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Overview.src.html
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Overview.src.html
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<!doctype html>
<html lang="en-US">
<head>
<meta charset=UTF-8>
<title>DOM Standard</title>
<style>
@media print {
[data-anolis-spec]::after { content:"[" attr(data-anolis-spec) "]"; font-size:.6em; vertical-align:super; text-transform:uppercase }
}
</style>
<link rel=stylesheet href=//www.whatwg.org/style/specification>
<link rel=icon href=//resources.whatwg.org/logo-dom.svg>
</head>
<body>
<div class=head>
<p><a class=logo href=//www.whatwg.org/><img alt=WHATWG src=//resources.whatwg.org/logo-dom.svg width=100 height=100></a></p>
<h1>DOM</h1>
<h2 class="no-num no-toc">Living Standard — Last Updated [DATE: 01 Jan 1901]</h2>
<dl>
<dt>This Version:
<dd><a href="http://dom.spec.whatwg.org/">http://dom.spec.whatwg.org/</a>
<dt>Participate:</dt>
<dd class=dontpublish>Send feedback to
<a href="mailto:www-dom@w3.org?subject=%5Bdom%5D%20">www-dom@w3.org</a> (<a href="http://lists.w3.org/Archives/Public/www-dom/">archives</a>) or
<a href="https://www.w3.org/Bugs/Public/enter_bug.cgi?product=WebAppsWG&component=DOM">file a bug</a>
(<a href="https://www.w3.org/Bugs/Public/buglist.cgi?product=WebAppsWG&component=DOM&resolution=---">open bugs</a>)
<dd class=dontpublish><a href="http://wiki.whatwg.org/wiki/IRC">IRC: #whatwg on Freenode</a>
<dt>Version History:
<dd><a href=https://github.com/whatwg/dom/commits>https://github.com/whatwg/dom/commits</a>
<dd><a href="https://twitter.com/thedomstandard">@thedomstandard</a>
<dt>Editors:
<dd><a href="http://annevankesteren.nl/">Anne van Kesteren</a>
<<a href="mailto:annevk@annevk.nl">annevk@annevk.nl</a>>
<dd>Aryeh Gregor
(<a href="http://www.mozilla.org/">Mozilla Foundation</a>)
<<a href=mailto:ayg@aryeh.name>ayg@aryeh.name</a>>
<dd>Ms2ger (<a href="http://www.mozilla.org/">Mozilla Foundation</a>)
<<a href="mailto:ms2ger@gmail.com">ms2ger@gmail.com</a>>
</dl>
<script src=//resources.whatwg.org/file-bug.js async></script>
<p class=copyright><a rel="license" href="http://creativecommons.org/publicdomain/zero/1.0/"><img src="http://i.creativecommons.org/p/zero/1.0/80x15.png" alt="CC0"></a>
To the extent possible under law, the editors have waived all copyright and
related or neighboring rights to this work. In addition, as of
[DATE: 01 Jan 1901], the editors have made this specification available
under the
<a rel="license"
href="http://www.openwebfoundation.org/legal/the-owf-1-0-agreements/owfa-1-0">Open Web Foundation Agreement Version 1.0</a>,
which is available at
http://www.openwebfoundation.org/legal/the-owf-1-0-agreements/owfa-1-0.
</div>
<h2 class="no-num no-toc">Abstract</h2>
<p>DOM defines the event and document model the Web platform uses. The
DOM is a language- and platform neutral interface that allows programs and
scripts to dynamically access and update the content and structure of
documents.
<h2 class="no-num no-toc">Table of Contents</h2>
<!--toc-->
<h2 class=no-num>Goals</h2>
<p>This specification standardizes the DOM. It does so as follows:</p>
<ol>
<li>
<p>By consolidating <cite>DOM Level 3 Core</cite>
<span data-anolis-ref class=informative>DOM3CORE</span>,
<cite>Element Traversal</cite>
<span data-anolis-ref class=informative>ELEMENTTRAVERSAL</span>, the
"DOM Event Architecture" and "Basic Event Interfaces" chapters of
<cite>DOM Level 3 Events</cite>
<span data-anolis-ref class=informative>DOM3EVENTS</span> (specific type
of events do not belong in the base specification), and
<cite>DOM Level 2 Traversal and Range</cite>
<span data-anolis-ref class=informative>DOM2TR</span>, and:
<ul>
<li>Aligning them with the needs of ECMAScript where possible.
<li>Aligning them with existing implementations.
<li>Simplifying them as much as possible.
</ul>
<li><p>By moving features from HTML5 that ought to be part of the DOM
platform here, while preventing a dependency on HTML5.
<span data-anolis-ref class=informative>HTML</span>
<li>
<p>By defining a replacement for the "Mutation Events" and
"Mutation Name Event Types" chapters of <cite>DOM Level 3 Events</cite>
<span data-anolis-ref class=informative>DOM3EVENTS</span> as the old model
was problematic.
<p class=note>The old model is expected to be removed from implementations
in due course.
<li><p>By defining new features that simplify common DOM operations.
</ol>
<h2>Conformance</h2>
<p>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.
<p>The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in RFC 2119.
For readability, these words do not appear in all uppercase letters in this
specification. <span data-anolis-ref>RFC2119</span>
<p>Requirements phrased in the imperative as part of algorithms
(such as "strip any leading space characters" or "return false and
terminate these steps") are to be interpreted with the meaning of the
key word ("must", "should", "may", etc) used in introducing the
algorithm.
<p>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.)
<p id="hardwareLimitations">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.
<p>When a method or an attribute is said to call another method or attribute, the user agent must invoke its internal API for that attribute or method so that e.g. the author can't change the behavior by overriding attributes or methods with custom properties or functions in ECMAScript.
<p>Unless otherwise stated, string comparisons are done in a <span>case-sensitive</span> manner.
<h3>Dependencies</h3>
<p>The IDL fragments in this specification must be interpreted as
required for conforming IDL fragments, as described in the Web IDL
specification. <span data-anolis-ref>WEBIDL</span>
<p>Some of the terms used in this specification are defined in
<cite>Encoding</cite>, <cite>Web IDL</cite>, <cite>XML</cite>, and
<cite>Namespaces in XML</cite>.
<span data-anolis-ref>ENCODING</span>
<span data-anolis-ref>WEBIDL</span>
<span data-anolis-ref>XML</span>
<span data-anolis-ref>XMLNS</span>
<h3>Extensibility</h3>
<p>Vendor-specific proprietary extensions to this specification are
strongly discouraged. Authors 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.
<p>If vendor-specific 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 neither contradicts nor causes the
non-conformance of functionality defined in the specification.
<!-- thanks to QA Framework -->
<p>When vendor-neutral extensions to this specification are needed,
either this specification can be updated accordingly, or an
extension specification can be written that overrides the
requirements in this specification. When someone applying this
specification to their activities decides that they will recognize
the requirements of such an extension specification, it becomes an
<dfn title="other applicable specifications">applicable
specification</dfn> for the purposes of conformance requirements in
this specification.
<!-- http://www.w3.org/mid/17E341CD-E790-422C-9F9A-69347EE01CEB@iki.fi -->
<h2>Terminology</h2>
<p>The term <dfn>context object</dfn> means the object on which the method
or attribute being discussed was called. When the
<span>context object</span> is unambiguous, the term can be omitted.
<!-- XXX we should prolly explain that "set attribute X to Y" works even for
readonly attributes when it is language for implementors -->
<h3>Trees</h3> <!-- Sorry reddit, this is not /r/trees -->
<p>Just like most programming paradigms the Web platform has finite
hierarchical tree structures, simply named
<dfn title=concept-tree>trees</dfn>. The
<dfn title=concept-tree-order>tree order</dfn> is preorder, depth-first
traversal.
<!-- http://en.wikipedia.org/wiki/Tree_traversal#Depth-first_Traversal -->
<p>An object that <dfn title=concept-tree-participate>participates</dfn> in
a <span title=concept-tree>tree</span> has a
<dfn title=concept-tree-parent>parent</dfn>, which is either another object
or null, and an ordered list of zero or more
<dfn title=concept-tree-child>child</dfn> objects.
<p>The <dfn title=concept-tree-root>root</dfn> of an object is itself, if it
has no <span title=concept-tree-parent>parent</span>, or else it is the
<span title=concept-tree-root>root</span> of its
<span title=concept-tree-parent>parent</span>.
<p>An object <var title>A</var> is called a
<dfn title=concept-tree-descendant>descendant</dfn> of an object
<var title>B</var>, if either <var title>A</var> is a
<span title=concept-tree-child>child</span> of <var title>B</var> or
<var title>A</var> is a <span title=concept-tree-child>child</span> of an
object <var title>C</var> that is a
<span title=concept-tree-descendant>descendant</span> of <var title>B</var>.
<p>An
<dfn title=concept-tree-inclusive-descendant>inclusive descendant</dfn> is
an object or one of its
<span title=concept-tree-descendant>descendants</span>.
<p>An object <var title>A</var> is called an
<dfn title=concept-tree-ancestor>ancestor</dfn> of an object
<var title>B</var> if and only if <var title>B</var> is a
<span title=concept-tree-descendant>descendant</span> of
<var title>A</var>.
<p>An <dfn title=concept-tree-inclusive-ancestor>inclusive ancestor</dfn> is
an object or one of its <span title=concept-tree-ancestor>ancestors</span>.
<p>An object <var title>A</var> is called a
<dfn title=concept-tree-sibling>sibling</dfn> of an object
<var title>B</var>, if and only if <var title>B</var> and <var title>A</var>
share the same non-null <span title=concept-tree-parent>parent</span>.
<p>An object <var title>A</var> is
<dfn title=concept-tree-preceding>preceding</dfn> an object
<var title>B</var> if <var title>A</var> and <var title>B</var> are in the
same <span title=concept-tree>tree</span> and <var title>A</var> comes
before <var title>B</var> in
<span title=concept-tree-order>tree order</span>.
<p>An object <var title>A</var> is
<dfn title=concept-tree-following>following</dfn> an object
<var title>B</var> if <var title>A</var> and <var title>B</var> are in the
same <span title=concept-tree>tree</span> and <var title>A</var> comes
after <var title>B</var> in
<span title=concept-tree-order>tree order</span>.
<p>The <dfn title=concept-tree-first-child>first child</dfn> of an object is
its first <span title=concept-tree-child>child</span> or null if it has no
<span title=concept-tree-child>child</span>.
<p>The <dfn title=concept-tree-last-child>last child</dfn> of an object is
its last <span title=concept-tree-child>child</span> or null if it has no
<span title=concept-tree-child>child</span>.
<p>The <dfn title=concept-tree-previous-sibling>previous sibling</dfn> of an
object is its first <span title=concept-tree-preceding>preceding</span>
<span title=concept-tree-sibling>sibling</span> or null if it has no
<span title=concept-tree-preceding>preceding</span>
<span title=concept-tree-sibling>sibling</span>.
<p>The <dfn title=concept-tree-next-sibling>next sibling</dfn> of an
object is its first <span title=concept-tree-following>following</span>
<span title=concept-tree-sibling>sibling</span> or null if it has no
<span title=concept-tree-following>following</span>
<span title=concept-tree-sibling>sibling</span>.
<p>The <dfn title=concept-tree-index>index</dfn> of an object is its number
of <span title=concept-tree-preceding>preceding</span>
<span title=concept-tree-sibling>siblings</span>.
<h3>Strings</h3>
<p>Comparing two strings in a <dfn>case-sensitive</dfn> manner means comparing them exactly, code point for code point.
<p>Comparing two strings in a <dfn>ASCII case-insensitive</dfn> 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.
<p><dfn title="converted to ascii uppercase">Converting a string to ASCII uppercase</dfn> means replacing all characters in the range U+0061 to U+007A (i.e. LATIN SMALL LETTER A to LATIN SMALL LETTER Z) with the corresponding characters in the range U+0041 to U+005A (i.e. LATIN CAPITAL LETTER A to LATIN CAPITAL LETTER Z).
<p><dfn title="converted to ascii lowercase">Converting a string to ASCII lowercase</dfn> means replacing all characters in the range U+0041 to U+005A (i.e. LATIN CAPITAL LETTER A to LATIN CAPITAL LETTER Z) with the corresponding characters in the range U+0061 to U+007A (i.e. LATIN SMALL LETTER A to LATIN SMALL LETTER Z).
<p>A string <var title>pattern</var> is a <dfn>prefix match</dfn> for a string
<var title>s</var> when <var title>pattern</var> is not longer than
<var title>s</var> and truncating <var title>s</var> to
<var title>pattern</var>'s length leaves the two strings as matches of each
other.
<p>The <dfn title="space character">space characters</dfn>, 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).
<h3>Common microsyntaxes</h3>
<h4>Common parser idioms</h4>
<p>Some of the micro-parsers described below follow the pattern of having an
<var title>input</var> variable that holds the string being parsed, and having a
<var title>position</var> variable pointing at the next character to parse in
<var title>input</var>.
<p>For parsers based on this pattern, a step that requires the user agent to
<dfn>collect a sequence of characters</dfn> means that the following algorithm
must be run, with <var title>characters</var> being the set of characters that
can be collected:
<ol>
<li><p>Let <var title>input</var> and <var title>position</var> be the same
variables as those of the same name in the algorithm that invoked these steps.
<li><p>Let <var title>result</var> be the empty string.
<li><p>While <var title>position</var> does not point past the end of
<var title>input</var> and the character at <var title>position</var> is one of
the <var title>characters</var>, append that character to the end of
<var title>result</var> and advance <var title>position</var> to the next
character in <var title>input</var>.
<li><p>Return <var title>result</var>.
</ol>
<p>The step <dfn>skip whitespace</dfn> means that the user agent
must <span>collect a sequence of characters</span> that are <span
title="space character">space characters</span>. The collected
characters are not used.
<h4>Space-separated tokens</h4>
<p>A <dfn>set of space-separated tokens</dfn> is a string containing
zero or more words (known as tokens) separated by one or more <span
title="space character">space characters</span>, where words consist
of any string of one or more characters, none of which are <span
title="space character">space characters</span>.
<p>A string containing a <span>set of space-separated tokens</span>
may have leading or trailing <span title="space character">space
characters</span>.
<p>An <dfn>unordered set of unique space-separated tokens</dfn> is a
<span>set of space-separated tokens</span> where none of the tokens
are duplicated.
<p>An <dfn>ordered set of unique space-separated tokens</dfn> is a
<span>set of space-separated tokens</span> where none of the tokens
are duplicated but where the order of the tokens is meaningful.
<p><span title="set of space-separated tokens">Sets of
space-separated tokens</span> 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.
<p class="note">How tokens in a <span>set of space-separated
tokens</span> are to be compared (e.g. case-sensitively or not) is
defined on a per-set basis.
<div class="impl">
<p>When a user agent has to <dfn>split a string on spaces</dfn>, it
must use the following algorithm:
<ol>
<li><p>Let <var title>input</var> be the string being parsed.
<li><p>Let <var title>position</var> be a pointer into <var title>input</var>,
initially pointing at the start of the string.
<li><p>Let <var title>tokens</var> be a list of tokens, initially empty.
<li><p><span>Skip whitespace</span>.
<li><p>While <var title>position</var> is not past the end of
<var title>input</var>:
<ol>
<li><p><span>Collect a sequence of characters</span> that are not
<span title="space character">space characters</span>.
<li><p>Add the string collected in the previous step to
<var title>tokens</var>.
<li><p><span>Skip whitespace</span>.
</ol>
<li><p>Return <var title>tokens</var>.
</ol>
<p>When a user agent has to <dfn>remove a token from a string</dfn>,
it must use the following algorithm:
<ol>
<li><p>Let <var title>input</var> be the string being modified.
<li><p>Let <var title>token</var> be the token being removed. It will not
contain any <span title="space character">space characters</span>.
<li><p>Let <var title>output</var> be the output string, initially empty.
<li><p>Let <var title>position</var> be a pointer into <var title>input</var>,
initially pointing at the start of the string.
<li><p><i title>Loop</i>: If <var title>position</var> is beyond the end of
<var title>input</var>, terminate these steps.
<li>
<p>If the character at <var title>position</var> is a <span>space
character</span>:
<ol>
<li><p>Append the character at <var title>position</var> to the end of <var
title>output</var>.
<li><p>Advance <var title>position</var> so it points at the next character
in <var title>input</var>.
<li><p>Return to the step labeled <i title>loop</i>.
</ol>
<li><p>Otherwise, the character at <var title>position</var> is the first
character of a token. <span>Collect a sequence of characters</span> that are
not <span title="space character">space characters</span>, and let that be <var
title>s</var>.
<li>
<p>If <var title>s</var> is exactly equal to <var title>token</var>, then:
<ol>
<li><p><span>Skip whitespace</span> (in <var title>input</var>).
<li><p>Remove any <span title="space character">space characters</span>
currently at the end of <var title>output</var>.
<li><p>If <var title>position</var> is not past the end of <var
title>input</var>, and <var title>output</var> is not the empty string,
append a single U+0020 SPACE character at the end of <var title>output</var>.
</ol>
<li><p>Otherwise, append <var title>s</var> to the end of <var
title>output</var>.
<li><p>Return to the step labeled <i title>loop</i>.
</ol>
<p class="note">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.
</div>
<h3>Namespaces</h3>
<p>The <dfn>HTML namespace</dfn> is <code
title>http://www.w3.org/1999/xhtml</code>.
<p>The <dfn>XML namespace</dfn> is <code
title>http://www.w3.org/XML/1998/namespace</code>.
<p>The <dfn>XMLNS namespace</dfn> is <code
title>http://www.w3.org/2000/xmlns/</code>.
<h2>Errors</h2>
<h3>Exception <code>DOMException</code></h3>
<pre class=idl>exception <dfn>DOMException</dfn> {
const unsigned short <span title=dom-DOMException-INDEX_SIZE_ERR>INDEX_SIZE_ERR</span> = 1;
const unsigned short <span title=dom-DOMException-DOMSTRING_SIZE_ERR>DOMSTRING_SIZE_ERR</span> = 2; // historical
const unsigned short <span title=dom-DOMException-HIERARCHY_REQUEST_ERR>HIERARCHY_REQUEST_ERR</span> = 3;
const unsigned short <span title=dom-DOMException-WRONG_DOCUMENT_ERR>WRONG_DOCUMENT_ERR</span> = 4;
const unsigned short <span title=dom-DOMException-INVALID_CHARACTER_ERR>INVALID_CHARACTER_ERR</span> = 5;
const unsigned short <span title=dom-DOMException-NO_DATA_ALLOWED_ERR>NO_DATA_ALLOWED_ERR</span> = 6; // historical
const unsigned short <span title=dom-DOMException-NO_MODIFICATION_ALLOWED_ERR>NO_MODIFICATION_ALLOWED_ERR</span> = 7;
const unsigned short <span title=dom-DOMException-NOT_FOUND_ERR>NOT_FOUND_ERR</span> = 8;
const unsigned short <span title=dom-DOMException-NOT_SUPPORTED_ERR>NOT_SUPPORTED_ERR</span> = 9;
const unsigned short <span title=dom-DOMException-INUSE_ATTRIBUTE_ERR>INUSE_ATTRIBUTE_ERR</span> = 10; // historical
const unsigned short <span title=dom-DOMException-INVALID_STATE_ERR>INVALID_STATE_ERR</span> = 11;
const unsigned short <span title=dom-DOMException-SYNTAX_ERR>SYNTAX_ERR</span> = 12;
const unsigned short <span title=dom-DOMException-INVALID_MODIFICATION_ERR>INVALID_MODIFICATION_ERR</span> = 13;
const unsigned short <span title=dom-DOMException-NAMESPACE_ERR>NAMESPACE_ERR</span> = 14;
const unsigned short <span title=dom-DOMException-INVALID_ACCESS_ERR>INVALID_ACCESS_ERR</span> = 15;
const unsigned short <span title=dom-DOMException-VALIDATION_ERR>VALIDATION_ERR</span> = 16; // historical
const unsigned short <span title=dom-DOMException-TYPE_MISMATCH_ERR>TYPE_MISMATCH_ERR</span> = 17; // historical; use TypeError instead
const unsigned short <span title=dom-DOMException-SECURITY_ERR>SECURITY_ERR</span> = 18;
const unsigned short <span title=dom-DOMException-NETWORK_ERR>NETWORK_ERR</span> = 19;
const unsigned short <span title=dom-DOMException-ABORT_ERR>ABORT_ERR</span> = 20;
const unsigned short <span title=dom-DOMException-URL_MISMATCH_ERR>URL_MISMATCH_ERR</span> = 21;
const unsigned short <span title=dom-DOMException-QUOTA_EXCEEDED_ERR>QUOTA_EXCEEDED_ERR</span> = 22;
const unsigned short <span title=dom-DOMException-TIMEOUT_ERR>TIMEOUT_ERR</span> = 23;
const unsigned short <span title=dom-DOMException-INVALID_NODE_TYPE_ERR>INVALID_NODE_TYPE_ERR</span> = 24;
const unsigned short <span title=dom-DOMException-DATA_CLONE_ERR>DATA_CLONE_ERR</span> = 25;
unsigned short <span title=dom-DOMException-code>code</span>;
};</pre>
<p>The <dfn title=dom-DOMException-code><code>code</code></dfn> exception
field must return the value it was initialized to. When an exception is
created it must be initialized to zero.
<p>To <dfn title=concept-throw>throw</dfn> a <var title>name</var> exception
these steps must be run:
<ol>
<li><p>Create a new <code>DOMException</code> exception whose
<span data-anolis-spec=webidl>name</span> is <var title>name</var>.
<li><p>Set its <span data-anolis-spec=webidl>message</span> to a
user agent-defined value.
<li><p>If its <span data-anolis-spec=webidl>name</span> is in the first
column of the <span>error names table</span> and has a corresponding legacy
<code title=dom-DOMException-code>code</code> exception field value in the
third column, set its <code title=dom-DOMException-code>code</code>
exception field to that value.
<li><p><span data-anolis-spec=webidl>Throw</span> the exception.
</ol>
<p class=example>To
<i title>throw a "<code>TimeoutError</code>" exception</i>, a
user agent would construct a <code>DOMException</code> exception whose
<span data-anolis-spec=webidl>name</span> is
"<code>TimeoutError</code>" and
<code title=dom-DOMException-code>code</code> exception field value is 23,
and actually throw that object as an exception. In JavaScript, this
exception will have a <code title>name</code> property whose value is
"<code>TimeoutError</code>".
<h3>Interface <code>DOMError</code></h3>
<p class=note>This interface is intended for other specifications that want
to introduce error handling through other means than exceptions. As with
exceptions, the <span>error names table</span> is used.
<pre class=idl>interface <dfn>DOMError</dfn> {
readonly attribute DOMString <span title=dom-DOMError-name>name</span>;
};</pre>
<p>The <dfn title=dom-DOMError-name><code>name</code></dfn> attribute must
return the value it was initialized to.
<p>A
<dfn title=concept-DOMError><var title>name</var> <code>DOMError</code></dfn>
means a <code>DOMError</code> object whose
<code title=dom-DOMError-name>name</code> attribute is initialized to
<var title>name</var>.
<p class=example>A specification could say that an <code title>error</code>
attribute must return a
<span title=concept-DOMError>"<code>SyntaxError</code>" <code>DOMError</code></span>.
<h3>Error names</h3>
<p>The <dfn>error names table</dfn> below lists all the allowed error names,
a description, and legacy <code title=dom-DOMException-code>code</code>
exception field values (when the error name is used for
<span title=concept-throw>throwing</span> an exception).
<p class=note>If an error name is not listed here, please file a bug as
indicated at the top of this specification and it will be addressed shortly.
Thanks!
<table id=error-names>
<thead>
<tr><th>Name<th>Description<th>Legacy <code title=dom-DOMException-code>code</code> exception field value (if any)
<tbody>
<tr>
<td>"<dfn><code>IndexSizeError</code></dfn>"
<td>The index is not in the allowed range.
<td><dfn title=dom-DOMException-INDEX_SIZE_ERR><code>INDEX_SIZE_ERR</code></dfn> (1)
<tr>
<td>"<dfn><code>HierarchyRequestError</code></dfn>"
<td>The operation would yield an incorrect <span title=concept-node-tree>node tree</span>.
<td><dfn title=dom-DOMException-HIERARCHY_REQUEST_ERR><code>HIERARCHY_REQUEST_ERR</code></dfn> (3)
<tr>
<td>"<dfn><code>WrongDocumentError</code></dfn>"
<td>The object is in the wrong <span title=concept-document>document</span>.
<td><dfn title=dom-DOMException-WRONG_DOCUMENT_ERR><code>WRONG_DOCUMENT_ERR</code></dfn> (4)
<tr>
<td>"<dfn><code>InvalidCharacterError</code></dfn>"
<td>The string contains invalid characters.
<td><dfn title=dom-DOMException-INVALID_CHARACTER_ERR><code>INVALID_CHARACTER_ERR</code></dfn> (5)
<tr>
<td>"<dfn><code>NoModificationAllowedError</code></dfn>"
<td>The object can not be modified.
<td><dfn title=dom-DOMException-NO_MODIFICATION_ALLOWED_ERR><code>NO_MODIFICATION_ALLOWED_ERR</code></dfn> (7)
<tr>
<td>"<dfn><code>NotFoundError</code></dfn>"
<td>The object can not be found here.
<td><dfn title=dom-DOMException-NOT_FOUND_ERR><code>NOT_FOUND_ERR</code></dfn> (8)
<tr>
<td>"<dfn><code>NotSupportedError</code></dfn>"
<td>The operation is not supported.
<td><dfn title=dom-DOMException-NOT_SUPPORTED_ERR><code>NOT_SUPPORTED_ERR</code></dfn> (9)
<tr>
<td>"<dfn><code>InvalidStateError</code></dfn>"
<td>The object is in an invalid state.
<td><dfn title=dom-DOMException-INVALID_STATE_ERR><code>INVALID_STATE_ERR</code></dfn> (11)
<tr>
<td>"<dfn><code>SyntaxError</code></dfn>"
<td>The string did not match the expected pattern.
<td><dfn title=dom-DOMException-SYNTAX_ERR><code>SYNTAX_ERR</code></dfn> (12)
<tr>
<td>"<dfn><code>InvalidModificationError</code></dfn>"
<td>The object can not be modified in this way.
<td><dfn title=dom-DOMException-INVALID_MODIFICATION_ERR><code>INVALID_MODIFICATION_ERR</code></dfn> (13)
<tr>
<td>"<dfn><code>NamespaceError</code></dfn>"
<td>The operation is not allowed by <cite>Namespaces in XML</cite>. <span data-anolis-ref>XMLNS</span>
<td><dfn title=dom-DOMException-NAMESPACE_ERR><code>NAMESPACE_ERR</code></dfn> (14)
<tr>
<td>"<dfn><code>InvalidAccessError</code></dfn>"
<td>The object does not support the operation or argument.
<td><dfn title=dom-DOMException-INVALID_ACCESS_ERR><code>INVALID_ACCESS_ERR</code></dfn> (15)
<tr>
<!-- XHR -->
<td>"<dfn><code>SecurityError</code></dfn>"
<td>The operation is insecure.
<td><dfn title=dom-DOMException-SECURITY_ERR><code>SECURITY_ERR</code></dfn> (18)
<tr>
<!-- XHR -->
<td>"<dfn><code>NetworkError</code></dfn>"
<td>A network error occurred.
<td><dfn title=dom-DOMException-NETWORK_ERR><code>NETWORK_ERR</code></dfn> (19)
<tr>
<!-- XHR -->
<td>"<dfn><code>AbortError</code></dfn>"
<td>The operation was aborted.
<td><dfn title=dom-DOMException-ABORT_ERR><code>ABORT_ERR</code></dfn> (20)
<tr>
<!-- Workers -->
<td>"<dfn><code>URLMismatchError</code></dfn>"
<td>The given URL does not match another URL.
<td><dfn title=dom-DOMException-URL_MISMATCH_ERR><code>URL_MISMATCH_ERR</code></dfn> (21)
<tr>
<!-- HTML -->
<td>"<dfn><code>QuotaExceededError</code></dfn>"
<td>The quota has been exceeded.
<td><dfn title=dom-DOMException-QUOTA_EXCEEDED_ERR><code>QUOTA_EXCEEDED_ERR</code></dfn> (22)
<tr>
<!-- XHR -->
<td>"<dfn><code>TimeoutError</code></dfn>"
<td>The operation timed out.
<td><dfn title=dom-DOMException-TIMEOUT_ERR><code>TIMEOUT_ERR</code></dfn> (23)
<tr>
<td>"<dfn><code>InvalidNodeTypeError</code></dfn>"
<td>The supplied node is incorrect or has an incorrect ancestor for this operation.
<td><dfn title=dom-DOMException-INVALID_NODE_TYPE_ERR><code>INVALID_NODE_TYPE_ERR</code></dfn> (24)
<tr>
<!-- HTML -->
<td>"<dfn><code>DataCloneError</code></dfn>"
<td>The object can not be cloned.
<td><dfn title=dom-DOMException-DATA_CLONE_ERR><code>DATA_CLONE_ERR</code></dfn> (25)
<tr>
<td>"<dfn><code>EncodingError</code></dfn>"
<td>The encoding operation (either encoded or decoding) failed.
<td>—
</table>
<h2>Events</h2>
<h3>Introduction to "DOM Events"</h3>
<p>Throughout the web platform <span title=concept-event>events</span> are
<span title=concept-event-dispatch>dispatched</span> to objects to signal an
occurrence, such as network activity or user interaction. These objects
implement the <code>EventTarget</code> interface and can therefore add
<span title=concept-event-listener>event listeners</span> to observe
<span title=concept-event>events</span>:
<pre><code>obj.addEventListener("load", imgFetched)
function imgFetched(ev) {
// great success
…
}</code></pre>
<p><span title=concept-event-listener>Event listeners</span> can be removed
by utilizing the
<code title=dom-EventTarget-removeEventListener>removeEventListener()</code>
method, passing the same arguments.
<p><span title=concept-event>Events</span> are objects too and implement the
<code>Event</code> interface (or a derived interface). In the example above
<var title>ev</var> is the <span title=concept-event>event</span>. It is
passed as argument to
<span title=concept-event-listener>event listener</span>'s <b>callback</b>
(typically a JavaScript Function as shown above).
<span title=concept-event-listener>Event listeners</span> key off the
<span title=concept-event>event</span>'s
<code title=dom-Event-type>type</code> attribute value
("<code title>load</code>" in the above example). The
<span title=concept-event>event</span>'s
<code title=dom-Event-target>target</code> attribute value returns the
object to which the <span title=concept-event>event</span> was
<span title=concept-event-dispatch>dispatched</span> (<var title>obj</var>
above).
<p>Now while typically <span title=concept-event>events</span> are
<span title=concept-event-dispatch>dispatched</span> by the user agent as
the result of user interaction or the completion of some task, applications
can <span title=concept-event-dispatch>dispatch</span>
<span title=concept-event>events</span> themselves, commonly known as
synthetic events:
<pre><code>// add an appropriate event listener
obj.addEventListener("cat", function(e) { process(e.detail) })
// create and dispatch the event
var event = new CustomEvent("cat", {"detail":{"hazcheeseburger":true}})
obj.dispatchEvent(event)</code></pre>
<p>Apart from signaling, <span title=concept-event>events</span> are
sometimes also used to let an application control what happens next in an
operation. For instance as part of form submission an
<span title=concept-event>event</span> whose
<code title=dom-Event-type>type</code> attribute value is
"<code title>submit</code>" is
<span title=concept-event-dispatch>dispatched</span>. If this
<span title=concept-event>event</span>'s
<code title=dom-Event-preventDefault>preventDefault()</code> method is
invoked, form submission will be terminated. Applications who wish to make
use of this functionality through <span title=concept-event>events</span>
<span title=concept-event-dispatch>dispatched</span> by the application
(synthetic events) can make use of the return value of the
<code title=dom-EventTarget-dispatchEvent>dispatchEvent()</code> method:
<pre><code>if(obj.dispatchEvent(event)) {
// event was not canceled, time for some magic
…
}</code></pre>
<p>When an <span title=concept-event>event</span> is
<span title=concept-event-dispatch>dispatched</span> to an object that
<span title=concept-tree-participate>participates</span> in a
<span title=concept-tree>tree</span> (e.g. an
<span title=concept-element>element</span>), it can reach
<span title=concept-event-listener>event listeners</span> on that object's
<span title=concept-tree-ancestor>ancestors</span> too. First all object's
<span title=concept-tree-ancestor>ancestor</span>
<span title=concept-event-listener>event listeners</span> whose
<b>capture</b> variable is set to true are invoked, in
<span title=concept-tree-order>tree order</span>. Second, object's own
<span title=concept-event-listener>event listeners</span> are invoked. And
finally, and only if <span title=concept-event>event</span>'s
<span title=dom-Event-bubbles>bubbles</span> attribute value is true,
object's <span title=concept-tree-ancestor>ancestor</span>
<span title=concept-event-listener>event listeners</span> are invoked again,
but now in reverse <span title=concept-tree-order>tree order</span>.
<p>Lets look at an example on how <span title=concept-event>events</span>
work in a <span title=concept-tree>tree</span>:
<pre><code><!doctype html>
<html>
<head>
<title>Boring example</title>
</head>
<body>
<p>Hello <span id=x>world</span>!</p>
<script>
function test(e) {
debug(e.target, e.currentTarget, e.eventPhase)
}
document.addEventListener("hey", test, true)
document.body.addEventListener("hey", test)
var ev = new Event("hey", {bubbles:true})
document.getElementById("x").dispatchEvent(ev)
</script>
</body>
</html></code></pre>
<p>The <code title>debug</code> function will be invoked twice. Each time
the <span title=concept-event>events</span>'s
<code title=dom-Event-target>target</code> attribute value will be the
<code title>span</code> <span title=concept-element>element</span>. The
first time <code title=dom-Event-target>currentTarget</code> attribute's
value will be the <span title=concept-document>document</span>, the second
time the <code title>body</code> <span title=concept-element>element</span>.
<code title=dom-Event-eventPhase>eventPhase</code> attribute's value
switches from <code title=dom-Event-CAPTURING_PHASE>CAPTURING_PHASE</code>
to <code title=dom-Event-BUBBLING_PHASE>BUBBLING_PHASE</code>. If an
<span title=concept-event-listener>event listener</span> was registered for
the <code title>span</code> <span title=concept-element>element</span>,
<code title=dom-Event-eventPhase>eventPhase</code> attribute's value
would have been <code title=dom-Event-AT_TARGET>AT_TARGET</code>.
<h3>Interface <code>Event</code></h3>
<pre class="idl">[Constructor(DOMString <var title>type</var>, optional <span>EventInit</span> <var title>eventInitDict</var>)]
interface <dfn>Event</dfn> {
readonly attribute DOMString <span title=dom-Event-type>type</span>;
readonly attribute <span>EventTarget</span>? <span title=dom-Event-target>target</span>;
readonly attribute <span>EventTarget</span>? <span title=dom-Event-currentTarget>currentTarget</span>;
const unsigned short <span title=dom-Event-NONE>NONE</span> = 0;
const unsigned short <span title=dom-Event-CAPTURING_PHASE>CAPTURING_PHASE</span> = 1;
const unsigned short <span title=dom-Event-AT_TARGET>AT_TARGET</span> = 2;
const unsigned short <span title=dom-Event-BUBBLING_PHASE>BUBBLING_PHASE</span> = 3;
readonly attribute unsigned short <span title=dom-Event-eventPhase>eventPhase</span>;
void <span title=dom-Event-stopPropagation>stopPropagation</span>();
void <span title=dom-Event-stopImmediatePropagation>stopImmediatePropagation</span>();
readonly attribute boolean <span title=dom-Event-bubbles>bubbles</span>;
readonly attribute boolean <span title=dom-Event-cancelable>cancelable</span>;
void <span title=dom-Event-preventDefault>preventDefault</span>();
readonly attribute boolean <span title=dom-Event-defaultPrevented>defaultPrevented</span>;
readonly attribute boolean <span title=dom-Event-isTrusted>isTrusted</span>;
readonly attribute DOMTimeStamp <span title=dom-Event-timeStamp>timeStamp</span>;
void <span title=dom-Event-initEvent>initEvent</span>(DOMString <var title>type</var>, boolean <var title>bubbles</var>, boolean <var title>cancelable</var>);
};
dictionary <dfn>EventInit</dfn> {
boolean <span title=dom-EventInit-bubbles>bubbles</span>;
boolean <span title=dom-EventInit-cancelable>cancelable</span>;
};</pre>
<p>An <dfn title=concept-event>event</dfn> allows for signaling that
something has occurred. E.g. that an image has completed downloading. It is
represented by the <code>Event</code> interface or an interface that
inherits from the <code>Event</code> interface.</p>
<dl class=domintro>
<dt><code>var <var title>event</var> = new Event(<var title>type</var> [, <var title>eventInitDict</var>])</code>
<dd><p>Returns a new <var title>event</var> whose
<code title=dom-Event-type>type</code> attribute value is set to
<var title>type</var>. The optional <var title>eventInitDict</var> argument
allows for setting the <code title=dom-Event-bubbles>bubbles</code> and
<code title=dom-Event-cancelable>cancelable</code> attributes via object
members of the same name.
<dt><code><var title>event</var> . <span title=dom-Event-type>type</span></code>
<dd><p>Returns the type of <var title>event</var>, e.g.
"<code title>click</code>", "<code title>hashchange</code>", or
"<code title>submit</code>".
<dt><code><var title>event</var> . <span title=dom-Event-target>target</span></code>
<dd><p>Returns the object <var title>event</var> is
<span title=concept-event-dispatch>dispatched</span> to.
<dt><code><var title>event</var> . <span title=dom-Event-currentTarget>currentTarget</span></code>
<dd><p>Returns the object whose
<span title=concept-event-listener>event listener</span>'s <b>callback</b>
is invoked.
<dt><code><var title>event</var> . <span title=dom-Event-eventPhase>eventPhase</span></code>
<dd><p>Returns the <span title=concept-event>event</span>'s phase, which is
one of <code title=dom-Event-NONE>NONE</code>,
<code title=dom-Event-CAPTURING_PHASE>CAPTURING_PHASE</code>,
<code title=dom-Event-AT_TARGET>AT_TARGET</code>, and
<code title=dom-Event-BUBBLING_PHASE>BUBBLING_PHASE</code>.
<dt><code><var title>event</var> . <span title=dom-Event-stopPropagation>stopPropagation</span>()</code>
<dd><p>When <span title=concept-event-dispatch>dispatched</span> in a
<span title=concept-tree>tree</span>, invoking this method prevents
<var title>event</var> from reaching any other objects than the current.
<dt><code><var title>event</var> . <span title=dom-Event-stopImmediatePropagation>stopImmediatePropagation</span>()</code>
<dd><p>Invoking this method prevents <var title>event</var> from reaching
any <span title=concept-event-listener>event listeners</span> registered
after the current one and when
<span title=concept-event-dispatch>dispatched</span> in a
<span title=concept-tree>tree</span> also prevents
<var title>event</var> from reaching any other objects.
<dt><code><var title>event</var> . <span title=dom-Event-bubbles>bubbles</span></code>
<dd><p>Returns true if <var title>event</var>'s goes through its <code title=dom-Event-target>target</code> attribute value's <span title=concept-tree-ancestor>ancestors</span> in reverse <span title=concept-tree-order>tree order</span>, and false otherwise.
<dt><code><var title>event</var> . <span title=dom-Event-cancelable>cancelable</span></code>
<dd><p>Returns true or false depending on how <var title>event</var> was
initialized. Its return value does not always carry meaning, but true can
indicate that part of the operation during which <var title>event</var> was
<span title=concept-event-dispatch>dispatched</span>, can be canceled by
invoking the <code title=dom-Event-preventDefault>preventDefault()</code>
method.
<dt><code><var title>event</var> . <span title=dom-Event-preventDefault>preventDefault</span>()</code>
<dd><p>If invoked when the
<code title=dom-Event-cancelable>cancelable</code> attribute value is true,
signals to the operation that caused <var title>event</var> to be
<span title=concept-event-dispatch>dispatched</span> that it needs to be
canceled.
<dt><code><var title>event</var> . <span title=dom-Event-defaultPrevented>defaultPrevented</span></code>
<dd><p>Returns true if
<code title=dom-Event-preventDefault>preventDefault()</code> was invoked
while the <code title=dom-Event-cancelable>cancelable</code> attribute
value is true, and false otherwise.
<dt><code><var title>event</var> . <span title=dom-Event-isTrusted>isTrusted</span></code>
<dd><p>Returns true if <var title>event</var> was
<span title=concept-event-dispatch>dispatched</span> by the user agent, and
false otherwise.
<dt><code><var title>event</var> . <span title=dom-Event-timeStamp>timeStamp</span></code>
<dd><p>Returns the creation time of <var title>event</var> in the number of
milliseconds that passed since 00:00:00 UTC on 1 January 1970.
<!-- initEvent is dead -->
</dl>
<p>The <dfn title=dom-Event-type><code>type</code></dfn> attribute must
return the value it was initialized to. When an
<span title=concept-event>event</span> is created the attribute must be
initialized to the empty string.
<p>The <dfn title=dom-Event-target><code>target</code></dfn> and
<dfn title=dom-Event-currentTarget><code>currentTarget</code></dfn>
attributes must return the values they were initialized to. When an
<span title=concept-event>event</span> is created the attributes must be
initialized to null.
<p>The <dfn title=dom-Event-eventPhase><code>eventPhase</code></dfn>
attribute must return the value it was initialized to, which must be one of
the following:</p>
<dl>
<dt><dfn title=dom-Event-NONE><code>NONE</code></dfn> (numeric value 0)
<dd><p><span title=concept-event>Events</span> not currently
<span title=concept-event-dispatch>dispatched</span> are in this phase.
<dt><dfn title=dom-Event-CAPTURING_PHASE><code>CAPTURING_PHASE</code></dfn> (numeric value 1)</dt>
<dd><p>When an <span title=concept-event>event</span> is
<span title=concept-event-dispatch>dispatched</span> to an object that
<span title=concept-tree-participate>participates</span> in a
<span title=concept-tree>tree</span> it will be in this phase before it
reaches its <code title=dom-Event-target>target</code> attribute value.
<dt><dfn title=dom-Event-AT_TARGET><code>AT_TARGET</code></dfn> (numeric value 2)
<dd><p>When an <span title=concept-event>event</span> is
<span title=concept-event-dispatch>dispatched</span> it will be in this
phase on its <code title=dom-Event-target>target</code> attribute value.
<dt><dfn title=dom-Event-BUBBLING_PHASE><code>BUBBLING_PHASE</code></dfn> (numeric value 3)
<dd><p>When an <span title=concept-event>event</span> is
<span title=concept-event-dispatch>dispatched</span> to an object that
<span title=concept-tree-participate>participates</span> in a
<span title=concept-tree>tree</span> it will be in this phase after it
reaches its <code title=dom-Event-target>target</code> attribute value.
</dl>
<p>Initially the attribute must be initialized to
<code title=dom-Event-NONE>NONE</code>.
<hr>
<p>Each <span title=concept-event>event</span> has the following associated
flags that are all initially unset:</p>
<ul>
<li><dfn>stop propagation flag</dfn>
<li><dfn>stop immediate propagation flag</dfn>
<li><dfn>canceled flag</dfn>
<li><dfn>initialized flag</dfn>
<li><dfn>dispatch flag</dfn>
</ul>
<p>When the
<dfn title=dom-Event-stopPropagation><code>stopPropagation()</code></dfn>
method is invoked the <span>stop propagation flag</span> must be set.
<p>When the
<dfn title=dom-Event-stopImmediatePropagation><code>stopImmediatePropagation()</code></dfn>
method is invoked both the <span>stop propagation flag</span> and
<span>stop immediate propagation flag</span> must be set.
<p>The <dfn title=dom-Event-bubbles><code>bubbles</code></dfn> and
<dfn title=dom-Event-cancelable><code>cancelable</code></dfn> attributes
must return the values they were initialized to. When an
<span title=concept-event>event</span> is created the attributes must be
initialized to false.
<p>When the
<dfn title=dom-Event-preventDefault><code>preventDefault()</code></dfn>
method is invoked and the <code title=dom-Event-cancelable>cancelable</code>
attribute is true, the <span>canceled flag</span> must be set.
<p>The <dfn title=dom-Event-defaultPrevented><code>defaultPrevented</code></dfn>
attribute must return true if the <span>canceled flag</span> is set and
false otherwise.
<hr>
<p>The <dfn title=dom-Event-isTrusted><code>isTrusted</code></dfn> attribute
must return the value it was initialized to. When an
<span title=concept-event>event</span> is created the attribute must be
initialized to false.
<p>The <dfn title=dom-Event-timeStamp><code>timeStamp</code></dfn> attribute
must return the value it was initialized to. When an