent
be the select element on which the
HTMLOptionsCollection is rooted.
Act as if the DOM Core insertBefore() method was invoked
on the parent node, with element as the first argument and reference as the second argument.
The remove(index) method must act according to
the following algorithm:
If the number of nodes represented by the collection is zero, abort these steps.
If index is not a number greater than or equal to 0 and less than the number of nodes represented by the collection, let element be the first element in the collection. Otherwise, let element be the indexth element in the collection.
Remove element from its parent node.
The HTMLPropertyCollection interface represents a
collection of elements that add
name-value pairs to a particular item in the microdata
model.
[Callable=namedItem] interface HTMLPropertyCollection { readonly attribute unsigned long length; [IndexGetter] HTMLElement item(in unsigned long index); readonly attribute DOMStringList names; [NameGetter] PropertyNodeList namedItem(in DOMString name); }; typedef sequence<any> PropertyValueArray; interface PropertyNodeList : NodeList { attribute PropertyValueArray content; };
lengthReturns the number of elements in the collection.
namesReturns a DOMStringList with the property names of the elements in the collection.
item(index)Returns the element with index index from the collection. The items are sorted in tree order.
Returns null if index is out of range.
namedItem(name)namedItem(name)Returns a PropertyNodeList object containing any elements that add a property named name.
Returns an array of the various values that the relevant elements have.
The object's indices of the supported indexed properties are the numbers in the range zero to one less than the number of nodes represented by the collection. If there are no such elements, then there are no supported indexed properties.
The length
attribute must return the number of nodes represented by the
collection.
The item(index) method must return the indexth node in the collection. If there is no indexth node in the collection, then the method must
return null.
The names of the supported named properties consist of the property names of all the elements represented by the collection.
The names
attribute must return a live DOMStringList object
giving the property names of all the elements
represented by the collection, listed in tree
order, but with duplicates removed, leaving only the first
occurrence of each name. The same object must be returned each
time.
The namedItem(name) method must return a
PropertyNodeList object representing a live view of the
HTMLPropertyCollection object, further filtered so that
the only nodes in the RadioNodeList object are those
that have a property name equal
to name. The nodes in the
PropertyNodeList object must be sorted in tree
order, and the same object must be returned each time a
particular name is queried.
A members of the PropertyNodeList interface
inherited from the NodeList interface must behave as
they would on a NodeList object.
The content DOM
attribute on the PropertyNodeList object, on getting,
must return a newly constructed DOMStringArray whose
values are the values obtained from the content DOM property of each of the
elements represented by the object, in tree order.
The DOMTokenList interface represents an interface
to an underlying string that consists of an unordered set of
unique space-separated tokens.
While the order of the tokens in the underlying
string is not important, the DOMTokenList interfaces
preserves the underlying order for consistency between
implementations.
[Stringifies] interface DOMTokenList { readonly attribute unsigned long length; [IndexGetter] DOMString item(in unsigned long index); boolean contains(in DOMString token); void add(in DOMString token); void remove(in DOMString token); boolean toggle(in DOMString token); };
lengthReturns the number of tokens in the string.
item(index)Returns the token with index index. The tokens are sorted alphabetically.
Returns null if index is out of range.
contains(token)Returns true if the token is present; false otherwise.
Throws an INVALID_CHARACTER_ERR exception if token contains any spaces.
add(token)Adds token, unless it is already present.
Throws an INVALID_CHARACTER_ERR exception if token contains any spaces.
remove(token)Removes token if it is present.
Throws an INVALID_CHARACTER_ERR exception if token contains any spaces.
toggle(token)Adds token if it is not present, or removes it if it is.
Throws an INVALID_CHARACTER_ERR exception if token contains any spaces.
The length
attribute must return the number of unique tokens that
result from splitting the
underlying string on spaces. This is the length.
The object's indices of the supported indexed properties are the numbers in the range zero to length-1, unless the length is zero, in which case there are no supported indexed properties.
The item(index) method must split the underlying string on spaces,
preserving the order of the tokens as found in the underlying
string, remove instances of exact duplicates other than the first
instance in each case, and then return the indexth item in this list. If index is equal to or greater than the number of
tokens, then the method must return null.
For example, if the string is "a b
a c" then there are three tokens: the token with index 0 is
"a", the token with index 1 is "b", and the token with index 2 is "c".
The contains(token) method must run the following
algorithm:
INVALID_CHARACTER_ERR exception and stop the
algorithm.The add(token) method must run the following
algorithm:
INVALID_CHARACTER_ERR exception and stop the
algorithm.DOMTokenList object's underlying string
then stop the algorithm.DOMTokenList object's underlying
string is not the empty string and the last character of that
string is not a space character, then append a U+0020
SPACE character to the end of that string.DOMTokenList object's underlying string.The remove(token) method must run the following
algorithm:
INVALID_CHARACTER_ERR exception and stop the
algorithm.The toggle(token) method must run the following
algorithm:
INVALID_CHARACTER_ERR exception and stop the
algorithm.DOMTokenList object's underlying string
then remove the given
token from the underlying string, and
stop the algorithm, returning false.DOMTokenList object's underlying
string is not the empty string and the last character of that
string is not a space character, then append a U+0020
SPACE character to the end of that string.DOMTokenList object's underlying string.Objects implementing the DOMTokenList interface must
stringify to the object's
underlying string representation.
The DOMSettableTokenList interface is the same as the
DOMTokenList interface, except that it allows the
underlying string to be directly changed.
[Stringifies] interface DOMSettableTokenList : DOMTokenList { attribute DOMString value; };
valueReturns the underlying string.
Can be set, to change the underlying string.
An object implementing the DOMSettableTokenList
interface must act as defined for the DOMTokenList
interface, except for the value attribute defined
here.
The value
attribute must return the underlying string on getting, and must
replace the underlying string with the new value on setting.
When a user agent is required to obtain a structured clone of an object, it must run the following algorithm, which either returns a separate object, or throws an exception.
Let input be the object being cloned.
Let memory be a list of objects, initially empty. (This is used to catch cycles.)
Let output be the object resulting from calling the internal structured cloning algorithm with input and memory.
Return output.
The internal structured cloning algorithm is always called with two arguments, input and memory, and its behavior depends on the type of input, as follows:
Return the undefined value.
Return the null value.
Return the false value.
Return the true value.
Return a newly constructed Number object with the same value as input.
Return a newly constructed String object with the same value as input.
Date objectReturn a newly constructed Date object with the same value as input.
RegExp objectReturn a newly constructed RegExp object with the same pattern and flags as input.
The value of the lastIndex property is not copied.
ImageData objectReturn a newly constructed ImageData object
with the same width and
height as input, and with a newly constructed
CanvasPixelArray for its data attribute, with the same
length and pixel
values as the input's.
Return the null value.
If input is in memory, then throw a
NOT_SUPPORTED_ERR exception and abort the overall
structured clone algorithm.
Otherwise, let new memory be a list consisting of the items in memory with the addition of input.
Create a new object, output, of the same type as input: either an Array or an Object.
For each enumerable property in input, add a corresponding property to output having the same name, and having a value created from invoking the internal structured cloning algorithm recursively with the value of the property as the "input" argument and new memory as the "memory" argument. The order of the properties in the input and output objects must be the same.
This does not walk the prototype chain.
Return output.
Error)Return the null value.
The DOMStringMap interface represents a set of
name-value pairs. It exposes these using the scripting language's
native mechanisms for property access.
When a DOMStringMap object is instantiated, it is
associated with three algorithms, one for getting the list of
name-value pairs, one for setting names to certain values, and one
for deleting names.
[NameCreator, NameDeleter, NameGetter, NameSetter]
interface DOMStringMap {};
The names of the supported named properties on a
DOMStringMap object at any instant are the names of
each pair returned from the algorithm for getting the list of
name-value pairs at that instant.
When a DOMStringMap object is indexed to retrieve a
named property name, the value returned must be
the value component of the name-value pair whose name component is
name in the list returned by the algorithm for
getting the list of name-value pairs.
When a DOMStringMap object is indexed to create or
modify a named property name with value value, the algorithm for setting names to certain
values must be run, passing name as the name and
the result of converting value to a
DOMString as the value.
When a DOMStringMap object is indexed to delete a
named property named name, the algorithm for
deleting names must be run, passing name as the
name.
The DOMStringMap interface definition
here is only intended for JavaScript environments. Other language
bindings will need to define how DOMStringMap is to be
implemented for those languages.
The dataset attribute on
elements exposes the data-*
attributes on the element.
Given the following fragment and elements with similar constructions:
<img class="tower" id="tower5" data-x="12" data-y="5"
data-ai="robotarget" data-hp="46" data-ability="flames"
src="towers/rocket.png alt="Rocket Tower">
...one could imagine a function splashDamage() that takes some arguments, the first
of which is the element to process:
function splashDamage(node, x, y, damage) {
if (node.classList.contains('tower') && // checking the 'class' attribute
node.dataset.x == x && // reading the 'data-x' attribute
node.dataset.y == y) { // reading the 'data-y' attribute
var hp = parseInt(node.dataset.hp); // reading the 'data-hp' attribute
hp = hp - damage;
if (hp < 0) {
hp = 0;
node.dataset.ai = 'dead'; // setting the 'data-ai' attribute
delete node.dataset.ability; // removing the 'data-ability' attribute
}
node.dataset.hp = hp; // setting the 'data-hp' attribute
}
}
DOM3 Core defines mechanisms for checking for interface support, and for obtaining implementations of interfaces, using feature strings. [DOM3CORE]
A DOM application can use the hasFeature(feature,
version) method of the
DOMImplementation interface with parameter values
"HTML" and "5.0" (respectively)
to determine whether or not this module is supported by the
implementation. In addition to the feature string "HTML", the feature string "XHTML" (with version string "5.0") can
be used to check if the implementation supports XHTML. User agents should respond with a true value when the
hasFeature method is queried with these values.
Authors are cautioned, however, that UAs returning true might not be
perfectly compliant, and that UAs returning false might well have
support for features in this specification; in general, therefore,
use of this method is discouraged.
The values "HTML" and "XHTML" (both with version "5.0") should
also be supported in the context of the getFeature()
and isSupported() methods, as defined by DOM3 Core.
The interfaces defined in this specification are not
always supersets of the interfaces defined in DOM2 HTML; some
features that were formerly deprecated, poorly supported, rarely
used or considered unnecessary have been removed. Therefore it is
not guaranteed that an implementation that supports "HTML" "5.0" also supports "HTML" "2.0".
The following DOMException codes are defined in DOM
Core. [DOMCORE]
INDEX_SIZE_ERRDOMSTRING_SIZE_ERRHIERARCHY_REQUEST_ERRWRONG_DOCUMENT_ERRINVALID_CHARACTER_ERRNO_DATA_ALLOWED_ERRNO_MODIFICATION_ALLOWED_ERRNOT_FOUND_ERRNOT_SUPPORTED_ERRINUSE_ATTRIBUTE_ERRINVALID_STATE_ERRSYNTAX_ERRINVALID_MODIFICATION_ERRNAMESPACE_ERRINVALID_ACCESS_ERRVALIDATION_ERRTYPE_MISMATCH_ERRSECURITY_ERRNETWORK_ERRABORT_ERRURL_MISMATCH_ERRQUOTA_EXCEEDED_ERRDATAGRID_MODEL_ERRPARSE_ERRSERIALISE_ERRThere is an implied strong reference from any DOM attribute that returns a pre-existing object to that object.
For example, the document.location attribute means
that there is a strong reference from a Document
object to its Location object. Similarly, there is
always a strong reference from a Document to any
descendant nodes, and from any node to its owner
Document.
This section is non-normative.
An introduction to marking up a document.
Every XML and HTML document in an HTML UA is represented by a
Document object. [DOM3CORE]
The document's address is an absolute URL
that is set when the Document is created. The
document's current address is an absolute URL
that can change during the lifetime of the Document,
for example when the user navigates to
a fragment identifier on the
page. The document's current address
must be set to the document's address when the
Document is created.
When a Document is created by a script using the createDocument() API, the document's
address is the same as the document's address of
the active document of the script's browsing
context.
Document objects are assumed to be XML
documents unless they are flagged as being HTML
documents when they are created. Whether a document is an
HTML document or an XML document affects the behavior of
certain APIs, as well as a few CSS rendering rules. [CSS]
A Document object created by the createDocument() API on the
DOMImplementation object is initially an XML document, but can be made into an
HTML document by calling document.open() on it.
All Document objects (in user agents implementing
this specification) must also implement
the HTMLDocument interface, available using
binding-specific methods. (This is the case whether or not the
document in question is an HTML
document or indeed whether it contains any HTML
elements at all.) Document objects must also implement the document-level interface
of any other namespaces found in the document that the UA
supports.
For example, if an HTML implementation also
supports SVG, then the Document object implements both
HTMLDocument and SVGDocument.
Because the HTMLDocument interface is
now obtained using binding-specific casting methods instead of
simply being the primary interface of the document object, it is no
longer defined as inheriting from Document.
[NameGetter=OverrideBuiltins, ImplementedOn=Document] interface HTMLDocument { // resource metadata management [PutForwards=href] readonly attribute Location location; readonly attribute DOMString URL; attribute DOMString domain; readonly attribute DOMString referrer; attribute DOMString cookie; readonly attribute DOMString lastModified; readonly attribute DOMString compatMode; attribute DOMString charset; readonly attribute DOMString characterSet; readonly attribute DOMString defaultCharset; readonly attribute DOMString readyState; // DOM tree accessors attribute DOMString title; attribute DOMString dir; attribute HTMLElement body; readonly attribute HTMLCollection images; readonly attribute HTMLCollection embeds; readonly attribute HTMLCollection plugins; readonly attribute HTMLCollection links; readonly attribute HTMLCollection forms; readonly attribute HTMLCollection scripts; readonly attribute HTMLCollection items; NodeList getElementsByName(in DOMString elementName); NodeList getElementsByClassName(in DOMString classNames); // dynamic markup insertion attribute DOMString innerHTML; HTMLDocument open([Optional] in DOMString type, [Optional] in DOMString replace); WindowProxy open(in DOMString url, in DOMString name, in DOMString features, [Optional] in boolean replace); void close(); void write([Variadic] in DOMString text); void writeln([Variadic] in DOMString text); // user interaction Selection getSelection(); readonly attribute Element activeElement; boolean hasFocus(); attribute DOMString designMode; boolean execCommand(in DOMString commandId); boolean execCommand(in DOMString commandId, in boolean showUI); boolean execCommand(in DOMString commandId, in boolean showUI, in DOMString value); boolean queryCommandEnabled(in DOMString commandId); boolean queryCommandIndeterm(in DOMString commandId); boolean queryCommandState(in DOMString commandId); boolean queryCommandSupported(in DOMString commandId); DOMString queryCommandValue(in DOMString commandId); readonly attribute HTMLCollection commands; // event handler DOM attributes attribute Function onabort; attribute Function onblur; attribute Function oncanplay; attribute Function oncanplaythrough; attribute Function onchange; attribute Function onclick; attribute Function oncontextmenu; attribute Function ondblclick; attribute Function ondrag; attribute Function ondragend; attribute Function ondragenter; attribute Function ondragleave; attribute Function ondragover; attribute Function ondragstart; attribute Function ondrop; attribute Function ondurationchange; attribute Function onemptied; attribute Function onended; attribute Function onerror; attribute Function onfocus; attribute Function onformchange; attribute Function onforminput; attribute Function oninput; attribute Function oninvalid; attribute Function onkeydown; attribute Function onkeypress; attribute Function onkeyup; attribute Function onload; attribute Function onloadeddata; attribute Function onloadedmetadata; attribute Function onloadstart; attribute Function onmousedown; attribute Function onmousemove; attribute Function onmouseout; attribute Function onmouseover; attribute Function onmouseup; attribute Function onmousewheel; attribute Function onpause; attribute Function onplay; attribute Function onplaying; attribute Function onprogress; attribute Function onratechange; attribute Function onreadystatechange; attribute Function onscroll; attribute Function onseeked; attribute Function onseeking; attribute Function onselect; attribute Function onshow; attribute Function onstalled; attribute Function onsubmit; attribute Function onsuspend; attribute Function ontimeupdate; attribute Function onvolumechange; attribute Function onwaiting; };
Since the HTMLDocument interface holds methods and
attributes related to a number of disparate features, the members of
this interface are described in various different sections.
User agents must raise a
SECURITY_ERR exception whenever any of the members of
an HTMLDocument object are accessed by scripts whose
effective script origin is not the same as the Document's effective
script origin.
URLReturns the document's address.
referrerReturns the
address of the Document from which the user
navigated to this one, unless it was blocked or there was no such
document, in which case it returns the empty string.
The noreferrer link
type can be used to block the referrer.
The URL
attribute must return the document's address.
The referrer attribute
must return either the current address of the active document
of the source browsing context at the time the
navigation was started (that is, the page which navigated the browsing context
to the current document), or the empty string if there is no such
originating page, or if the UA has been configured not to report
referrers in this case, or if the navigation was initiated for a
hyperlink with a noreferrer keyword.
In the case of HTTP, the referrer DOM attribute will
match the Referer (sic) header
that was sent when fetching the current
page.
Typically user agents are configured to not report
referrers in the case where the referrer uses an encrypted protocol
and the current page does not (e.g. when navigating from an https: page to an http:
page).
cookie [ = value ]Returns the HTTP cookies that apply to the
Document. If there are no cookies or cookies can't be
applied to this resource, the empty string will be returned.
Can be set, to add a new cookie to the element's set of HTTP cookies.
If the Document has no browsing
context an INVALID_STATE_ERR exception will be
thrown. If the contents are sandboxed into a unique origin, a
SECURITY_ERR exception will be thrown.
The cookie
attribute represents the cookies of the resource.
On getting, if the document is not associated
with a browsing context then the user agent must raise
an INVALID_STATE_ERR exception. Otherwise, if the
sandboxed origin browsing context flag was set on the
browsing context of the Document when the
Document was created, the user agent must raise a
SECURITY_ERR exception. Otherwise, if the
document's address does not use a server-based naming
authority, it must return the empty string. Otherwise, it must first
obtain the storage mutex and then return the same
string as the value of the Cookie HTTP header
it would include if fetching the resource
indicated by the document's address over HTTP, as per
RFC 2109 section 4.3.4 or later specifications, excluding HTTP-only
cookies. [RFC2109] [RFC2965]
On setting, if the document is not associated with a
browsing context then the user agent must raise an
INVALID_STATE_ERR exception. Otherwise, if the
sandboxed origin browsing context flag was set on the
browsing context of the Document when the
Document was created, the user agent must raise a
SECURITY_ERR exception. Otherwise, if the
document's address does not use a server-based naming
authority, it must do nothing. Otherwise, the user agent must
obtain the storage mutex and then act as it would when
processing cookies if it had just attempted to fetch
the document's address over HTTP, and had received a
response with a Set-Cookie header whose value was the
specified value, as per RFC 2109 sections 4.3.1, 4.3.2, and 4.3.3 or
later specifications, but without overwriting the values of
HTTP-only cookies. [RFC2109] [RFC2965]
This specification does not define what makes an
HTTP-only cookie, and at the time of publication the editor is not
aware of any reference for HTTP-only cookies. They are a feature
supported by some Web browsers wherein an "httponly" parameter added to the cookie string
causes the cookie to be hidden from script.
Since the cookie attribute is accessible
across frames, the path restrictions on cookies are only a tool to
help manage which cookies are sent to which parts of the site, and
are not in any way a security feature.
lastModifiedReturns the date of the last modification to the document, as
reported by the server, in the form "MM/DD/YYYY hh:mm:ss".
If the last modification date is not known, the current time is returned instead.
The lastModified
attribute, on getting, must return the date and time of the
Document's source file's last modification, in the
user's local time zone, in the following format:
All the numeric components above, other than the year, must be given as two digits in the range U+0030 DIGIT ZERO to U+0039 DIGIT NINE representing the number in base ten, zero-padded if necessary. The year must be given as four or more digits in the range U+0030 DIGIT ZERO to U+0039 DIGIT NINE representing the number in base ten, zero-padded if necessary.
The Document's source file's last modification date
and time must be derived from relevant features of the networking
protocols used, e.g. from the value of the HTTP Last-Modified header of the document, or from
metadata in the file system for local files. If the last
modification date and time are not known, the attribute must return
the current date and time in the above format.
compatModeIn a conforming document, returns the string "CSS1Compat". (In quirks mode
documents, returns the string "BackCompat",
but a conforming document can never trigger quirks
mode.)
A Document is always set to one of three modes:
no quirks mode, the default; quirks mode, used
typically for legacy documents; and limited quirks mode,
also known as "almost standards" mode. The mode is only ever changed
from the default by the HTML parser, based on the
presence, absence, or value of the DOCTYPE string.
The compatMode DOM
attribute must return the literal string "CSS1Compat" unless the document has been set to
quirks mode by the HTML parser, in which
case it must instead return the literal string "BackCompat".
charset [ = value ]Returns the document's character encoding.
Can be set, to dynamically change the document's character encoding.
New values that are not IANA-registered aliases supported by the user agent are ignored.
characterSetReturns the document's character encoding.
defaultCharsetReturns what might be the user agent's default character encoding.
Documents have an associated character encoding. When a Document
object is created, the document's character encoding
must be initialized to UTF-16. Various algorithms during page
loading affect this value, as does the charset setter. [IANACHARSET]
The charset
DOM attribute must, on getting, return the preferred MIME name of
the document's character encoding. On setting, if the
new value is an IANA-registered alias for a character encoding
supported by the user agent, the document's character
encoding must be set to that character encoding. (Otherwise,
nothing happens.)
The characterSet
DOM attribute must, on getting, return the preferred MIME name of
the document's character encoding.
The defaultCharset
DOM attribute must, on getting, return the preferred MIME name of a
character encoding, possibly the user's default encoding, or an
encoding associated with the user's current geographical location,
or any arbitrary encoding name.
readyStateReturns "loading" while the Document is loading, and "complete" once it has loaded.
The readystatechange event fires on the Document object when this value changes.
Each document has a current document readiness. When a
Document object is created, it must have its
current document readiness set to the string "loading"
if the document is associated with an HTML parser or an
XML parser, or to the string "complete"
otherwise. Various algorithms during page loading affect this
value. When the value is set, the user agent must fire a
simple event called readystatechange at the
Document object.
A Document is said to have an active
parser if it is associated with an HTML parser or
an XML parser that has not yet been stopped or aborted.
The readyState DOM
attribute must, on getting, return the current document
readiness.
The html element of a document is the
document's root element, if there is one and it's an
html element, or null otherwise.
The head element of a document is the
first head element that is a child of the
html element, if there is one, or null
otherwise.
title [ = value ]Returns the document's title, as given by the
title element.
Can be set, to update the document's title. If there is no
head element,
the new value is ignored.
In SVG documents, the SVGDocument interface's
title attribute takes
precedence.
The title element of a document is the
first title element in the document (in tree order), if
there is one, or null otherwise.
The title attribute must,
on getting, run the following algorithm:
If the root element is an svg
element in the "http://www.w3.org/2000/svg"
namespace, and the user agent supports SVG, then return the value
that would have been returned by the DOM attribute of the same name
on the SVGDocument interface. [SVG]
Otherwise, let value be a concatenation
of the data of all the child text
nodes of the title element, in
tree order, or the empty string if the title
element is null.
Replace any sequence of two or more consecutive space characters in value with a single U+0020 SPACE character.
Remove any leading or trailing space characters in value.
Return value.
On setting, the following algorithm must be run. Mutation events must be fired as appropriate.
If the root element is an svg
element in the "http://www.w3.org/2000/svg"
namespace, and the user agent supports SVG, then the setter must
defer to the setter for the DOM attribute of the same name on the
SVGDocument interface (if it is readonly, then this
will raise an exception). Stop the algorithm here. [SVG]
title element is null and
the head element is null, then the
attribute must do nothing. Stop the algorithm here.title element is null, then a
new title element must be created and appended to
the head element.title element (if
any) must all be removed.Text node whose data is the new value
being assigned must be appended to the title
element.The title attribute on
the HTMLDocument interface should shadow the attribute
of the same name on the SVGDocument interface when the
user agent supports both HTML and SVG. [SVG]
body [ = value ]Returns the body element.
Can be set, to replace the body element.
If the new value is not a body or frameset element, this will throw a HIERARCHY_REQUEST_ERR exception.
The body element of a document is the first child of
the html element that is either a
body element or a frameset element. If
there is no such element, it is null. If the body
element is null, then when the specification requires that events be
fired at "the body element", they must instead be fired at the
Document object.
The body
attribute, on getting, must return the body element of
the document (either a body element, a
frameset element, or null). On setting, the following
algorithm must be run:
body or
frameset element, then raise a
HIERARCHY_REQUEST_ERR exception and abort these
steps.replaceChild() method had been
called with the new value and the
incumbent body element as its two arguments respectively,
then abort these steps.imagesReturns an HTMLCollection of the img elements in the Document.
embedspluginsReturn an HTMLCollection of the embed elements in the Document.
linksReturns an HTMLCollection of the a and area elements in the Document that have href attributes.
formsReturn an HTMLCollection of the form elements in the Document.
scriptsReturn an HTMLCollection of the script elements in the Document.
The images
attribute must return an HTMLCollection rooted at the
Document node, whose filter matches only
img elements.
The embeds
attribute must return an HTMLCollection rooted at the
Document node, whose filter matches only
embed elements.
The plugins
attribute must return the same object as that returned by the embeds attribute.
The links
attribute must return an HTMLCollection rooted at the
Document node, whose filter matches only a
elements with href
attributes and area elements with href attributes.
The forms
attribute must return an HTMLCollection rooted at the
Document node, whose filter matches only
form elements.
The scripts
attribute must return an HTMLCollection rooted at the
Document node, whose filter matches only
script elements.
getElementsByName(name)Returns a NodeList of a,
applet, button, form,
frame, frameset, iframe,
img, input, map,
meta, object, select, and textarea elements in the
Document that have a name
attribute with the value name.
getElementsByClassName(classes)getElementsByClassName(classes)Returns a NodeList of the elements in the object
on which the method was invoked (a Document or an
Element) that have all the classes given by classes.
The classes argument is interpreted as a space-separated list of classes.
The getElementsByName(name) method takes a string name, and must return a live NodeList
containing all the a, applet,
button, form, frame,
frameset, iframe, img,
input, map, meta,
object,
select, and textarea elements in that
document that have a name attribute whose
value is equal to the name argument (in a
case-sensitive manner), in tree order.
The getElementsByClassName(classNames) method takes a string that
contains an unordered set of unique space-separated
tokens representing classes. When called, the method must
return a live NodeList object containing all the
elements in the document, in tree order, that have all
the classes specified in that argument, having obtained the classes
by splitting a string on
spaces. If there are no tokens specified in the argument,
then the method must return an empty NodeList. If the
document is in quirks mode, then the comparisons for
the classes must be done in an ASCII case-insensitive
manner, otherwise, the comparisons must be done in a
case-sensitive manner.
The getElementsByClassName(classNames) method on the
HTMLElement interface must return a live
NodeList with the nodes that the
HTMLDocument getElementsByClassName()
method would return when passed the same argument(s), excluding any
elements that are not descendants of the HTMLElement
object on which the method was invoked.
HTML, SVG, and MathML elements define which classes they are in
by having an attribute in the per-element partition with the name
class containing a space-separated list of
classes to which the element belongs. Other specifications may also
allow elements in their namespaces to be labeled as being in
specific classes.
Given the following XHTML fragment:
<div id="example"> <p id="p1" class="aaa bbb"/> <p id="p2" class="aaa ccc"/> <p id="p3" class="bbb ccc"/> </div>
A call to
document.getElementById('example').getElementsByClassName('aaa')
would return a NodeList with the two paragraphs
p1 and p2 in it.
A call to getElementsByClassName('ccc bbb')
would only return one node, however, namely p3. A call
to
document.getElementById('example').getElementsByClassName('bbb ccc ')
would return the same thing.
A call to getElementsByClassName('aaa,bbb') would
return no nodes; none of the elements above are in the "aaa,bbb"
class.
The HTMLDocument interface supports named properties. The names
of the supported named properties at any moment consist of
the values of the name content
attributes of all the applet, embed,
form, iframe, img, and
fallback-free object elements in the
Document that have name
content attributes, and the values of the id content attributes of all the
applet and fallback-free
object elements in the Document that have
id content attributes, and the values
of the id content attributes of all the
img elements in the Document that have
both name content attributes and
id content attributes.
When the
HTMLDocument object is indexed for property
retrieval using a name name, then the user
agent must return the value obtained using the following steps:
Let elements be the list of named elements with
the name name in the Document.
There will be at least one such element, by definition.
If elements has only one element, and that
element is an iframe element, then return the
WindowProxy object of the nested browsing
context represented by that iframe element,
and abort these steps.
Otherwise, if elements has only one element, return that element and abort these steps.
Otherwise return an HTMLCollection rooted at the
Document node, whose filter matches only named elements with
the name name.
Named elements with the name name, for the purposes of the above algorithm, are those that are either:
applet, embed, form,
iframe, img, or
fallback-free object elements that have a
name content attribute whose value
is name, orapplet or fallback-free
object elements that have an id content attribute whose value is name, orimg elements that have an id content attribute whose value is name, and that have a name content attribute present also.An object element is said to be
fallback-free if it has no object or
embed descendants.
The dir
attribute on the HTMLDocument interface is defined
along with the dir content
attribute.
Elements, attributes, and attribute values in HTML are defined
(by this specification) to have certain meanings (semantics). For
example, the ol element represents an ordered list, and
the lang attribute represents the
language of the content.
Authors must not use elements, attributes, and attribute values for purposes other than their appropriate intended semantic purpose. Authors must not use elements, attributes, and attribute values that are not permitted by this specification or other applicable specifications.
For example, the following document is non-conforming, despite being syntactically correct:
<!DOCTYPE html>
<html lang="en-GB">
<head> <title> Demonstration </title> </head>
<body>
<table>
<tr> <td> My favourite animal is the cat. </td> </tr>
<tr>
<td>
—<a href="http://example.org/~ernest/"><cite>Ernest</cite></a>,
in an essay from 1992
</td>
</tr>
</table>
</body>
</html>
...because the data placed in the cells is clearly not tabular
data (and the cite element mis-used). A corrected
version of this document might be:
<!DOCTYPE html> <html lang="en-GB"> <head> <title> Demonstration </title> </head> <body> <blockquote> <p> My favourite animal is the cat. </p> </blockquote> <p> —<a href="http://example.org/~ernest/">Ernest</a>, in an essay from 1992 </p> </body> </html>
This next document fragment, intended to represent the heading of a corporate site, is similarly non-conforming because the second line is not intended to be a heading of a subsection, but merely a subheading or subtitle (a subordinate heading for the same section).
<body> <h1>ABC Company</h1> <h2>Leading the way in widget design since 1432</h2> ...
The hgroup element should be used in these kinds of
situations:
<body> <hgroup> <h1>ABC Company</h1> <h2>Leading the way in widget design since 1432</h2> </hgroup> ...
In the next example, there is a non-conforming attribute value ("carpet") and a non-conforming attribute ("texture"), which is not permitted by this specification:
<label>Carpet: <input type="carpet" name="c" texture="deep pile"></label>
Here would be an alternative and correct way to mark this up:
<label>Carpet: <input type="text" class="carpet" name="c" data-texture="deep pile"></label>
Through scripting and using other mechanisms, the values of attributes, text, and indeed the entire structure of the document may change dynamically while a user agent is processing it. The semantics of a document at an instant in time are those represented by the state of the document at that instant in time, and the semantics of a document can therefore change over time. User agents must update their presentation of the document as this occurs.
HTML has a progress element that
describes a progress bar. If its "value" attribute is dynamically
updated by a script, the UA would update the rendering to show the
progress changing.
The nodes representing HTML elements in the DOM must implement, and expose to scripts, the interfaces listed for them in the relevant sections of this specification. This includes HTML elements in XML documents, even when those documents are in another context (e.g. inside an XSLT transform).
Elements in the DOM represent things; that is, they have intrinsic meaning, also known as semantics.
For example, an ol element
represents an ordered list.
The basic interface, from which all the HTML
elements' interfaces inherit, and which
must be used by elements that have no additional
requirements, is the HTMLElement interface.
interface HTMLElement : Element { // DOM tree accessors NodeList getElementsByClassName(in DOMString classNames); // dynamic markup insertion attribute DOMString innerHTML; attribute DOMString outerHTML; void insertAdjacentHTML(in DOMString position, in DOMString text); // metadata attributes attribute DOMString id; attribute DOMString title; attribute DOMString lang; attribute DOMString dir; attribute DOMString className; readonly attribute DOMTokenList classList; readonly attribute DOMStringMap dataset; // microdata [PutForwards=value] readonly attribute DOMSettableTokenList item; [PutForwards=value] readonly attribute DOMSettableTokenList itemprop; readonly attribute HTMLPropertyCollection properties; attribute DOMString content; attribute HTMLElement subject; // user interaction attribute boolean hidden; void click(); void scrollIntoView(); void scrollIntoView(in boolean top); attribute long tabIndex; void focus(); void blur(); attribute DOMString accessKey; readonly attribute DOMString accessKeyLabel; attribute boolean draggable; attribute DOMString contentEditable; readonly attribute boolean isContentEditable; attribute HTMLMenuElement contextMenu; attribute boolean spellcheck; // command API readonly attribute DOMString commandType; readonly attribute DOMString label; readonly attribute DOMString icon; readonly attribute boolean disabled; readonly attribute boolean checked; // styling readonly attribute CSSStyleDeclaration style; // event handler DOM attributes attribute Function onabort; attribute Function onblur; attribute Function oncanplay; attribute Function oncanplaythrough; attribute Function onchange; attribute Function onclick; attribute Function oncontextmenu; attribute Function ondblclick; attribute Function ondrag; attribute Function ondragend; attribute Function ondragenter; attribute Function ondragleave; attribute Function ondragover; attribute Function ondragstart; attribute Function ondrop; attribute Function ondurationchange; attribute Function onemptied; attribute Function onended; attribute Function onerror; attribute Function onfocus; attribute Function onformchange; attribute Function onforminput; attribute Function oninput; attribute Function oninvalid; attribute Function onkeydown; attribute Function onkeypress; attribute Function onkeyup; attribute Function onload; attribute Function onloadeddata; attribute Function onloadedmetadata; attribute Function onloadstart; attribute Function onmousedown; attribute Function onmousemove; attribute Function onmouseout; attribute Function onmouseover; attribute Function onmouseup; attribute Function onmousewheel; attribute Function onpause; attribute Function onplay; attribute Function onplaying; attribute Function onprogress; attribute Function onratechange; attribute Function onreadystatechange; attribute Function onscroll; attribute Function onseeked; attribute Function onseeking; attribute Function onselect; attribute Function onshow; attribute Function onstalled; attribute Function onsubmit; attribute Function onsuspend; attribute Function ontimeupdate; attribute Function onvolumechange; attribute Function onwaiting; };
The HTMLElement interface holds methods and
attributes related to a number of disparate features, and the
members of this interface are therefore described in various
different sections of this specification.
The following attributes are common to and may be specified on all HTML elements (even those not defined in this specification):
accesskeyclasscontenteditablecontextmenudirdraggableiditemhiddenlangitempropspellcheckstylesubjecttabindextitleIn addition, unless otherwise specified, the following event handler content attributes may be specified on any HTML element:
onabortonblur*oncanplayoncanplaythroughonchangeonclickoncontextmenuondblclickondragondragendondragenterondragleaveondragoverondragstartondropondurationchangeonemptiedonendedonerror*onfocus*onformchangeonforminputoninputoninvalidonkeydownonkeypressonkeyuponload*onloadeddataonloadedmetadataonloadstartonmousedownonmousemoveonmouseoutonmouseoveronmouseuponmousewheelonpauseonplayonplayingonprogressonratechangeonreadystatechangeonscrollonseekedonseekingonselectonshowonstalledonsubmitonsuspendontimeupdateonvolumechangeonwaitingThe attributes marked with an asterisk cannot be
specified on body elements as those elements expose
event handler attributes of the Window object with the same
names.
Also, custom data
attributes (e.g. data-foldername or
data-msgid) can be specified on any HTML element, to store custom data
specific to the page.
In HTML documents, elements in the HTML
namespace may have an xmlns attribute
specified, if, and only if, it has the exact value
"http://www.w3.org/1999/xhtml". This does not apply to
XML documents.
In HTML, the xmlns attribute
has absolutely no effect. It is basically a talisman. It is allowed
merely to make migration to and from XHTML mildly easier. When
parsed by an HTML parser, the attribute ends up in no
namespace, not the "http://www.w3.org/2000/xmlns/"
namespace like namespace declaration attributes in XML do.
In XML, an xmlns attribute is
part of the namespace declaration mechanism, and an element cannot
actually have an xmlns attribute in no
namespace specified.
id attributeThe id attribute
represents its element's unique identifier. The value
must be unique in the element's home subtree and must
contain at least one character. The value must not contain any space characters.
If the value is not the empty string, user agents must associate
the element with the given value (exactly, including any space
characters) for the purposes of ID matching within the element's
home subtree (e.g. for selectors in CSS or for the
getElementById() method in the DOM).
Identifiers are opaque strings. Particular meanings should not be
derived from the value of the id
attribute.
This specification doesn't preclude an element having multiple
IDs, if other mechanisms (e.g. DOM Core methods) can set an
element's ID in a way that doesn't conflict with the id attribute.
The id DOM attribute must
reflect the id content
attribute.
title attributeThe title attribute
represents advisory information for the element, such
as would be appropriate for a tooltip. On a link, this could be the
title or a description of the target resource; on an image, it could
be the image credit or a description of the image; on a paragraph,
it could be a footnote or commentary on the text; on a citation, it
could be further information about the source; and so forth. The
value is text.
If this attribute is omitted from an element, then it implies
that the title attribute of the
nearest ancestor HTML element
with a title attribute set is also
relevant to this element. Setting the attribute overrides this,
explicitly stating that the advisory information of any ancestors is
not relevant to this element. Setting the attribute to the empty
string indicates that the element has no advisory information.
If the title attribute's value
contains U+000A LINE FEED (LF) characters, the content is split into
multiple lines. Each U+000A LINE FEED (LF) character represents a
line break.
Caution is advised with respect to the use of newlines in title attributes.
For instance, the following snippet actually defines an abbreviation's expansion with a line break in it:
<p>My logs show that there was some interest in <abbr title="Hypertext Transport Protocol">HTTP</abbr> today.</p>
Some elements, such as link, abbr, and
input, define additional semantics for the title attribute beyond the semantics
described above.
The title DOM attribute
must reflect the title
content attribute.
lang and xml:lang attributesThe lang attribute (in
no namespace) specifies the primary language for the
element's contents and for any of the element's attributes that
contain text. Its value must be a valid RFC 3066 language code, or
the empty string. [RFC3066]
The lang
attribute in the XML namespace is defined in XML. [XML]
If these attributes are omitted from an element, then the language of this element is the same as the language of its parent element, if any. Setting the attribute to the empty string indicates that the primary language is unknown.
The lang attribute in no namespace
may be used on any HTML
element.
The lang
attribute in the XML namespace may be used on
HTML elements in XML documents, as well as
elements in other namespaces if the relevant specifications allow it
(in particular, MathML and SVG allow lang attributes in the
XML namespace to be specified on their
elements). If both the lang attribute
in no namespace and the lang attribute in the XML
namespace are specified on the same element, they must
have exactly the same value when compared in an ASCII
case-insensitive manner.
Authors must not use the lang attribute in the XML
namespace in HTML documents. To ease
migration to and from XHTML, authors may specify an attribute in no
namespace with no prefix and with the literal localname "xml:lang" on HTML elements in
HTML documents, but such attributes must only be
specified if a lang attribute in no
namespace is also specified, and both attributes must have the same
value when compared in an ASCII case-insensitive
manner.
To determine the language of a node, user agents must look at the
nearest ancestor element (including the element itself if the node
is an element) that has a lang attribute in the XML
namespace set or is an HTML element and has a lang in no namespace attribute set. That
attribute specifies the language of the node.
If both the lang attribute in no
namespace and the lang attribute in the XML
namespace are set on an element, user agents must use
the lang attribute
in the XML namespace, and the lang attribute in no namespace must be
ignored for the purposes of determining
the element's language.
If no explicit language is given for the root element, but there is a document-wide default language set, then that is the language of the node.
If there is no document-wide default language, then language information from a higher-level protocol (such as HTTP), if any, must be used as the final fallback language. In the absence of any language information, the default value is unknown (the empty string).
If the resulting value is not a recognized language code, then it must be treated as an unknown language (as if the value was the empty string).
User agents may use the element's language to determine proper processing or rendering (e.g. in the selection of appropriate fonts or pronunciations, or for dictionary selection).
The lang DOM attribute
must reflect the lang
content attribute in no namespace.
xml:base
attribute (XML only)The xml:base attribute is
defined in XML Base. [XMLBASE]
The xml:base attribute may be
used on elements of XML documents. Authors must not
use the xml:base attribute in
HTML documents.
dir attributeThe dir attribute specifies the
element's text directionality. The attribute is an enumerated
attribute with the keyword ltr mapping
to the state ltr, and the keyword rtl
mapping to the state rtl. The attribute has no
defaults.
The processing of this attribute is primarily performed by the presentation layer. For example, the rendering section in this specification defines a mapping from this attribute to the CSS 'direction' and 'unicode-bidi' properties, and CSS defines rendering in terms of those properties.
The directionality of an element, which is used in
particular by the canvas element's text rendering API,
is either 'ltr' or 'rtl'. If the user agent supports CSS and the
'direction' property on this element has a computed value of either
'ltr' or 'rtl', then that is the directionality of the
element. Otherwise, if the element is being rendered, then the
directionality of the element is the directionality used by
the presentation layer, potentially determined from the value of the
dir attribute on the
element. Otherwise, if the element's dir attribute has the state ltr, the
element's directionality is 'ltr' (left-to-right); if the attribute
has the state rtl, the element's directionality is 'rtl'
(right-to-left); and otherwise, the element's directionality is the
same as its parent element, or 'ltr' if there is no parent
element.
dir [ = value ]Returns the html element's dir attribute's value, if any.
Can be set, to either "ltr" or "rtl", to replace the html element's dir attribute's value.
If there is no html element, returns the empty string and ignores new values.
The dir DOM attribute on
an element must reflect the dir content attribute of that element,
limited to only known values.
The dir DOM
attribute on HTMLDocument objects must
reflect the dir content
attribute of the html element, if any,
limited to only known values. If there is no such
element, then the attribute must return the empty string and do
nothing on setting.
Authors are strongly encouraged to use the dir attribute to indicate text direction
rather than using CSS, since that way their documents will continue
to render correctly even in the absence of CSS (e.g. as interpreted
by search engines).
class attributeEvery HTML element may have a
class attribute specified.
The attribute, if specified, must have a value that is an unordered set of unique space-separated tokens representing the various classes that the element belongs to.
The classes that an HTML
element has assigned to it consists of all the classes
returned when the value of the class
attribute is split on
spaces.
Assigning classes to an element affects class
matching in selectors in CSS, the getElementsByClassName()
method in the DOM, and other such features.
Authors may use any value in the class attribute, but are encouraged to use
the values that describe the nature of the content, rather than
values that describe the desired presentation of the
content.
The className and
classList DOM
attributes must both reflect the class content attribute.
style attributeAll elements may have the style
content attribute set. If specified, the attribute must contain only
a list of zero or more semicolon-separated (;) CSS declarations. [CSS]
In user agents that support CSS, the attribute's value must be parsed when the attribute is added or has its value changed, with its value treated as the body (the part inside the curly brackets) of a declaration block in a rule whose selector matches just the element on which the attribute is set. All URLs in the value must be resolved relative to the element when the attribute is parsed. For the purposes of the CSS cascade, the attribute must be considered to be a 'style' attribute at the author level.
Documents that use style
attributes on any of their elements must still be comprehensible and
usable if those attributes were removed.
In particular, using the style attribute to hide and show content,
or to convey meaning that is otherwise not included in the document,
is non-conforming. (To hide and show content, use the hidden attribute.)
styleReturns a CSSStyleDeclaration object for the element's style attribute.
The style DOM attribute
must return a CSSStyleDeclaration whose value
represents the declarations specified in the attribute, if
present. Mutating the CSSStyleDeclaration object must
create a style attribute on the
element (if there isn't one already) and then change its value to be
a value representing the serialized form of the
CSSStyleDeclaration object. [CSSOM]
In the following example, the words that refer to colors are
marked up using the span element and the style attribute to make those words show
up in the relevant colors in visual media.
<p>My sweat suit is <span style="color: green; background: transparent">green</span> and my eyes are <span style="color: blue; background: transparent">blue</span>.</p>
A custom data attribute is an attribute in no
namespace whose name starts with the string "data-", has at least one
character after the hyphen, is XML-compatible, and
contains no characters in the range U+0041 .. U+005A (LATIN CAPITAL
LETTER A .. LATIN CAPITAL LETTER Z).
All attributes in HTML documents get lowercased automatically, so the restriction on uppercase letters doesn't affect such documents.
Custom data attributes are intended to store custom data private to the page or application, for which there are no more appropriate attributes or elements.
These attributes are not intended for use by software that is independent of the site that uses the attributes.
For instance, a site about music could annotate list items representing tracks in an album with custom data attributes containing the length of each track. This information could then be used by the site itself to allow the user to sort the list by track length, or to filter the list for tracks of certain lengths.
<ol> <li data-length="2m11s">Beyond The Sea</li> ... </ol>
It would be inappropriate, however, for the user to use generic software not associated with that music site to search for tracks of a certain length by looking at this data.
This is because these attributes are intended for use by the site's own scripts, and are not a generic extension mechanism for publicly-usable metadata.
Every HTML element may have any number of custom data attributes specified, with any value.
datasetReturns a DOMStringMap object for the element's data-* attributes.
The dataset DOM
attribute provides convenient accessors for all the data-* attributes on an element. On
getting, the dataset DOM attribute
must return a DOMStringMap object, associated with the
following algorithms, which expose these attributes on their
element:
data-", add a
name-value pair to list whose name is the
attribute's name with the first five character removed and whose
value is the attribute's value.data- and the name passed to the
algorithm.setAttribute() would have raised an
exception when setting an attribute with the name name, then this must raise the same
exception.data- and the name passed to the
algorithm.If a Web page wanted an element to represent a space ship,
e.g. as part of a game, it would have to use the class attribute along with data-* attributes:
<div class="spaceship" data-id="92432"
data-weapons="laser 2" data-shields="50%"
data-x="30" data-y="10" data-z="90">
<button class="fire"
onclick="spaceships[this.parentNode.dataset.id].fire()">
Fire
</button>
</div>
Authors should carefully design such extensions so that when the attributes are ignored and any associated CSS dropped, the page is still usable.
User agents must not derive any implementation behavior from these attributes or values. Specifications intended for user agents must not define these attributes to have any meaningful values.
All the elements in this specification have a defined content model, which describes what nodes are allowed inside the elements, and thus what the structure of an HTML document or fragment must look like.
As noted in the conformance and terminology
sections, for the purposes of determining if an element matches its
content model or not, CDATASection nodes in the DOM are treated as
equivalent to Text nodes, and entity reference nodes are treated as if
they were expanded in place.
The space characters are always allowed between elements. User agents represent these characters between elements in the source markup as text nodes in the DOM. Empty text nodes and text nodes consisting of just sequences of those characters are considered inter-element whitespace.
Inter-element whitespace, comment nodes, and processing instruction nodes must be ignored when establishing whether an element matches its content model or not, and must be ignored when following algorithms that define document and element semantics.
An element A is said to be preceded or followed by a second element B if A and B have the same parent node and there are no other element nodes or text nodes (other than inter-element whitespace) between them.
Authors must not use elements in the HTML namespace anywhere except where they are explicitly allowed, as defined for each element, or as explicitly required by other specifications. For XML compound documents, these contexts could be inside elements from other namespaces, if those elements are defined as providing the relevant contexts.
The Atom specification defines the Atom content element, when its type attribute has the value xhtml, as requiring that it contains a single HTML
div element. Thus, a div element is
allowed in that context, even though this is not explicitly
normatively stated by this specification. [ATOM]
In addition, elements in the HTML namespace may be orphan nodes (i.e. without a parent node).
For example, creating a td element and storing it
in a global variable in a script is conforming, even though
td elements are otherwise only supposed to be used
inside tr elements.
var data = {
name: "Banana",
cell: document.createElement('td'),
};
Each element in HTML falls into zero or more categories that group elements with similar characteristics together. The following broad categories are used in this specification:
These categories are related as follows:
In addition, certain elements are categorized as form-associated elements and further subcategorized to define their role in various form-related processing models.
Some elements have unique requirements and do not fit into any particular category.
Metadata content is content that sets up the presentation or behavior of the rest of the content, or that sets up the relationship of the document with other documents, or that conveys other "out of band" information.
basecommandlinkmetanoscriptscriptstyletitleElements from other namespaces whose semantics are primarily metadata-related (e.g. RDF) are also metadata content.
Thus, in the XML serialization, one can use RDF, like this:
<html xmlns="http://www.w3.org/1999/xhtml"
xmlns:r="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
<head>
<title>Hedral's Home Page</title>
<r:RDF>
<Person xmlns="http://www.w3.org/2000/10/swap/pim/contact#"
r:about="http://hedral.example.com/#">
<fullName>Cat Hedral</fullName>
<mailbox r:resource="mailto:hedral@damowmow.com"/>
<personalTitle>Sir</personalTitle>
</Person>
</r:RDF>
</head>
<body>
<h1>My home page</h1>
<p>I like playing with string, I guess. Sister says squirrels are fun
too so sometimes I follow her to play with them.</p>
</body>
</html>
This isn't possible in the HTML serialization, however.
Most elements that are used in the body of documents and applications are categorized as flow content.
aabbraddressarea (if it is a descendant of a map element)articleasideaudiobbbbdoblockquotebrbuttoncanvascitecodecommanddatagriddatalistdeldetailsdfndialogdivdlemembedfieldsetfigurefooterformh1h2h3h4h5h6headerhgrouphriiframeimginputinskbdkeygenlabellink (if the itemprop attribute is present)mapmarkmathmenumeta (if the itemprop attribute is present)meternavnoscriptobjectoloutputppreprogressqrubysampscriptsectionselectsmallspanstrongstyle (if the scoped attribute is present)subsupsvgtabletextareatimeulvarvideoAs a general rule, elements whose content model allows any
flow content should have either at least one descendant
text node that is not inter-element
whitespace, or at least one descendant element node that is
embedded content. For the purposes of this requirement,
del elements and their descendants must not be counted
as contributing to the ancestors of the del
element.
This requirement is not a hard requirement, however, as there are many cases where an element can be empty legitimately, for example when it is used as a placeholder which will later be filled in by a script, or when the element is part of a template and would on most pages be filled in but on some pages is not relevant.
Sectioning content is content that defines the scope of headings and footers.
articleasidenavsectionEach sectioning content element potentially has a heading and an outline. See the section on headings and sections for further details.
There are also certain elements that are sectioning roots. These are distinct from sectioning content, but they can also have an outline.
Heading content defines the header of a section (whether explicitly marked up using sectioning content elements, or implied by the heading content itself).
h1h2h3h4h5h6hgroupPhrasing content is the text of the document, as well as elements that mark up that text at the intra-paragraph level. Runs of phrasing content form paragraphs.
a (if it contains only phrasing content)abbr (if it is a descendant of a map element)areaaudiobbbbdobrbuttoncanvascitecodecommanddatalistdel (if it contains only phrasing content)dfnemembediiframeimginputins (if it contains only phrasing content)kbdkeygenlabellink (if the itemprop attribute is present)map (if it contains only phrasing content)markmathmeta (if the itemprop attribute is present)meternoscriptobjectoutputprogressqrubysampscriptselectsmallspanstrongsubsupsvgtextareatimevarvideoAs a general rule, elements whose content model allows any
phrasing content should have either at least one
descendant text node that is not inter-element
whitespace, or at least one descendant element node that is
embedded content. For the purposes of this requirement,
nodes that are descendants of del elements must not be
counted as contributing to the ancestors of the del
element.
Most elements that are categorized as phrasing content can only contain elements that are themselves categorized as phrasing content, not any flow content.
Text, in the context of content models, means text nodes. Text is sometimes used as a content model on its own, but is also phrasing content, and can be inter-element whitespace (if the text nodes are empty or contain just space characters).
Embedded content is content that imports another resource into the document, or content from another vocabulary that is inserted into the document.
audiocanvasembediframeimgmathobjectsvgvideoElements that are from namespaces other than the HTML namespace and that convey content but not metadata, are embedded content for the purposes of the content models defined in this specification. (For example, MathML, or SVG.)
Some embedded content elements can have fallback content: content that is to be used when the external resource cannot be used (e.g. because it is of an unsupported format). The element definitions state what the fallback is, if any.
Interactive content is content that is specifically intended for user interaction.
aaudio (if the controls attribute is present)bbbuttondatagriddetailsembedimg (if the usemap attribute is present)input (if the type attribute is not in the Hidden state)keygenlabelmenu (if the type attribute is in the tool bar state)object (if the usemap attribute is present)selecttextareavideo (if the controls attribute is present)Certain elements in HTML have an activation
behavior, which means that the user can activate them. This
triggers a sequence of events dependent on the activation mechanism,
and normally culminating in a click
event followed by a DOMActivate event, as described below.
The user agent should allow the user to manually trigger elements that have an activation behavior, for instance using keyboard or voice input, or through mouse clicks. When the user triggers an element with a defined activation behavior in a manner other than clicking it, the default action of the interaction event must be to run synthetic click activation steps on the element.
When a user agent is to run synthetic click activation
steps on an element, the user agent must run pre-click
activation steps on the element, then fire a click event at the element. The
default action of this click event
must be to run post-click activation steps on the
element. If the event is canceled, the user agent must run
canceled activation steps on the element instead.
Given an element target, the nearest activatable element is the element returned by the following algorithm:
If target has a defined activation behavior, then return target and abort these steps.
If target has a parent element, then set target to that parent element and return to the first step.
Otherwise, there is no nearest activatable element.
When a pointing device is clicked, the user agent must run these steps:
Let e be the nearest activatable element of the element designated by the user, if any.
If there is an element e, run pre-click activation steps on it.
Dispatching the required click
event.
If there is an element e, then the default action of the click event must be to run post-click activation steps on element e.
If there is an element e but the event is canceled, the user agent must run canceled activation steps on element e.
The above doesn't happen for arbitrary synthetic
events dispatched by author script. However, the click() method can be used to make it
happen programmatically.
When a user agent is to run pre-click activation steps on an element, it must run the pre-click activation steps defined for that element, if any.
When a user agent is to run post-click activation
steps on an element, the user agent must fire a simple
event called DOMActivate that is cancelable at
that element. The default action of this event must be to run
final activation steps on that element. If the event is
canceled, the user agent must run canceled activation
steps on the element instead.
When a user agent is to run canceled activation steps on an element, it must run the canceled activation steps defined for that element, if any.
When a user agent is to run final activation steps on
an element, it must run the activation behavior defined
for that element. Activation behaviors can refer to the click and DOMActivate events that were fired
by the steps above leading up to this point.
Some elements are described as transparent; they have "transparent" in the description of their content model.
When a content model includes a part that is "transparent", those parts must not contain content that would not be conformant if all transparent elements in the tree were replaced, in their parent element, by the children in the "transparent" part of their content model, retaining order.
When a transparent element has no parent, then the part of its content model that is "transparent" must instead be treated as accepting any flow content.
The term paragraph as defined in this
section is distinct from (though related to) the p
element defined later. The paragraph concept defined
here is used to describe how to interpret documents.
A paragraph is typically a run of phrasing content that forms a block of text with one or more sentences that discuss a particular topic, as in typography, but can also be used for more general thematic grouping. For instance, an address is also a paragraph, as is a part of a form, a byline, or a stanza in a poem.
In the following example, there are two paragraphs in a section. There is also a heading, which contains phrasing content that is not a paragraph. Note how the comments and inter-element whitespace do not form paragraphs.
<section> <h1>Example of paragraphs</h1> This is the <em>first</em> paragraph in this example. <p>This is the second.</p> <!-- This is not a paragraph. --> </section>
Paragraphs in flow content are defined relative to
what the document looks like without the a,
ins, del, and map elements
complicating matters, since those elements, with their hybrid
content models, can straddle paragraph boundaries, as shown in the
first two examples below.
Generally, having elements straddle paragraph boundaries is best avoided. Maintaining such markup can be difficult.
The following example takes the markup from the earlier example
and puts ins and del elements around some
of the markup to show that the text was changed (though in this
case, the changes admittedly don't make much sense). Notice how
this example has exactly the same paragraphs as the previous one,
despite the ins and del elements —
the ins element straddles the heading and the first
paragraph, and the del element straddles the boundary
between the two paragraphs.
<section> <ins><h1>Example of paragraphs</h1> This is the <em>first</em> paragraph in</ins> this example<del>. <p>This is the second.</p></del> <!-- This is not a paragraph. --> </section>
Let view be a view of the DOM that replaces
all a, ins, del, and
map elements in the document with their contents. Then,
in view, for each run of sibling phrasing
content nodes uninterrupted by other types of content, in an
element that accepts content other than phrasing
content, let first be the first node of
the run, and let last be the last node of the
run. For each such run that consists of at least one node that is
neither embedded content nor inter-element
whitespace, a paragraph exists in the original DOM from
immediately before first to immediately after
last. (Paragraphs can thus span across
a, ins, del, and
map elements.)
Conformance checkers may warn authors of cases where they have
paragraphs that overlap each other (this can happen with
object, video, audio, and
canvas elements).
A paragraph is also formed explicitly by
p elements.
The p element can be used to wrap
individual paragraphs when there would otherwise not be any content
other than phrasing content to separate the paragraphs from each
other.
In the following example, the link spans half of the first paragraph, all of the heading separating the two paragraphs, and half of the second paragraph. It straddles the paragraphs and the heading.
<aside> Welcome! <a href="about.html"> This is home of... <h1>The Falcons!</h1> The Lockheed Martin multirole jet fighter aircraft! </a> This page discusses the F-16 Fighting Falcon's innermost secrets. </aside>
Here is another way of marking this up, this time showing the paragraphs explicitly, and splitting the one link element into three:
<aside> <p>Welcome! <a href="about.html">This is home of...</a></p> <h1><a href="about.html">The Falcons!</a></h1> <p><a href="about.html">The Lockheed Martin multirole jet fighter aircraft!</a> This page discusses the F-16 Fighting Falcon's innermost secrets.</p> </aside>
It is possible for paragraphs to overlap when using certain elements that define fallback content. For example, in the following section:
<section> <h1>My Cats</h1> You can play with my cat simulator. <object data="cats.sim"> To see the cat simulator, use one of the following links: <ul> <li><a href="cats.sim">Download simulator file</a> <li><a href="http://sims.example.com/watch?v=LYds5xY4INU">Use online simulator</a> </ul> Alternatively, upgrade to the Mellblom Browser. </object> I'm quite proud of it. </section>
There are five paragraphs:
object element.The first paragraph is overlapped by the other four. A user agent that supports the "cats.sim" resource will only show the first one, but a user agent that shows the fallback will confusingly show the first sentence of the first paragraph as if it was in the same paragraph as the second one, and will show the last paragraph as if it was at the start of the second sentence of the first paragraph.
To avoid this confusion, explicit p elements can be
used.
For HTML documents, and for HTML elements in HTML documents, certain APIs defined in DOM3 Core become case-insensitive or case-changing, as sometimes defined in DOM3 Core, and as summarized or required below. [DOM3CORE].
This does not apply to XML documents or to elements that are not in the HTML namespace despite being in HTML documents.
Element.tagName and Node.nodeNameThese attributes must return element names converted to ASCII uppercase, regardless of the case with which they were created.
Document.createElement()The canonical form of HTML markup is all-lowercase; thus, this method will lowercase the argument before creating the requisite element. Also, the element created must be in the HTML namespace.
This doesn't apply to Document.createElementNS(). Thus, it is possible,
by passing this last method a tag name in the wrong case, to
create an element that claims to have the tag name of an element
defined in this specification, but doesn't support its interfaces,
because it really has another tag name not accessible from the DOM
APIs.
Element.setAttribute()Element.setAttributeNode()Attribute names are converted to ASCII lowercase.
Specifically: when an attribute is set on an HTML element using Element.setAttribute(), the name argument must be
converted to ASCII lowercase before the element is
affected; and when an Attr node is set on an HTML element using Element.setAttributeNode(), it must have its name
converted to ASCII lowercase before the element is
affected.
This doesn't apply to Document.setAttributeNS() and Document.setAttributeNodeNS().
Element.getAttribute()Element.getAttributeNode()Attribute names are converted to ASCII lowercase.
Specifically: When the Element.getAttribute() method or the Element.getAttributeNode() method is invoked on
an HTML element, the name
argument must be converted to ASCII lowercase before the
element's attributes are examined.
This doesn't apply to Document.getAttributeNS() and Document.getAttributeNodeNS().
Document.getElementsByTagName()Element.getElementsByTagName()HTML elements match by lower-casing the argument before comparison, elements from other namespaces are treated as in XML (case-sensitively).
Specifically, these methods (but not their namespaced counterparts) must compare the given argument in a case-sensitive manner, but when looking at HTML elements, the argument must first be converted to ASCII lowercase.
Thus, in an HTML document with nodes in multiple namespaces, these methods will effectively be both case-sensitive and case-insensitive at the same time.
Implementations of XPath 1.0 that
operate on HTML documents parsed or created in the manners described
in this specification (e.g. as part of the document.evaluate() API) are affected as
follows:
In addition to the cases where a name expression would match a node per XPath 1.0, a name expression must evaluate to matching a node when all the following conditions are also met:
These requirements are a willful violation of the XPath 1.0 specification, motivated by desire to have implementations be compatible with legacy content while still supporting the changes that this specification introduces to HTML regarding which namespace is used for HTML elements. [XPATH10]
XSLT 1.0 processors outputting to a DOM when the output method is "html" (either explicitly or via the defaulting rule in XSLT 1.0) are affected as follows:
If the transformation program outputs an element in no namespace, the processor must, prior to constructing the corresponding DOM element node, change the namespace of the element to the HTML namespace, ASCII-lowercase the element's local name, and ASCII-lowercase the names of any non-namespaced attributes on the element.
This requirement is a willful violation of the XSLT 1.0 specification, required because this specification changes the namespaces and case-sensitivity rules of HTML in a manner that would otherwise be incompatible with DOM-based XSLT transformations. (Processors that serialize the output are unaffected.) [XSLT10]
APIs for dynamically inserting markup into the document interact with the parser, and thus their behavior, varies depending on whether they are used with HTML documents (and the HTML parser) or XHTML in XML documents (and the XML parser).
The open()
method comes in several variants with different numbers of
arguments.
open( [ type [, replace ] ] )Causes the Document to be replaced in-place, as if
it was a new Document object, but reusing the
previous object, which is then returned.
If the type argument is omitted or has the
value "text/html", then the resulting
Document has an HTML parser associated with it, which
can be given data to parse using document.write(). Otherwise, all
content passed to document.write() will be parsed
as plain text.
If the replace argument is absent or false,
a new entry is added to the session history to represent this
entry, and the previous entries for this Document are
all collapsed into one entry with a new Document
object.
The method has no effect if the Document is still
being parsed.
open( url, name, features [, replace ] )Works like the window.open()
method.
close()Closes the input stream that was opened by the document.open() method.
When called with two or fewer arguments, the method must act as follows:
Let type be the value of the first
argument, if there is one, or "text/html"
otherwise.
Let replace be true if there is a second argument and it is an ASCII case-insensitive match for the value "replace", and false otherwise.
If the document has an active parser that isn't a
script-created parser, and the insertion
point associated with that parser's input
stream is not undefined (that is, it does point to
somewhere in the input stream), then the method does
nothing. Abort these steps and return the Document
object on which the method was invoked.
This basically causes document.open() to be ignored
when it's called in an inline script found during the parsing of
data sent over the network, while still letting it have an effect
when called asynchronously or on a document that is itself being
spoon-fed using these APIs.
Unload the
Document object, with the recycle
parameter set to true. If the user refused to allow the
document to be unloaded, then these steps must be
aborted.
If the document has an active parser, then abort that parser, and throw away any pending content in the input stream.
Unregister all event listeners registered on the
Document node and its descendants.
Remove any tasks
associated with the Document in any task
source.
Remove all child nodes of the document, without firing any mutation events.
Replace the Document's singleton objects with
new instances of those objects. (This includes in particular the
Window, Location, History,
ApplicationCache, UndoManager,
Navigator, and Selection objects, the
various BarProp objects, the two Storage
objects, and the various HTMLCollection objects. It
also includes all the Web IDL prototypes in the JavaScript binding,
including the Document object's prototype.)
Change the document's character encoding to UTF-16.
Change the document's address to the first script's browsing context's active document's address.
Create a new HTML parser and associate it with
the document. This is a script-created parser (meaning
that it can be closed by the document.open() and document.close() methods, and
that the tokenizer will wait for an explicit call to document.close() before emitting
an end-of-file token). The encoding confidence is
irrelevant.
If the type string contains a U+003B SEMICOLON (;) character, remove the first such character and all characters from it up to the end of the string.
Strip all leading and trailing space characters from type.
If type is not now an ASCII
case-insensitive match for the string
"text/html", then act as if the tokenizer had emitted
a start tag token with the tag name "pre", then set the HTML
parser's tokenization stage's content
model flag to PLAINTEXT.
If replace is false, then:
Document's History objectDocumentDocument object, as well as the state of
the document at the start of these steps. (This allows the user
to step backwards in the session history to see the page before
it was blown away by the document.open() call.)Finally, set the insertion point to point at just before the end of the input stream (which at this point will be empty).
Return the Document on which the method was
invoked.
When called with three or more arguments, the open() method on the
HTMLDocument object must call the open() method on the Window
object of the HTMLDocument object, with the same
arguments as the original call to the open() method, and return whatever
that method returned. If the HTMLDocument object has no
Window object, then the method must raise an
INVALID_ACCESS_ERR exception.
The close()
method must do nothing if there is no script-created
parser associated with the document. If there is such a
parser, then, when the method is called, the user agent must insert
an explicit "EOF" character at the end of the parser's
input stream.
document.write()write(text...)Adds the given string(s) to the Document's input
stream. If necessary, calls the open() method implicitly
first.
This method throws an INVALID_ACCESS_ERR exception
when invoked on XML documents.
The document.write(...)
method must act as follows:
If the method was invoked on an XML
document, throw an INVALID_ACCESS_ERR
exception and abort these steps.
If the insertion point is undefined, the open() method must be called
(with no arguments) on the document
object. If the user refused to allow the document to be
unloaded, then these steps must be aborted. Otherwise, the
insertion point will point at just before the end of
the (empty) input stream.
The string consisting of the concatenation of all the arguments to the method must be inserted into the input stream just before the insertion point.
If there is a pending external script, then the method must now return without further processing of the input stream.
Otherwise, the tokenizer must process the characters that were
inserted, one at a time, processing resulting tokens as they are
emitted, and stopping when the tokenizer reaches the insertion
point or when the processing of the tokenizer is aborted by the
tree construction stage (this can happen if a script
end tag token is emitted by the tokenizer).
If the document.write() method was
called from script executing inline (i.e. executing because the
parser parsed a set of script tags), then this is a
reentrant invocation of the
parser.
Finally, the method must return.
document.writeln()writeln(text...)Adds the given string(s) to the Document's input
stream, followed by a newline character. If necessary, calls the
open() method implicitly
first.
This method throws an INVALID_ACCESS_ERR exception
when invoked on XML documents.
The document.writeln(...)
method, when invoked, must act as if the document.write() method had been
invoked with the same argument(s), plus an extra argument consisting
of a string containing a single line feed character (U+000A).
innerHTMLThe innerHTML DOM
attribute represents the markup of the node's contents.
innerHTML [ = value ]Returns a fragment of HTML or XML that represents the
Document.
Can be set, to replace the Document's contents
with the result of parsing the given string.
In the case of XML documents, will throw a
SYNTAX_ERR if the Document cannot be
serialized to XML, or if the given string is not well-formed.
innerHTML [ = value ]Returns a fragment of HTML or XML that represents the element's contents.
Can be set, to replace the contents of the element with nodes parsed from the given string.
In the case of XML documents, will throw a
SYNTAX_ERR if the element cannot be serialized to
XML, or if the given string is not well-formed.
On getting, if the node's document is an HTML document, then the attribute must return the result of running the HTML fragment serialization algorithm on the node; otherwise, the node's document is an XML document, and the attribute must return the result of running the XML fragment serialization algorithm on the node instead (this might raise an exception instead of returning a string).
On setting, the following steps must be run:
If the node's document is an HTML document: Invoke the HTML fragment parsing algorithm.
If the node's document is an XML document: Invoke the XML fragment parsing algorithm.
In either case, the algorithm must be invoked with the string
being assigned into the innerHTML attribute as the input. If the node is an Element
node, then, in addition, that element must be passed as the context element.
If this raises an exception, then abort these steps.
Otherwise, let new children be the nodes returned.
If the attribute is being set on a Document node,
and that document has an active parser, then abort
that parser.
Remove the child nodes of the node whose innerHTML attribute is being set,
firing appropriate mutation events.
If the attribute is being set on a Document
node, let target document be that
Document node. Otherwise, the attribute is being
set on an Element node; let target
document be the ownerDocument of
that Element.
Set the ownerDocument of all the nodes in
new children to the target
document.
Append all the new children nodes to the
node whose innerHTML attribute
is being set, preserving their order, and firing mutation events
as appropriate.
outerHTMLThe outerHTML DOM
attribute represents the markup of the element and its contents.
outerHTML [ = value ]Returns a fragment of HTML or XML that represents the element and its contents.
Can be set, to replace the element with nodes parsed from the given string.
In the case of XML documents, will throw a
SYNTAX_ERR if the element cannot be serialized to
XML, or if the given string is not well-formed.
On getting, if the node's document is an HTML document, then the attribute must return the result of running the HTML fragment serialization algorithm on a fictional node whose only child is the node on which the attribute was invoked; otherwise, the node's document is an XML document, and the attribute must return the result of running the XML fragment serialization algorithm on that fictional node instead (this might raise an exception instead of returning a string).
On setting, the following steps must be run:
Let target be the element whose outerHTML attribute is being
set.
If target has no parent node, then abort these steps. There would be no way to obtain a reference to the nodes created even if the remaining steps were run.
If target's parent node is a
Document object, throw a
NO_MODIFICATION_ALLOWED_ERR exception and abort these
steps.
Let parent be target's
parent node, unless that is a DocumentFragment node,
in which case let parent be an arbitrary
body element.
If target's document is an HTML document: Invoke the HTML fragment parsing algorithm.
If target's document is an XML document: Invoke the XML fragment parsing algorithm.
In either case, the algorithm must be invoked with the string
being assigned into the outerHTML attribute as the input, and parent as the context element.
If this raises an exception, then abort these steps.
Otherwise, let new children be targets returned.
Set the ownerDocument of all the nodes in
new children to target's
document.
Remove target from its parent node, firing mutation events as appropriate, and then insert in its place all the new children nodes, preserving their order, and again firing mutation events as appropriate.
insertAdjacentHTML()insertAdjacentHTML(position, text)Parsed the given string text as HTML or XML and inserts the resulting nodes into the tree in the position given by the position argument, as follows:
Throws a SYNTAX_ERR exception the arguments have
invalid values (e.g., in the case of XML documents,
if the given string is not well-formed).
Throws a NO_MODIFICATION_ALLOWED_ERR exception if
the given position isn't possible (e.g. inserting elements after
the root element of a Document).
The insertAdjacentHTML(position, text)
method, when invoked, must run the following algorithm:
Let position and text be the method's first and second arguments, respectively.
Let target be the element on which the method was invoked.
Use the first matching item from this list:
If target has no parent node, then abort these steps.
If target's parent node is a
Document object, then throw a
NO_MODIFICATION_ALLOWED_ERR exception and abort
these steps.
Otherwise, let context be the parent node of target.
Let context be the same as target.
Throw a SYNTAX_ERR exception.
If target's document is an HTML document: Invoke the HTML fragment parsing algorithm.
If target's document is an XML document: Invoke the XML fragment parsing algorithm.
In either case, the algorithm must be invoked with text as the input, and the element selected in by the previous step as the context element.
If this raises an exception, then abort these steps.
Otherwise, let new children be targets returned.
Set the ownerDocument of all the nodes in
new children to target's
document.
Use the first matching item from this list:
Insert all the new children nodes immediately before target.
Insert all the new children nodes before the first child of target, if there is one. If there is no such child, append them all to target.
Append all the new children nodes to target.
Insert all the new children nodes immediately after target.
The new children nodes must be inserted in a manner that preserves their order and fires mutation events as appropriate.
html elementhead element followed by a body element.manifestinterface HTMLHtmlElement : HTMLElement {};
The html element represents the root of
an HTML document.
The manifest
attribute gives the address of the document's application
cache manifest, if there is
one. If the attribute is present, the attribute's value must be a
valid URL.
The manifest attribute
only has an effect during
the early stages of document load. Changing the attribute
dynamically thus has no effect (and thus, no DOM API is provided for
this attribute).
For the purposes of application cache selection,
later base elements cannot affect the resolving of relative URLs in manifest attributes, as the
attributes are processed before those elements are seen.
head elementhtml element.title element.interface HTMLHeadElement : HTMLElement {};
The head element represents a
collection of metadata for the Document.
title elementhead element containing no other title elements.interface HTMLTitleElement : HTMLElement { attribute DOMString text; };
The title element represents the
document's title or name. Authors should use titles that identify
their documents even when they are used out of context, for example
in a user's history or bookmarks, or in search results. The
document's title is often different from its first heading, since the
first heading does not have to stand alone when taken out of
context.
There must be no more than one title element per
document.
The title element must not contain any
elements.
The text DOM
attribute must return the same value as the textContent
DOM attribute on the element.
Here are some examples of appropriate titles, contrasted with the top-level headings that might be used on those same pages.
<title>Introduction to The Mating Rituals of Bees</title>
...
<h1>Introduction</h1>
<p>This companion guide to the highly successful
<cite>Introduction to Medieval Bee-Keeping</cite> book is...
The next page might be a part of the same site. Note how the title describes the subject matter unambiguously, while the first heading assumes the reader knows what the context is and therefore won't wonder if the dances are Salsa or Waltz:
<title>Dances used during bee mating rituals</title>
...
<h1>The Dances</h1>
The string to use as the document's title is given by the document.title DOM
attribute. User agents should use the document's
title when referring to the document in their user
interface.
base elementhead element containing no other base elements.hreftargetinterface HTMLBaseElement : HTMLElement { attribute DOMString href; attribute DOMString target; };
The base element allows authors to specify the
document base URL for the purposes of resolving relative URLs, and the name
of the default browsing context for the purposes of
following hyperlinks. The element does not represent any content beyond this
information.
There must be no more than one base element per
document.
A base element must have either an href attribute, a target attribute, or both.
The href content
attribute, if specified, must contain a valid URL.
A base element, if it has an href attribute, must come before any
other elements in the tree that have attributes defined as taking
URLs, except the html element
(its manifest attribute
isn't affected by base elements).
If there are multiple base elements
with href attributes, all but the
first are ignored.
The target
attribute, if specified, must contain a valid browsing context
name or keyword, which specifies which browsing
context is to be used as the default when hyperlinks and forms in the Document cause navigation.
A base element, if it has a target attribute, must come before
any elements in the tree that represent hyperlinks.
If there are multiple base elements
with target attributes, all but
the first are ignored.
The href and target DOM attributes
must reflect the respective content attributes of the
same name.
link elementitemprop attribute is present: flow content.itemprop attribute is present: phrasing content.noscript element that is a child of a head element.itemprop attribute is present: where phrasing content is expected.hrefrelmediahreflangtypesizestitle attribute has special semantics on this element.interface HTMLLinkElement : HTMLElement { attribute boolean disabled; attribute DOMString href; attribute DOMString rel; readonly attribute DOMTokenList relList; attribute DOMString media; attribute DOMString hreflang; attribute DOMString type; attribute DOMString sizes; };
The LinkStyle interface must also be implemented
by this element, the styling processing model defines
how. [CSSOM]
The link element allows authors to link their
document to other resources.
The destination of the link(s) is given by the href attribute, which must
be present and must contain a valid URL. If the href attribute is absent, then the
element does not define a link.
The types of link indicated (the relationships) are given by the
value of the rel
attribute, which must be present, and must have a value that is a
set of space-separated tokens. The allowed values and their meanings are defined
in a later section. If the rel
attribute is absent, or if the values used are not allowed according
to the definitions in this specification, then the element does not
define a link.
Two categories of links can be created using the
link element. Links
to external resources are links to resources that are to be
used to augment the current document, and hyperlink links are links to
other documents. The link types
section defines whether a particular link type is an external
resource or a hyperlink. One element can create multiple links (of
which some might be external resource links and some might be
hyperlinks); exactly which and how many links are created depends on
the keywords given in the rel
attribute. User agents must process the links on a per-link basis,
not a per-element basis.
Each link is handled separately. For instance, if
there are two link elements with rel="stylesheet", they each count as a separate
external resource, and each is affected by its own attributes
independently.
The exact behavior for links to external resources depends on the
exact relationship, as defined for the relevant link type. Some of
the attributes control whether or not the external resource is to be
applied (as defined below). For external
resources that are represented in the DOM (for example, style
sheets), the DOM representation must be made available even if the
resource is not applied. To obtain the resource, the user agent must
resolve the URL
given by the href attribute,
relative to the element, and then fetch the resulting
absolute URL. User agents may opt to only
fetch such resources when they are needed, instead of
pro-actively fetching all the external
resources that are not applied.
The semantics of the protocol used (e.g. HTTP) must be followed when fetching external resources. (For example, redirects must be followed and 404 responses must cause the external resource to not be applied.)
Fetching external resources must delay the load event of the element's document until the task that is queued by the networking task source once the resource has been fetched (defined below) has been run.
The task that is queued by the networking task
source once the resource has been fetched must, if the loads were successful,
queue a task to fire a simple event called
load at the link
element; otherwise, if the resource or one of its subresources
failed to completely load for any reason (e.g. DNS error, HTTP 404
response, a connection being prematurely closed, unsupported
Content-Type), it must instead queue a task to
fire a simple event called error at the link
element. Non-network errors in processing the resource or its
subresources (e.g. CSS parse errors, PNG decoding errors) are not
failures for the purposes of this paragraph.
The task source for these tasks is the DOM manipulation task source.
Interactive user agents should provide users with a means to
follow the hyperlinks
created using the link element, somewhere within their
user interface. The exact interface is not defined by this
specification, but it should include the following information
(obtained from the element's attributes, again as defined below), in
some form or another (possibly simplified), for each hyperlink
created with each link element in the document:
rel attribute)title attribute).href attribute).hreflang attribute).media attribute).User agents may also include other information, such as the type
of the resource (as given by the type attribute).
Hyperlinks created with the link
element and its rel attribute
apply to the whole page. This contrasts with the rel attribute of a
and area elements, which indicates the type of a link
whose context is given by the link's location within the
document.
The media
attribute says which media the resource applies to. The value must
be a valid media query. [MQ]
If the link is a hyperlink
then the media attribute is
purely advisory, and describes for which media the document in
question was designed.
However, if the link is an external resource link,
then the media attribute is
prescriptive. The user agent must apply the external resource to
views while their state match the listed
media and the other relevant conditions apply, and must not apply
them otherwise.
The external resource might have further
restrictions defined within that limit its applicability. For
example, a CSS style sheet might have some @media blocks. This specification does not override
such further restrictions or requirements.
The default, if the media attribute is omitted, is
all, meaning that by default links apply to all
media.
The hreflang
attribute on the link element has the same semantics as
the hreflang
attribute on hyperlink elements.
The type attribute
gives the MIME type of the linked resource. It is purely advisory.
The value must be a valid MIME type, optionally with parameters. [RFC2046]
For external resource
links, the type attribute
is used as a hint to user agents so that they can avoid fetching
resources they do not support. If the attribute
is present, then the user agent must assume that the resource is of
the given type. If the attribute is omitted, but the external
resource link type has a default type defined, then the user agent
must assume that the resource is of that type. If the UA does not
support the given MIME type for the given link relationship, then
the UA should not fetch the resource; if the UA does support the
given MIME type for the given link relationship, then the UA should
fetch the resource. If the attribute is omitted, and
the external resource link type does not have a default type
defined, but the user agent would fetch the resource if the type was
known and supported, then the user agent should fetch
the resource under the assumption that it will be
supported.
User agents must not consider the type attribute authoritative —
upon fetching the resource, user agents must not use the type attribute to determine its actual
type. Only the actual type (as defined in the next paragraph) is
used to determine whether to apply the resource, not the
aforementioned assumed type.
If the external resource link type defines rules for processing the resource's Content-Type metadata, then those rules apply. Otherwise, if the resource is expected to be an image, user agents may apply the image sniffing rules, with the official type being the type determined from the resource's Content-Type metadata, and use the resulting sniffed type of the resource as if it was the actual type. Otherwise, if neither of these conditions apply or if the user agent opts not to apply the image sniffing rules, then the user agent must use the resource's Content-Type metadata to determine the type of the resource. If there is no type metadata, but the external resource link type has a default type defined, then the user agent must assume that the resource is of that type.
The stylesheet link type defines
rules for processing the resource's Content-Type metadata.
Once the user agent has established the type of the resource, the user agent must apply the resource if it is of a supported type and the other relevant conditions apply, and must ignore the resource otherwise.
If a document contains style sheet links labeled as follows:
<link rel="stylesheet" href="A" type="text/plain"> <link rel="stylesheet" href="B" type="text/css"> <link rel="stylesheet" href="C">
...then a compliant UA that supported only CSS style sheets
would fetch the B and C files, and skip the A file (since
text/plain is not the MIME type for CSS style
sheets).
For files B and C, it would then check the actual types returned
by the server. For those that are sent as text/css, it
would apply the styles, but for those labeled as
text/plain, or any other type, it would not.
If one the two files was returned without a
Content-Type metadata, or with a syntactically
incorrect type like Content-Type: "null", then the default type
for stylesheet links would kick
in. Since that default type is text/css, the
style sheet would nonetheless be applied.
The title
attribute gives the title of the link. With one exception, it is
purely advisory. The value is text. The exception is for style sheet
links, where the title
attribute defines alternative style sheet sets.
The title
attribute on link elements differs from the global
title attribute of most other
elements in that a link without a title does not inherit the title
of the parent element: it merely has no title.
The sizes attribute is used
with the icon link type. The attribute
must not be specified on link elements that do not have
a rel attribute that specifies
the icon keyword.
Some versions of HTTP defined a Link:
header, to be processed like a series of link elements.
If supported, for the purposes of ordering links defined by HTTP
headers must be assumed to come before any links in the document, in
the order that they were given in the HTTP entity header. (URIs in
these headers are to be processed and resolved according to the
rules given in HTTP; the rules of this specification don't
apply.) [HTTP] [RFC2068]
The DOM attributes href, rel, media, hreflang, and type, and sizes each must
reflect the respective content attributes of the same
name.
The DOM attribute relList must reflect the rel content attribute.
The DOM attribute disabled only applies
to style sheet links. When the link element defines a
style sheet link, then the disabled attribute behaves as
defined for the alternative
style sheets DOM. For all other link elements it
always return false and does nothing on setting.
meta elementitemprop attribute is present: flow content.itemprop attribute is present: phrasing content.charset attribute is present, or if the element is in the Encoding declaration state: in a head element.http-equiv attribute is present, and the element is not in the Encoding declaration state: in a head element.http-equiv attribute is present, and the element is not in the Encoding declaration state: in a noscript element that is a child of a head element.name attribute is present: where metadata content is expected.itemprop attribute is present: where phrasing content is expected.namehttp-equivcontentcharsetinterface HTMLMetaElement : HTMLElement { attribute DOMString name; attribute DOMString httpEquiv; };
The meta element represents various
kinds of metadata that cannot be expressed using the
title, base, link,
style, and script elements.
The meta element can represent document-level
metadata with the name
attribute, pragma directives with the http-equiv attribute, and the
file's character encoding declaration when an HTML
document is serialized to string form (e.g. for transmission over
the network or for disk storage) with the charset attribute.
Exactly one of the name,
http-equiv, charset, and itemprop attributes must be
specified.
If either name, http-equiv, or itemprop is specified, then the content attribute must also be
specified. Otherwise, it must be omitted.
The charset
attribute specifies the character encoding used by the
document. This is a character encoding declaration. If
the attribute is present in an XML
document, its value must be an ASCII
case-insensitive match for the string "UTF-8" (and the document is therefore required to
use UTF-8 as its encoding).
The charset
attribute on the meta element has no effect in XML
documents, and is only allowed in order to facilitate migration to
and from XHTML.
There must not be more than one meta element with a
charset attribute per
document.
The content
attribute gives the value of the document metadata or pragma
directive when the element is used for those purposes. The allowed
values depend on the exact context, as described in subsequent
sections of this specification.
If a meta element has a name attribute, it sets
document metadata. Document metadata is expressed in terms of
name/value pairs, the name
attribute on the meta element giving the name, and the
content attribute on the same
element giving the value. The name specifies what aspect of metadata
is being set; valid names and the meaning of their values are
described in the following sections. If a meta element
has no content attribute,
then the value part of the metadata name/value pair is the empty
string.
The name DOM
attribute must reflect the content attribute of the
same name. The DOM attribute httpEquiv must
reflect the content attribute http-equiv.
This specification defines a few names for the name attribute of the
meta element.
The value must be a short free-form string that giving the
name of the Web application that the page represents. If the page
is not a Web application, the application-name metadata name
must not be used. User agents may use the
application name in UI in preference to the page's
title, since the title might include status messages
and the like relevant to the status of the page at a particular
moment in time instead of just being the name of the
application.
The value must be a free-form string that describes the page. The value must be appropriate for use in a directory of pages, e.g. in a search engine.
The value must be a free-form string that identifies the software used to generate the document. This value must not be used on hand-authored pages.
Extensions to the predefined set of metadata names may be registered in the WHATWG Wiki MetaExtensions page.
Anyone is free to edit the WHATWG Wiki MetaExtensions page at any time to add a type. These new names must be specified with the following information:
The actual name being defined. The name should not be confusingly similar to any other defined name (e.g. differing only in case).
A short description of what the metadata name's meaning is, including the format the value is required to be in.
A list of other names that have exactly the same processing requirements. Authors should not use the names defined to be synonyms, they are only intended to allow user agents to support legacy content.
One of the following:
If a metadata name is added with the "proposal" status and found to be redundant with existing values, it should be removed and listed as a synonym for the existing value.
Conformance checkers must use the information given on the WHATWG Wiki MetaExtensions page to establish if a value not explicitly defined in this specification is allowed or not. When an author uses a new type not defined by either this specification or the Wiki page, conformance checkers should offer to add the value to the Wiki, with the details described above, with the "proposal" status.
This specification does not define how new values will get approved. It is expected that the Wiki will have a community that addresses this.
Metadata names whose values are to be URLs must not be proposed or accepted. Links must
be represented using the link element, not the
meta element.
When the http-equiv attribute
is specified on a meta element, the element is a pragma
directive.
The http-equiv
attribute is an enumerated attribute. The following
table lists the keywords defined for this attribute. The states
given in the first cell of the rows with keywords give the states to
which those keywords map. Some of the keywords
are non-conforming, as noted in the last column.
| State | Keywords | Notes |
|---|---|---|
| Content Language | content-language
| Non-conforming |
| Encoding declaration | content-type
| |
| Default style | default-style
| |
| Refresh | refresh
|
When a meta element is inserted into the document, if its
http-equiv attribute is
present and represents one of the above states, then the user agent
must run the algorithm appropriate for that state, as described in
the following list:
This non-conforming pragma sets the document-wide default language. Until the pragma is successfully processed, there is no document-wide default language.
If another meta element in the Content Language
state has already been successfully processed (i.e. when
it was inserted the user agent processed it and reached the last
step of this list of steps), then abort these steps.
If the meta element has no content attribute, or if that
attribute's value is the empty string, then abort these
steps.
Let input be the value of the
element's content
attribute.
Let position point at the first character of input.
Skip whitespace.
Collect a sequence of characters that are neither space characters nor a U+002C COMMA character (",").
Let the document-wide default language be the string that resulted from the previous step.
For meta elements in the Content Language
state, the content
attribute must have a value consisting of a valid RFC 3066
language code. [RFC3066]
This pragma is not exactly equivalent to the HTTP
Content-Language header, for instance it only
supports one language. [HTTP]
The Encoding
declaration state is just an alternative form of setting
the charset attribute: it is a
character encoding declaration. This state's user agent requirements are all handled
by the parsing section of the specification.
For meta elements in the Encoding declaration
state, the content
attribute must have a value that is an ASCII
case-insensitive match for a string that consists of: the
literal string "text/html;", optionally
followed by any number of space
characters, followed by the literal string "charset=", followed by the character encoding name
of the character encoding declaration.
If the document contains a meta element in the
Encoding
declaration state, then the document must not contain a
meta element with the charset attribute present.
The Encoding declaration state may be used in HTML documents, but elements in that state must not be used in XML documents.
This pragma sets the name of the default alternative style sheet set.
If the meta element has no content attribute, or if that
attribute's value is the empty string, then abort these
steps.
Set the preferred style sheet set to the
value of the element's content attribute. [CSSOM]
This pragma acts as timed redirect.
If another meta element in the Refresh state has
already been successfully processed (i.e. when it was inserted
the user agent processed it and reached the last step of this
list of steps), then abort these steps.
If the meta element has no content attribute, or if that
attribute's value is the empty string, then abort these
steps.
Let input be the value of the
element's content
attribute.
Let position point at the first character of input.
Skip whitespace.
Collect a sequence of characters in the range U+0030 DIGIT ZERO to U+0039 DIGIT NINE, and parse the resulting string using the rules for parsing non-negative integers. If the sequence of characters collected is the empty string, then no number will have been parsed; abort these steps. Otherwise, let time be the parsed number.
Collect a
sequence of characters in the range U+0030 DIGIT ZERO to
U+0039 DIGIT NINE and U+002E FULL STOP ("."). Ignore any collected characters.
Skip whitespace.
Let url be the address of the current page.
If the character in input pointed to
by position is a U+003B SEMICOLON (";"), then advance position to
the next character. Otherwise, jump to the last step.
Skip whitespace.
If the character in input pointed to by position is one of U+0055 LATIN CAPITAL LETTER U or U+0075 LATIN SMALL LETTER U, then advance position to the next character. Otherwise, jump to the last step.
If the character in input pointed to by position is one of U+0052 LATIN CAPITAL LETTER R or U+0072 LATIN SMALL LETTER R, then advance position to the next character. Otherwise, jump to the last step.
If the character in input pointed to by position is one of U+004C LATIN CAPITAL LETTER L or U+006C LATIN SMALL LETTER L, then advance position to the next character. Otherwise, jump to the last step.
Skip whitespace.
If the character in input pointed to
by position is a U+003D EQUALS SIGN ("="), then advance position to
the next character. Otherwise, jump to the last step.
Skip whitespace.
If the character in input pointed to by position is either a U+0027 APOSTROPHE character (') or U+0022 QUOTATION MARK character ("), then let quote be that character, and advance position to the next character. Otherwise, let quote be the empty string.
Let url be equal to the substring of input from the character at position to the end of the string.
If quote is not the empty string, and there is a character in url equal to quote, then truncate url at that character, so that it and all subsequent characters are removed.
Strip any trailing space characters from the end of url.
Strip any U+0009 CHARACTER TABULATION, U+000A LINE FEED (LF), and U+000D CARRIAGE RETURN (CR) characters from url.
Resolve the url value to an absolute URL,
relative to the meta element. If this fails, abort
these steps.
Perform one or more of the following steps:
Set a timer so that in time seconds, adjusted to take into account user or user agent preferences, if the user has not canceled the redirect, the user agent navigates the document's browsing context to url, with replacement enabled, and with the document's browsing context as the source browsing context.
Provide the user with an interface that, when selected, navigates a browsing context to url, with the document's browsing context as the source browsing context.
Do nothing.
In addition, the user agent may, as with anything, inform the user of any and all aspects of its operation, including the state of any timers, the destinations of any timed redirects, and so forth.
For meta elements in the Refresh state, the
content attribute must have
a value consisting either of:
;), followed by one or
more space characters,
followed by either a U+0055 LATIN CAPITAL LETTER U or a U+0075
LATIN SMALL LETTER U, a U+0052 LATIN CAPITAL LETTER R or a U+0072
LATIN SMALL LETTER R, a U+004C LATIN CAPITAL LETTER L or a U+006C
LATIN SMALL LETTER L, a U+003D EQUALS SIGN (=), and then a valid URL.In the former case, the integer represents a number of seconds before the page is to be reloaded; in the latter case the integer represents a number of seconds before the page is to be replaced by the page at the given URL.
There must not be more than one meta element with
any particular state in the document at a time.
Extensions to the predefined set of pragma directives may, under certain conditions, be registered in the WHATWG Wiki PragmaExtensions page.
Such extensions must use a name that is identical to a previously-registered HTTP header defined in an RFC, and must have behavior identical to that described for the HTTP header. Pragma directions corresponding to headers describing metadata, or not requiring specific user agent processing, must not be registered; instead, use metadata names. Pragma directions corresponding to headers that affect the HTTP processing model (e.g. caching) must not be registered, as they would result in HTTP-level behavior being different for user agents that implement HTML than for user agents that do not.
Anyone is free to edit the WHATWG Wiki PragmaExtensions page at any time to add a pragma directive satisfying these conditions. Such registrations must specify the following information:
The actual name being defined.
A short description of the purpose of the pragma directive.
Conformance checkers must use the information given on the WHATWG Wiki PragmaExtensions page to establish if a value not explicitly defined in this specification is allowed or not.
A character encoding declaration is a mechanism by which the character encoding used to store or transmit a document is specified.
The following restrictions apply to character encoding declarations:
If an HTML document does not
start with a BOM, and if its encoding is not explicitly given by
Content-Type metadata, then the
character encoding used must be an ASCII-compatible character
encoding, and, in addition, if that encoding isn't US-ASCII
itself, then the encoding must be specified using a
meta element with a charset attribute or a
meta element in the Encoding declaration
state.
If an HTML document contains
a meta element with a charset attribute or a
meta element in the Encoding declaration
state, then the character encoding used must be an
ASCII-compatible character encoding.
Authors should not use JIS-X-0208 (JIS_C6226-1983), JIS-X-0212 (JIS_X0212-1990), encodings based on ISO-2022, and encodings based on EBCDIC. Authors should not use UTF-32. Authors must not use the CESU-8, UTF-7, BOCU-1 and SCSU encodings. [RFC1345] [RFC1468] [RFC2237] [RFC1554] [RFC1922] [RFC1557] [UTF32] [CESU8] [UTF7] [BOCU1] [SCSU]
Authors are encouraged to use UTF-8. Conformance checkers may advise against authors using legacy encodings.
Authoring tools should default to using UTF-8 for newly-created documents.
In XHTML, the XML declaration should be used for inline character encoding information, if necessary.
style elementscoped attribute is present: flow content.scoped attribute is absent: where metadata content is expected.scoped attribute is absent: in a noscript element that is a child of a head element.scoped attribute is present: where flow content is expected, but before any other flow content other than other style elements and inter-element whitespace.type attribute.mediatypescopedtitle attribute has special semantics on this element.interface HTMLStyleElement : HTMLElement { attribute boolean disabled; attribute DOMString media; attribute DOMString type; attribute boolean scoped; };
The LinkStyle interface must also be implemented
by this element, the styling processing model defines
how. [CSSOM]
The style element allows authors to embed style
information in their documents. The style element is
one of several inputs to the styling processing
model. The element does not represent content for the user.
If the type
attribute is given, it must contain a valid MIME type, optionally
with parameters, that designates a styling language. [RFC2046] If the attribute is absent, the
type defaults to text/css. [RFC2138]
When examining types to determine if they support the language, user agents must not ignore unknown MIME parameters — types with unknown parameters must be assumed to be unsupported.
The media
attribute says which media the styles apply to. The value must be a
valid media query. [MQ]
User agents must apply the styles to views while their state match the listed media,
and must not apply them otherwise.
The styles might be further limited in scope,
e.g. in CSS with the use of @media
blocks. This specification does not override such further
restrictions or requirements.
The default, if the media attribute is omitted, is
all, meaning that by default styles apply to all
media.
The scoped
attribute is a boolean attribute. If set, it indicates
that the styles are intended just for the subtree rooted at the
style element's parent element, as opposed to the whole
Document.
If the scoped attribute is
present, then the user agent must apply the specified style
information only to the style element's parent element
(if any), and that element's child nodes. Otherwise, the specified
styles must, if applied, be applied to the entire document.
The title attribute on
style elements defines alternative style sheet
sets. If the style element has no title attribute, then it has no
title; the title attribute of
ancestors does not apply to the style element. [CSSOM]
The title
attribute on style elements, like the title attribute on link
elements, differs from the global title attribute in that a
style block without a title does not inherit the title
of the parent element: it merely has no title.
All descendant elements must be processed, according to their
semantics, before the style element itself is
evaluated. For styling languages that consist of pure text, user
agents must evaluate style elements by passing the
concatenation of the contents of all the text nodes that are direct children of the
style element (not any other nodes such as comments or
elements), in tree order, to the style system. For
XML-based styling languages, user agents must pass all the child
nodes of the style element to the style system.
All URLs found by the styling language's processor must be resolved, relative to the element (or as defined by the styling language), when the processor is invoked.
Once the element has been evaluated, if it had no subresources or
once all the subresources it uses have been fetched, the user agent must queue a
task to fire a simple event called load at the style element. If
the resource has a subresource that fails to completely load for any
reason (e.g. DNS error, HTTP 404 response, the connection being
prematurely closed, unsupported Content-Type), the user agent must
instead queue a task to fire a simple
event called error at the
style element. Non-network errors in the processing of
the element's contents or its subresources (e.g. CSS parse errors)
are not failures for the purposes of this paragraph. The
style element must delay the load event of
the element's document until one of these tasks has been queued.
The task source for these tasks is the DOM manipulation task source.
This specification does not specify a style system, but CSS is expected to be supported by most Web browsers. [CSS]
The media, type and scoped DOM attributes
must reflect the respective content attributes of the
same name.
The DOM disabled attribute
behaves as defined for the
alternative style sheets DOM.
The link and style elements can provide
styling information for the user agent to use when rendering the
document. The DOM Styling specification specifies what styling
information is to be used by the user agent and how it is to be
used. [CSSOM]
The style and link elements implement
the LinkStyle interface. [CSSOM]
For style elements, if the user agent does not
support the specified styling language, then the sheet attribute of the element's
LinkStyle interface must return null. Similarly,
link elements that do not represent external resource links that contribute to
the styling processing model (i.e. that do not have a stylesheet keyword in their rel attribute), and link
elements whose specified resource has not yet been fetched, or is
not in a supported styling language, must have their
LinkStyle interface's sheet attribute return null.
Otherwise, the LinkStyle interface's sheet attribute must return a
StyleSheet object with the attributes implemented as
follows: [CSSOM]
type DOM attribute)The content type must be the same as the style's specified
type. For style elements, this is the same as the
type content attribute's
value, or text/css if that is omitted. For
link elements, this is the Content-Type metadata of the specified
resource.
href DOM attribute)For link elements, the location must be the
result of resolving the
URL given by the element's href content attribute, relative to
the element, or the empty string if that fails. For
style elements, there is no location.
media DOM attribute)The media must be the same as the value of the element's
media content attribute.
title DOM attribute)The title must be the same as the value of the element's
title content attribute, if the
attribute is present and has a non-empty value. If the attribute is
absent or its value is the empty string, then the style sheet does
not have a title. The title is used for defining alternative
style sheet sets.
The disabled DOM
attribute on link and style elements must
return false and do nothing on setting, if the sheet attribute of their
LinkStyle interface is null. Otherwise, it must return
the value of the StyleSheet interface's disabled attribute on
getting, and forward the new value to that same attribute on
setting.
The rules for handling alternative style sheets are defined in the CSS object model specification. [CSSOM]
Scripts allow authors to add interactivity to their documents.
Authors are encouraged to use declarative alternatives to scripting where possible, as declarative mechanisms are often more maintainable, and many users disable scripting.
For example, instead of using script to show or hide a section
to show more details, the details element could be
used.
Authors are also encouraged to make their applications degrade gracefully in the absence of scripting support.
For example, if an author provides a link in a table header to dynamically resort the table, the link could also be made to function without scripts by requesting the sorted table from the server.
script elementsrc
attribute, depends on the value of the type attribute.src
attribute, the element must be either empty or contain only
script documentation.srcasyncdefertypecharsetinterface HTMLScriptElement : HTMLElement { attribute DOMString src; attribute boolean async; attribute boolean defer; attribute DOMString type; attribute DOMString charset; attribute DOMString text; };
The script element allows authors to include dynamic
script and data blocks in their documents. The element does not
represent content for the user.
When used to include dynamic scripts, the scripts may either be
embedded inline or may be imported from an external file using the
src attribute. If the language
is not that described by "text/javascript",
then the type attribute must
be present. If the type
attribute is present, its value must be the type of the script's
language.
When used to include data blocks, the data must be embedded
inline, the format of the data must be given using the type attribute, and the src attribute must not be
specified.
The type
attribute gives the language of the script or format of the data. If
the attribute is present, its value must be a valid MIME type,
optionally with parameters. The charset
parameter must not be specified. (The default, which is used if the
attribute is absent, is "text/javascript".) [RFC2046]
The src
attribute, if specified, gives the address of the external script
resource to use. The value of the attribute must be a valid
URL identifying a script resource of the type given by the
type attribute, if the
attribute is present, or of the type "text/javascript", if the attribute is absent.
The charset
attribute gives the character encoding of the external script
resource. The attribute must not be specified if the src attribute is not present. If the
attribute is set, its value must be a valid character encoding name,
must be the preferred name for that encoding, and must match the
encoding given in the charset parameter of the
Content-Type metadata of the
external file, if any. [IANACHARSET]
The async and
defer attributes
are boolean attributes that
indicate how the script should be executed.
There are three possible modes that can be selected using these
attributes. If the async
attribute is present, then the script will be executed
asynchronously, as soon as it is available. If the async attribute is not present but
the defer attribute is
present, then the script is executed when the page has finished
parsing. If neither attribute is present, then the script is
fetched and executed immediately, before the user agent continues
parsing the page. The exact processing details for these attributes
is described below.
The defer attribute may be
specified even if the async
attribute is specified, to cause legacy Web browsers that only
support defer (and not async) to fall back to the defer behavior instead of the
synchronous blocking behavior that is the default.
Changing the src, type, charset, async, and defer attributes dynamically has no
direct effect; these attribute are only used at specific times
described below (namely, when the element is inserted into the document).
script elements have four associated pieces of
metadata. The first is a flag indicating whether or not the script
block has been "already executed". Initially,
script elements must have this flag unset (script
blocks, when created, are not "already executed"). When a
script element is cloned, the "already executed" flag,
if set, must be propagated to the clone when it is created. The
second is a flag indicating whether the element was
"parser-inserted". This flag is set by the HTML
parser and is used to handle document.write() calls. The third
and fourth pieces of metadata are the script block's
type and the script block's character
encoding. They are determined when the script is run,
based on the attributes on the element at that time.
When a script element that is neither marked as
having "already executed" nor marked as being
"parser-inserted" experiences one of the events listed
in the following list, the user agent must run the script element:
script element gets inserted into a document.script element's child nodes are changed.script element has a src attribute set where previously
the element had no such attribute.Running a script: When a
script element is to be run, the user agent must act as
follows:
If either:
script element has a type attribute and its value is
the empty string, orscript element has no type attribute but it has a language attribute and
that attribute's value is the empty string, orscript element has neither a type attribute nor a language attribute, then...let the script block's type for this
script element be "text/javascript".
Otherwise, if the script element has a type attribute, let the
script block's type for this script element be
the value of that attribute.
Otherwise, the element has a non-empty language attribute; let
the script block's type for this script
element be the concatenation of the string "text/" followed by the value of the language attribute.
The language attribute is never
conforming, and is always ignored if there is a type attribute present.
If the script element has a charset attribute, then let
the script block's character encoding for this
script element be the encoding given by the charset attribute.
Otherwise, let the script block's character encoding
for this script element be the same as the encoding of the document
itself.
If scripting is
disabled for the script element, or if the
user agent does not support the scripting language
given by the script block's type for this
script element, then the user agent must abort these
steps at this point. The script is not executed.
If the element has no src
attribute, and its child nodes consist only of comment nodes and
empty text nodes, then the user
agent must abort these steps at this point. The script is not
executed.
The user agent must set the element's "already executed" flag.
If the element has a src
attribute, then the value of that attribute must be resolved relative to the element, and
if that is successful, the specified resource must then be fetched.
For historical reasons, if the URL is a javascript:
URL, then the user agent must not, despite the requirements
in the definition of the fetching
algorithm, actually execute the given script; instead the user
agent must act as if it had received an empty HTTP 400
response.
Once the resource's Content Type metadata is available, if it ever is, apply the algorithm for extracting an encoding from a Content-Type to it. If this returns an encoding, and the user agent supports that encoding, then let the script block's character encoding be that encoding.
Once the fetching process has completed, and the script has completed loading, the user agent will have to complete the steps described below. (If the parser is still active at that time, those steps defer to the parser to handle the execution of pending scripts.)
For performance reasons, user agents may start fetching the
script as soon as the attribute is set, instead, in the hope that
the element will be inserted into the document. Either way, once
the element is inserted into the document, the load must have
started. If the UA performs such prefetching, but the element is
never inserted in the document, or the src attribute is dynamically
changed, then the
user agent will not execute the script, and the fetching process
will have been effectively wasted.
Then, the first of the following options that describes the situation must be followed:
defer attribute, and the
element does not have an async attributeasync attribute and a src attributeasync attribute but no src attribute, and the list
of scripts that will execute asynchronously is not
emptysrc
attribute and has been flagged as
"parser-inserted"src
attributeFetching an external script must delay the load event of the element's document until the task that is queued by the networking task source once the resource has been fetched (defined below) has been run.
When a script completes loading: If the
script element was added to one of the lists mentioned
above and the document is still being parsed, then the parser
handles it. Otherwise, the UA must run the following steps as the
task that the networking
task source places on the task queue:
script element was added to the list
of scripts that will execute when the document has finished
parsing:If the script element is not the first element
in the list, then do nothing yet. Stop going through these
steps.
Otherwise, execute the script block (the first element in the list).
Remove the script element from the list
(i.e. shift out the first entry in the list).
If there are any more entries in the list, and if the script associated with the element that is now the first in the list is already loaded, then jump back to step 2 to execute it.
script element was added to the list
of scripts that will execute asynchronously:If the script is not the first element in the list, then do nothing yet. Stop going through these steps.
Execute the script block (the first element in the list).
Remove the script element from the list
(i.e. shift out the first entry in the list).
If there are any more scripts in the list, and the element
now at the head of the list had no src attribute when it was added
to the list, or had one, but its associated script has finished
loading, then jump back to step 2 to execute the script
associated with this element.
script element was added to the list
of scripts that will execute as soon as possible:Execute the script block.
Remove the script element from the list.
Executing a script block: When the steps above require that the script block be executed, the user agent must act as follows:
Executing the script block must just consist of firing a simple event called
error at the element.
Initialize the script block's source as follows:
The contents of that file, interpreted as string of Unicode characters, are the script source.
For each of the rows in the following table, starting with the first one and going down, if the file has as many or more bytes available than the number of bytes in the first column, and the first bytes of the file match the bytes given in the first column, then set the script block's character encoding to the encoding given in the cell in the second column of that row, irrespective of any previous value:
| Bytes in Hexadecimal | Encoding |
|---|---|
| FE FF | UTF-16BE |
| FF FE | UTF-16LE |
| EF BB BF | UTF-8 |
This step looks for Unicode Byte Order Marks (BOMs).
The file must then be converted to Unicode using the character encoding given by the script block's character encoding.
The value of the DOM text attribute at the time the
"running a script" algorithm was first invoked is
the script source.
The child nodes of the script element at the
time the "running a script" algorithm was first
invoked are the script source.
Create a
script from the script element node, using
the the script block's source and the the script
block's type.
This is where the script is compiled and actually executed.
Fire a simple event called load at the script
element.
The DOM attributes src, type, charset, async, and defer, each must
reflect the respective content attributes of the same
name.
text [ = value ]Returns the contents of the element, ignoring child nodes that aren't text nodes.
Can be set, to replace the element's children with the given value.
The DOM attribute text must return a
concatenation of the contents of all the text nodes that are direct children of the
script element (ignoring any other nodes such as
comments or elements), in tree order. On setting, it must act the
same way as the textContent DOM attribute.
In this example, two script elements are used. One
embeds an external script, and the other includes some data.
<script src="game-engine.js"></script> <script type="text/x-game-map"> ........U.........e o............A....e .....A.....AAA....e .A..AAA...AAAAA...e </script>
The data in this case might be used by the script to generate the map of a video game. The data doesn't have to be used that way, though; maybe the map data is actually embedded in other parts of the page's markup, and the data block here is just used by the site's search engine to help users who are looking for particular features in their game maps.
When inserted using the document.write() method,
script elements execute (typically synchronously), but
when inserted using innerHTML and outerHTML attributes, they do not
execute at all.
A user agent is said to support the scripting language if the script block's type matches the MIME type of a scripting language that the user agent implements.
The following lists some MIME types and the languages to which they refer:
application/ecmascriptapplication/javascriptapplication/x-ecmascriptapplication/x-javascripttext/ecmascripttext/javascripttext/javascript1.0text/javascript1.1text/javascript1.2text/javascript1.3text/javascript1.4text/javascript1.5text/jscripttext/livescripttext/x-ecmascripttext/x-javascripttext/javascript;e4x=1User agents may support other MIME types and other languages.
When examining types to determine if they support the language, user agents must not ignore unknown MIME parameters — types with unknown parameters must be assumed to be unsupported.
If a script element's src attribute is specified, then the
contents of the script element, if any, must be such
that the value of the DOM text
attribute, which is derived from the element's contents, matches the
documentation production in the following
ABNF, the character set for which is Unicode. [ABNF]
documentation = *( *( space / tab / comment ) [ line-comment ] newline )
comment = slash star *( not-star / star not-slash ) 1*star slash
line-comment = slash slash *not-newline
; characters
tab = %x0009 ; U+0009 TAB
newline = %x000A ; U+000A LINE FEED
space = %x0020 ; U+0020 SPACE
star = %x002A ; U+002A ASTERISK
slash = %x002F ; U+002F SOLIDUS
not-newline = %x0000-0009 / %x000B-%10FFFF
; a Unicode character other than U+000A LINE FEED
not-star = %x0000-0029 / %x002B-%10FFFF
; a Unicode character other than U+002A ASTERISK
not-slash = %x0000-002E / %x0030-%10FFFF
; a Unicode character other than U+002F SOLIDUS
This allows authors to include documentation, such as license
information or API information, inside their documents while still
referring to external script files. The syntax is constrained so
that authors don't accidentally include what looks like valid
script while also providing a src attribute.
<script src="cool-effects.js"> // create new instances using: // var e = new Effect(); // start the effect using .play, stop using .stop: // e.play(); // e.stop(); </script>
noscript elementhead element of an HTML document, if there are no ancestor noscript elements.noscript elements.head element: in any order, zero or more link elements, zero or more style elements, and zero or more meta elements.head element: transparent, but there must be no noscript element descendants.HTMLElement.The noscript element represents nothing
if scripting is enabled, and
represents its children if scripting is disabled. It is used
to present different markup to user agents that support scripting
and those that don't support scripting, by affecting how the
document is parsed.
When used in HTML documents, the allowed content model is as follows:
head element, if scripting is disabled for the
noscript elementThe noscript element must contain only
link, style, and meta
elements.
head element, if scripting is enabled for the
noscript elementThe noscript element must contain only text,
except that invoking the HTML fragment parsing
algorithm with the noscript element as the context element and the text contents as the input must result in a list of nodes that consists
only of link, style, and
meta elements, and no parse
errors.
head elements, if scripting is disabled for the
noscript elementThe noscript element's content model is
transparent, with the additional restriction that a
noscript element must not have a noscript
element as an ancestor (that is, noscript can't be
nested).
head elements, if scripting is enabled for the
noscript elementThe noscript element must contain only text,
except that the text must be such that running the following
algorithm results in a conforming document with no
noscript elements and no script
elements, and such that no step in the algorithm causes an
HTML parser to flag a parse error:
script element from the
document.noscript element in the
document. For every noscript element in that list,
perform the following steps:
noscript element.noscript element, and call these
elements the before children.noscript element, and
call these elements the after children.noscript
element.innerHTML
attribute of the parent element to the value
of s. (This, as a side-effect, causes the
noscript element to be removed from the
document.)All these contortions are required because, for
historical reasons, the noscript element is handled
differently by the HTML parser based on whether scripting was enabled or not when the
parser was invoked. The element is not allowed in XML, because in
XML the parser is not affected by such state, and thus the element
would not have the desired effect.
The noscript element must not be used in XML
documents.
The noscript element is only
effective in the the HTML syntax, it has no effect in
the the XHTML syntax.
The noscript element has no other requirements. In
particular, children of the noscript element are not
exempt from form submission, scripting, and so forth,
even when scripting is enabled
for the element.
Some elements, for example
address elements, are scoped to their nearest ancestor
sectioning content. For such elements x, the elements that apply to a sectioning
content element e are all the x elements whose nearest sectioning
content ancestor is e.
body elementhtml element.onafterprintonbeforeprintonbeforeunloadonbluronerroronfocusonhashchangeonloadonmessageonofflineononlineonpopstateonredoonresizeonstorageonundoonunloadinterface HTMLBodyElement : HTMLElement { attribute Function onafterprint; attribute Function onbeforeprint; attribute Function onbeforeunload; attribute Function onblur; attribute Function onerror; attribute Function onfocus; attribute Function onhashchange; attribute Function onload; attribute Function onmessage; attribute Function onoffline; attribute Function ononline; attribute Function onpopstate; attribute Function onredo; attribute Function onresize; attribute Function onstorage; attribute Function onundo; attribute Function onunload; };
The body element represents the main
content of the document.
In conforming documents, there is only one body
element. The document.body
DOM attribute provides scripts with easy access to a document's
body element.
Some DOM operations (for example, parts of the
drag and drop model) are defined in terms of "the
body element". This refers to a particular element in the
DOM, as per the definition of the term, and not any arbitrary
body element.
The body element exposes as event handler
content attributes a number of the event handler
attributes of the Window object. It also mirrors
their event handler DOM attributes.
The onblur, onerror, onfocus, and onload event handler
attributes of the Window object, exposed on the
body element, shadow the generic event handler
attributes with the same names normally supported by
HTML elements.
Thus, for example, a bubbling error event fired on a child of the
body element of a Document would first trigger
the onerror event handler
content attributes of that element, then that of the root
html element, and only then would it trigger
the onerror event handler content
attribute on the body element. This is because
the event would bubble from the target, to the body, to
the html, to the Document, to the
Window, and the event handler attribute on the body
is watching the Window not the body. A
regular event listener attached to the body using addEventListener(), however, would fire when the
event bubbled through the body and not when it reaches
the Window object.
section elementformatBlock candidate.citeinterface HTMLSectionElement : HTMLElement { attribute DOMString cite; };
The section element represents a
generic document or application section. A section, in this context,
is a thematic grouping of content, typically with a heading, possibly
with a footer.
Examples of sections would be chapters, the various tabbed pages in a tabbed dialog box, or the numbered sections of a thesis. A Web site's home page could be split into sections for an introduction, news items, contact information.
The cite
attribute may be used if the content of the section was taken from
another page (e.g. syndicating content from multiple sources on one
page). The attribute, if present, must contain a valid
URL referencing the original source. To
obtain the corresponding citation link, the value of the attribute
must be resolved relative to the
element. User agents should allow users to follow such citation
links.
The cite DOM
attribute must reflect the element's cite content attribute.
The section element is not a generic
container element. When an element is needed for styling purposes or
as a convenience for scripting, authors are encouraged to use the
div element instead. A general rule is that the
section element is appropriate only if the element's
contents would be listed explicitly in the document's
outline.
In the following example, we see an article (part of a larger Web page) about apples, containing two short sections.
<article> <hgroup> <h1>Apples</h1> <h2>Tasty, delicious fruit!</h2> </hgroup> <p>The apple is the pomaceous fruit of the apple tree.</p> <section> <h1>Red Delicious</h1> <p>These bright red apples are the most common found in many supermarkets.</p> </section> <section> <h1>Granny Smith</h1> <p>These juicy, green apples make a great filling for apple pies.</p> </section> </article>
Notice how the use of section means that the author
can use h1 elements throughout, without having to
worry about whether a particular section is at the top level, the
second level, the third level, and so on.
nav elementformatBlock candidate.HTMLElement.The nav element represents a section of
a page that links to other pages or to parts within the page: a
section with navigation links. Not all groups of links on a page
need to be in a nav element — only sections that
consist of primary navigation blocks are appropriate for the
nav element. In particular, it is common for footers to
have a list of links to various key parts of a site, but the
footer element is more appropriate in such cases.
In the following example, the page has several places where links are present, but only one of those places is considered a navigation section.
<body>
<header>
<h1>Wake up sheeple!</h1>
<p><a href="news.html">News</a> -
<a href="blog.html">Blog</a> -
<a href="forums.html">Forums</a></p>
<p>Last Modified: <time>2009-04-01</time></p>
<nav>
<h1>Navigation</h1>
<ul>
<li><a href="articles.html">Index of all articles</a></li>
<li><a href="today.html">Things sheeple need to wake up for today</a></li>
<li><a href="successes.html">Sheeple we have managed to wake</a></li>
</ul>
</nav>
</header>
<article>
<p>...page content would be here...</p>
</article>
<footer>
<p>Copyright © 2006 The Example Company</p>
<p><a href="about.html">About</a> -
<a href="policy.html">Privacy Policy</a> -
<a href="contact.html">Contact Us</a></p>
</footer>
</body>
article elementformatBlock candidate.citepubdateinterface HTMLArticleElement : HTMLElement { attribute DOMString cite; attribute DOMString pubDate; };
The article element represents a
section of a page that consists of a composition that forms an
independent part of a document, page, or site. This could be a forum
post, a magazine or newspaper article, a Web log entry, a
user-submitted comment, or any other independent item of
content.
An article element is "independent" in
that its contents could stand alone, for example in syndication.
However, the element is still associated with its ancestors; for
instance, contact information that applies to a parent body
element still covers the article as well.
When article elements are nested, the inner
article elements represent articles that are in
principle related to the contents of the outer article. For
instance, a Web log entry on a site that accepts user-submitted
comments could represent the comments as article
elements nested within the article element for the Web
log entry.
Author information associated with an article
element (q.v. the address element) does not apply to
nested article elements.
The cite
attribute may be used if the content of the article was taken from
another page (e.g. syndicating content from multiple sources on one
page). The attribute, if present, must contain a valid
URL referencing the original source. To
obtain the corresponding citation link, the value of the attribute
must be resolved relative to the
element. User agents should allow users to follow such citation
links.
The pubdate
attribute may be used to specify the time and date that the article
was first published. If present, the pubdate attribute must be a
valid global date and time string value.
The cite DOM
attribute must reflect the element's cite content attribute. The pubDate DOM attribute
must reflect the element's pubdate content attribute.
aside elementformatBlock candidate.HTMLElement.The aside element represents a section
of a page that consists of content that is tangentially related to
the content around the aside element, and which could
be considered separate from that content. Such sections are often
represented as sidebars in printed typography.
The element can also be used for typographical effects like pull quotes.
It's not appropriate to use the aside
element just for parentheticals, since those are part of the main
flow of the document.
The following example shows how an aside is used to mark up background material on Switzerland in a much longer news story on Europe.
<aside> <h1>Switzerland</h1> <p>Switzerland, a land-locked country in the middle of geographic Europe, has not joined the geopolitical European Union, though it is a signatory to a number of European treaties.</p> </aside>
The following example shows how an aside is used to mark up a pull quote in a longer article.
... <p>He later joined a large company, continuing on the same work. <q>I love my job. People ask me what I do for fun when I'm not at work. But I'm paid to do my hobby, so I never know what to answer. Some people wonder what they would do if they didn't have to work... but I know what I would do, because I was unemployed for a year, and I filled that time doing exactly what I do now.</q></p> <aside> <q> People ask me what I do for fun when I'm not at work. But I'm paid to do my hobby, so I never know what to answer. </q> </aside> <p>Of course his work — or should that be hobby? — isn't his only passion. He also enjoys other pleasures.</p> ...
h1, h2,
h3, h4,
h5, and h6
elementsformatBlock candidate.interface HTMLHeadingElement : HTMLElement {};
These elements represent headings for their sections.
The semantics and meaning of these elements are defined in the section on headings and sections.
These elements have a rank given by the number in
their name. The h1 element is said to have the highest
rank, the h6 element has the lowest rank, and two
elements with the same name have equal rank.
hgroup elementformatBlock candidate.h1, h2, h3, h4, h5, and/or h6 elements.HTMLElement.The hgroup element represents the
heading of a section. The element is used to group a set of
h1–h6 elements when the heading has
multiple levels, such as subheadings, alternative titles, or
taglines.
For the purposes of document summaries, outlines, and the like,
the text of hgroup elements is defined to be the text
of