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<!doctype html>
<html lang="en-US">
<head>
<meta charset=utf-8>
<title>CSSOM View Module</title>
<style>
.propdef { font:inherit; line-height:2.3 }
</style>
<link rel=stylesheet href=../default.css>
<link rel="stylesheet" href="https://www.w3.org/StyleSheets/TR/W3C-[STATUS]">
</head>
<body class="draft">
<div class="head">
<!--logo-->
<h1>CSSOM View Module</h1>
<h2 class="no-num no-toc" id="w3c-doctype">[LONGSTATUS] [DATE: 3 August 2002]</h2>
<dl>
<dt>This Version:</dt>
<dd class=dontpublish><a href="http://dev.w3.org/csswg/cssom-view/">http://dev.w3.org/csswg/cssom-view/</a></dd>
<dd class=publish><a href="[VERSION]">[VERSION]</a></dd>
<dt class=dontpublish>Participate:</dt>
<dd class=dontpublish><a href="mailto:www-style@w3.org?subject=%5Bcssom-view%5D%20">www-style@w3.org</a>
(<a href="http://lists.w3.org/Archives/Public/www-style/">archives</a>)
<dd class=dontpublish><a href="https://www.w3.org/Bugs/Public/enter_bug.cgi?product=CSS&component=CSSOM%20View">File a bug</a>
(<a href="https://www.w3.org/Bugs/Public/buglist.cgi?component=CSSOM%20View&product=CSS&resolution=---">open bugs</a>)
<script async="" src="http://resources.whatwg.org/file-bug.js"></script>
<dd class=dontpublish><a href="irc://irc.w3.org:6665/css">IRC: #css on W3C</a></dd>
<dt class=publish>Latest Version:</dt>
<dd class=publish><a href="[LATEST]">[LATEST]</a></dd>
<dt class=publish>Latest Editor Draft:</dt>
<dd class=publish><a href="http://dev.w3.org/csswg/cssom-view/">http://dev.w3.org/csswg/cssom-view/</a></dd>
<dt>Previous Versions:</dt>
<dd><a href="http://www.w3.org/TR/2009/WD-cssom-view-20090804/">http://www.w3.org/TR/2009/WD-cssom-view-20090804/</a></dd>
<dd><a href="http://www.w3.org/TR/2008/WD-cssom-view-20080222/">http://www.w3.org/TR/2008/WD-cssom-view-20080222/</a></dd>
<dd><a href="http://www.w3.org/TR/2000/REC-DOM-Level-2-Style-20001113/">http://www.w3.org/TR/2000/REC-DOM-Level-2-Style-20001113/</a></dd>
<dt>Editors:</dt>
<dd>Simon Pieters
(<a href="http://www.opera.com/">Opera Software ASA</a>)
<<a href="mailto:simonp@opera.com">simonp@opera.com</a>></dd>
<dd><a href="http://www.w3.org/wiki/User:Gadams">Glenn Adams</a>
(<a href="http://www.cox.com/">Cox Communications, Inc.</a>)
<<a href="mailto:glenn.adams@cox.com">glenn.adams@cox.com</a>></dd>
<dt>Previous Editor:</dt>
<dd><a href="http://annevankesteren.nl/">Anne van Kesteren</a>
(<a href="http://www.opera.com/">Opera Software ASA</a>)
<<a href="mailto:annevk@annevk.nl">annevk@annevk.nl</a>></dd>
</dl>
<!--copyright-->
</div>
<hr>
<h2 class="no-num no-toc">Abstract</h2>
<p>The APIs introduced by this specification provide authors with a way to
inspect and manipulate the visual view of a document. This includes
getting the position of element layout boxes, obtaining the width
of the viewport through script, and also scrolling an element.</p>
<h2 id="sotd" class="no-num no-toc">Status of This Document</h2>
<p><em>This section describes the status of this document at the time of
its publication. Other documents may supersede this document. A list of
current W3C publications and the latest revision of this technical report
can be found in the <a href="http://www.w3.org/TR/">W3C technical reports
index at http://www.w3.org/TR/.</a></em>
<p>This is the [DATE: 3 August 2002] [LONGSTATUS] of CSSOM View. Please send
comments to
<a href="mailto:www-style@w3.org?subject=%5Bcssom-view%5D%20">www-style@w3.org</a>
(<a href="http://lists.w3.org/Archives/Public/www-style/">archived</a>)
with <samp>[cssom-view]</samp> at the start of the subject line.
<p>This document was produced by the <a
href="http://www.w3.org/Style/CSS/members">CSS Working Group</a> (part of
the <a href="http://www.w3.org/Style/">Style Activity</a>).
<p>This document was produced by a group operating under the <a
href="http://www.w3.org/Consortium/Patent-Policy-20040205/">5 February
2004 W3C Patent Policy</a>. W3C maintains a <a
href="http://www.w3.org/2004/01/pp-impl/32061/status"
rel=disclosure>public list of any patent disclosures</a> made in
connection with the deliverables of the group; that page also includes
instructions for disclosing a patent. An individual who has actual
knowledge of a patent which the individual believes contains <a
href="http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential
Claim(s)</a> must disclose the information in accordance with <a
href="http://www.w3.org/Consortium/Patent-Policy-20040205/#sec-Disclosure">section
6 of the W3C Patent Policy</a>.</p>
<p>Publication as a Working Draft does not imply endorsement by the W3C
Membership. This is a draft document and may be updated, replaced or
obsoleted by other documents at any time. It is inappropriate to cite this
document as other than work in progress.
<h2 id="toc" class="no-num no-toc">Table of Contents</h2>
<!-- toc -->
<h2>Background</h2>
<p>Many of the features defined in this specification have been supported
by browsers for a long period of time. The goal of this specification is
to define these features in such a way that they can be implemented by all
browsers in an interoperable manner. The specification also defines a
couple of new features that will hopefully be useful to authors. (If they
are not you can bug us!)</p>
<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", "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. <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. <!--fingerprint-->
<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 data-anolis-spec=dom>case-sensitive</span> manner.
<p>A conforming user agent implements all the requirements made by this
specification.</p>
<h3>Web IDL</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>
<h2>Terminology</h2>
<p>Terminology used in this specification is from
DOM,
CSSOM and
HTML.
<span data-anolis-ref>DOM</span>
<span data-anolis-ref>CSSOM</span>
<span data-anolis-ref>HTML</span>
<p class="issue"><dfn><code>MouseEvent</code></dfn> and <dfn><code>MouseEventInit</code></dfn> are defined in …
<p><dfn><code>DOMPoint</code></dfn>,
<dfn><code>DOMPointReadOnly</code></dfn>,
<dfn><code>DOMPointInit</code></dfn>,
<dfn><code>DOMRect</code></dfn>,
<dfn><code>DOMRectReadOnly</code></dfn>,
<dfn><code>DOMRectList</code></dfn> and
<dfn><code>DOMQuad</code></dfn> are defined in Geometry Interfaces Module. <span data-anolis-ref>GEOMETRY</span>
<p><dfn>The HTML <code title>body</code> element</dfn> is the first
<code title>body</code>
<span data-anolis-spec=html title="HTML elements">HTML element</span> child of the root
<span data-anolis-spec=html title="HTML elements">HTML element</span> <code title>html</code>.</p>
<p><dfn>Content edge</dfn>,
<dfn>padding edge</dfn>,
<dfn>border edge</dfn>,
<dfn>margin edge</dfn> and
<dfn>canvas</dfn> are defined by CSS.
<!--<span data-anolis-ref>CSS</span>-->
<p><dfn>Viewport</dfn> and <dfn>initial containing block</dfn> are defined by CSS 2.1. <!--<span data-anolis-ref>CSS</span>-->
<p><dfn>Block flow direction</dfn> and <dfn>inline base direction</dfn> are defined in CSS Writing Modes Module. <span data-anolis-ref>CSSWRITINGMODES</span>
<p><dfn>Converted to an IDL value</dfn> is defined in Web IDL. <span data-anolis-ref>WEBIDL</span>
<p>Elements and <span title=viewport>viewports</span> have an associated <dfn>scrolling box</dfn> if has a scrolling mechanism<!--XXX xref--> or it overflows
its content area<!--XXX xref--> and the used value of the 'overflow-x' or 'overflow-y' property is 'hidden'. <span data-anolis-ref>CSSBOX</span>
<p>A <span>scrolling box</span> of a <span>viewport</span> or element has two <dfn>overflow directions</dfn>, depending on the <span>viewport</span>'s or
element's <span>block flow direction</span> and <span>inline base direction</span>, as follows:
<dl class=switch>
<dt>If the <span>block flow direction</span> is top-to-bottom and the <span>inline base direction</span> is left-to-right
<dt>If the <span>block flow direction</span> is left-to-right and the <span>inline base direction</span> is left-to-right
<dd><p>Rightward and downward.
<dt>If the <span>block flow direction</span> is top-to-bottom and the <span>inline base direction</span> is right-to-left
<dt>If the <span>block flow direction</span> is right-to-left and the <span>inline base direction</span> is left-to-right
<dd><p>Leftward and downward.
<dt>If the <span>block flow direction</span> is right-to-left and the <span>inline base direction</span> is right-to-left
<dd><p>Leftward and upward.
<dt>If the <span>block flow direction</span> is left-to-right and the <span>inline base direction</span> is right-to-left
<dd><p>Righward and upward.
</dl>
<p>The term <dfn>scrolling area</dfn> refers to a box of a <span>viewport</span> or an element that has the following edges, depending on the
<span>viewport</span>'s or element's <span>scrolling box</span>'s <span>overflow directions</span>.
<table class="complex data">
<thead>
<tr>
<th>If the <span>overflow directions</span> are…
<th>For a <span>viewport</span>
<th>For an element
<tbody>
<tr>
<td>rightward and downward
<td class=long>
<dl>
<dt>top edge
<dd><p>The top edge of the <span>initial containing block</span>.
<dt>right edge
<dd><p>The right-most edge of the right edge of the <span>initial containing block</span> and the right <span>margin edge</span> of the
<span>viewport</span>'s all descendant boxes.
<dt>bottom edge
<dd><p>The bottom-most edge of the bottom edge of the <span>initial containing block</span> and the bottom <span>margin edge</span> of the
<span>viewport</span>'s all descendant boxes.
<dt>left edge
<dd><p>The left edge of the <span>initial containing block</span>.
</dl>
<td class=long>
<dl>
<dt>top edge
<dd><p>The element's top <span>padding edge</span>.
<dt>right edge
<dd><p>The right-most edge of the element's right <span>padding edge</span> and the right <span>margin edge</span> of the element's all descendant boxes,
excluding boxes that have an ancestor of the element as their containing block.
<dt>bottom edge
<dd><p>The bottom-most edge of the element's bottom <span>padding edge</span> and the bottom <span>margin edge</span> of the element's all descendant
boxes, excluding boxes that have an ancestor of the element as their containing block.
<dt>left edge
<dd><p>The element's left <span>padding edge</span>.
</dl>
<tr>
<td>leftward and downward
<td class=long>
<dl>
<dt>top edge
<dd><p>The top edge of the <span>initial containing block</span>.
<dt>right edge
<dd><p>The right edge of the <span>initial containing block</span>.
<dt>bottom edge
<dd><p>The bottom-most edge of the bottom edge of the <span>initial containing block</span> and the bottom <span>margin edge</span> of the
<span>viewport</span>'s all descendant boxes.
<dt>left edge
<dd><p>The left-most edge of the left edge of the <span>initial containing block</span> and the left <span>margin edge</span> of the
<span>viewport</span>'s all descendant boxes.
</dl>
<td class=long>
<dl>
<dt>top edge
<dd><p>The element's top <span>padding edge</span>.
<dt>right edge
<dd><p>The element's right <span>padding edge</span>.
<dt>bottom edge
<dd><p>The bottom-most edge of the element's bottom <span>padding edge</span> and the bottom <span>margin edge</span> of the element's all descendant
boxes, excluding boxes that have an ancestor of the element as their containing block.
<dt>left edge
<dd><p>The left-most edge of the element's left <span>padding edge</span> and the left <span>margin edge</span> of the element's all descendant boxes,
excluding boxes that have an ancestor of the element as their containing block.
</dl>
<tr>
<td>leftward and upward
<td class=long>
<dl>
<dt>top edge
<dd><p>The top-most edge of the top edge of the <span>initial containing block</span> and the top <span>margin edge</span> of the
<span>viewport</span>'s all descendant boxes.
<dt>right edge
<dd><p>The right edge of the <span>initial containing block</span>.
<dt>bottom edge
<dd><p>The bottom edge of the <span>initial containing block</span>.
<dt>left edge
<dd><p>The left-most edge of the left edge of the <span>initial containing block</span> and the left <span>margin edge</span> of the
<span>viewport</span>'s all descendant boxes.
</dl>
<td class=long>
<dl>
<dt>top edge
<dd><p>The top-most edge of the element's top <span>padding edge</span> and the top <span>margin edge</span> of the element's all descendant boxes,
excluding boxes that have an ancestor of the element as their containing block.
<dt>right edge
<dd><p>The element's right <span>padding edge</span>.
<dt>bottom edge
<dd><p>The element's bottom <span>padding edge</span>.
<dt>left edge
<dd><p>The left-most edge of the element's left <span>padding edge</span> and the left <span>margin edge</span> of the element's all descendant boxes,
excluding boxes that have an ancestor of the element as their containing block.
</dl>
<tr>
<td>rightward and upward
<td class=long>
<dl>
<dt>top edge
<dd><p>The top-most edge of the top edge of the <span>initial containing block</span> and the top <span>margin edge</span> of the
<span>viewport</span>'s all descendant boxes.
<dt>right edge
<dd><p>The right-most edge of the right edge of the <span>initial containing block</span> and the right <span>margin edge</span> of the
<span>viewport</span>'s all descendant boxes.
<dt>bottom edge
<dd><p>The bottom edge of the <span>initial containing block</span>.
<dt>left edge
<dd><p>The left edge of the <span>initial containing block</span>.
</dl>
<td class=long>
<dl>
<dt>top edge
<dd><p>The top-most edge of the element's top <span>padding edge</span> and the top <span>margin edge</span> of the element's all descendant boxes,
excluding boxes that have an ancestor of the element as their containing block.
<dt>right edge
<dd><p>The right-most edge of the element's right <span>padding edge</span> and the right <span>margin edge</span> of the element's all descendant boxes,
excluding boxes that have an ancestor of the element as their containing block.
<dt>bottom edge
<dd><p>The element's bottom <span>padding edge</span>.
<dt>left edge
<dd><p>The element's left <span>padding edge</span>.
</dl>
</table>
<p>The <dfn title="scrolling area origin">origin</dfn> of a <span>scrolling area</span> is
the origin of the <span>initial containing block</span> if the <span>scrolling area</span> is a <span>viewport</span>,
and otherwise the top left padding edge of the element when the element has its default scroll position.
The x-coordinate increases rightwards, and the y-coordinate increases downwards.
<p>The <dfn>beginning edges</dfn> of a particular set of edges of a box or element are the following edges:
<dl class=switch>
<dt>If the <span>overflow directions</span> are rightward and downward
<dd><p>The top and left edges.
<dt>If the <span>overflow directions</span> are leftward and downward
<dd><p>The top and right edges.
<dt>If the <span>overflow directions</span> are leftward and upward
<dd><p>The bottom and right edges.
<dt>If the <span>overflow directions</span> are rightward and upward
<dd><p>The bottom and left edges.
</dl>
<p>The <dfn>ending edges</dfn> of a particular set of edges of a box or element are the following edges:
<dl class=switch>
<dt>If the <span>overflow directions</span> are rightward and downward
<dd><p>The bottom and right edges.
<dt>If the <span>overflow directions</span> are leftward and downward
<dd><p>The bottom and left edges.
<dt>If the <span>overflow directions</span> are leftward and upward
<dd><p>The top and left edges.
<dt>If the <span>overflow directions</span> are rightward and upward
<dd><p>The top and right edges.
</dl>
<p>The term <dfn>CSS layout box</dfn> refers to the same term in CSS. For the purpose
of the requirements in this specification, elements that have a computed value of the
'display' property that is 'table-column' or
'table-column-group' must be considered to have an associated <span>CSS
layout box</span> (the column or column group, respectively).</p>
<p>The term <dfn>SVG layout box</dfn> refers to the same term in SVG.
<p class=issue>The terms <span>CSS layout box</span> and <span>SVG layout box</span> are not currently defined by CSS or SVG.
<p>The term <dfn>layout box</dfn> refers to either a <span>CSS layout box</span> or an <span>SVG layout box</span>.
<p>The term <dfn>transforms</dfn> refers to SVG transforms and CSS transforms. <span data-anolis-ref>SVG</span> <span data-anolis-ref>CSSTRANSFORMS</span>
<h3>CSS pixels</h3>
<p>All coordinates and dimensions for the APIs defined in this
specification are in CSS pixels, unless otherwise specified. <!--<span data-anolis-ref>CSS</span>-->
<p class="note">This does not apply to e.g.
<code title=dom-Window-matchMedia>matchMedia()</code> as the units
are explicitly given there.</p>
<h3>Zooming</h3>
<p>There are two kinds of zoom, <dfn>page zoom</dfn> which affects the size of the initial viewport<!-- XXX ref -->, and <dfn>pinch zoom</dfn> which acts like
a magnifying glass and does not affect the initial viewport<!-- XXX ref --> or actual viewport<!-- XXX ref -->. <span data-anolis-ref>CSSDEVICEADAPT</span>
<h2>Common Infrastructure</h2>
<h3>Scrolling</h3>
<p>When a user agent is to <dfn>perform a scroll</dfn> of a <span>scrolling box</span> <var>box</var>, to a given position <var>position</var>, with a set of
steps <var>task</var>, an associated element <var>element</var> and optionally a scroll behavior <var>behavior</var> (which is
<code title>auto</code> if omitted), the following steps must be run:
<ol>
<li><p><span title=concept-smooth-scroll-aborted>Abort</span> any ongoing <span title=concept-smooth-scroll>smooth scroll</span> for <var>box</var>.
<li><p>If the user agent honors the '<span>scroll-behavior</span>' property and one of the following are true:
<ul>
<li><p><var>behavior</var> is <code title>auto</code> and <var>element</var> is not null and its computed value of the
'<span>scroll-behavior</span>' property is '<span title=scroll-behavior-smooth>smooth</span>'
<li><p><var>behavior</var> is <code title>smooth</code>
</ul>
<p>...then follow these substeps:
<ol>
<li><p>Perform a <span title=concept-smooth-scroll>smooth scroll</span> of <var>box</var> to <var>position</var>.
<li><p><span data-anolis-spec=html>Queue a task</span> to run <var>task</var>, unless a <span data-anolis-spec=html title=concept-task>task</span> to
run <var>task</var> is in the <span data-anolis-spec=html title="queue a task">queue</span>.
<li><p>Repeat the previous step in a user-agent-defined interval while the <span title=concept-smooth-scroll>smooth scroll</span> is ongoing, as well as when
the <span title=concept-smooth-scroll>smooth scroll</span> is <span title=concept-smooth-scroll-completed>completed</span> (but not if it is
<span title=concept-smooth-scroll-aborted>aborted</span>). <!--fingerprint-->
</ol>
<li><p>Otherwise, follow these substeps:
<ol>
<li><p>Perform an <span title=concept-instant-scroll>instant scroll</span> of <var>box</var> to <var>position</var>.
<li><p><span data-anolis-spec=html>Queue a task</span> to run <var>task</var>, unless a <span data-anolis-spec=html title=concept-task>task</span> to
run <var>task</var> is in the <span data-anolis-spec=html title="queue a task">queue</span>.
</ol>
</ol>
<p>When a user agent is to perform a <dfn title=concept-smooth-scroll>smooth scroll</dfn> of a <span>scrolling box</span> <var>box</var> to <var>position</var>,
it must update the scroll position of <var>box</var> in a user-agent-defined fashion over a user-agent-defined amount of time. When the scroll is
<dfn title="concept-smooth-scroll-completed">completed</dfn>, the scroll position of <var>box</var> must be <var>position</var>. The scroll can also
be <dfn title=concept-smooth-scroll-aborted>aborted</dfn>, either by an algorithm or by the user. <!--fingerprint-->
<p>When a user agent is to perform an <dfn title=concept-instant-scroll>instant scroll</dfn> of a <span>scrolling box</span> <var>box</var> to
<var>position</var>, it must update the scroll position of <var>box</var> to <var>position</var>.
<p>To <dfn>scroll to the beginning of the document</dfn> for a document <var>document</var>, follow these steps:
<ol>
<li><p>Let <var>viewport</var> be the <span>viewport</span> that is associated with <var>document</var>. <!-- This assumes that there is a viewport, since
it is only invoked when navigating -->
<li><p>Let <var>position</var> be the the scroll position <var>viewport</var> would have by aligning the <span>beginning edges</span> of the
<span>scrolling area</span> with the <span>beginning edges</span> of <var>viewport</var>.
<li><p>If <var>position</var> is the same as <var>viewport</var>'s current scroll position, and <var>viewport</var> does not have an ongoing
<span title=concept-smooth-scroll>smooth scroll</span>, abort these steps.
<li><p>Let <var>task</var> be these steps:
<ol>
<li><p><span data-anolis-spec=dom title=concept-event-fire>Fire an event</span> named <code title>scroll</code> that bubbles at <var>document</var>.
</ol>
<li><p><span>Perform a scroll</span> of <var>viewport</var> to <var>position</var>, with the set of steps <var>task</var>, and <var>document</var>'s root
element as the associated element, if there is one, or null otherwise.
</ol>
<p class=note>This algorithm is used when navigating to the <code title>#top</code> fragment identifier, as defined in HTML. <span data-anolis-ref>HTML</span>
<h3>WebIDL values</h3>
<p>When asked to <dfn>normalize non-finite values</dfn> for a value <var>x</var>,
if <var>x</var> is one of the three special floating point literal values
(<code title>Infinity</code>, <code title>-Infinity</code> or <code title>NaN</code>),
then <var>x</var> must be changed to the value <code title>0</code>. <span data-anolis-ref>WEBIDL</span>
<h2>Extensions to the <code title>Window</code> Interface</h2>
<pre class=idl>enum <dfn>ScrollBehavior</dfn> { "auto", "instant", "smooth" };
dictionary <dfn>ScrollOptions</dfn> {
<span>ScrollBehavior</span> behavior = "auto";
};
dictionary <dfn>ScrollToOptions</dfn> : <span>ScrollOptions</span> {
double left;
double top;<!--
double right;
double bottom;
double blockStart;
double blockEnd;
double inlineStart;
double inlineEnd;-->
};
partial interface <span data-anolis-spec=html>Window</span> {
<span>MediaQueryList</span> <span title=dom-Window-matchMedia>matchMedia</span>(DOMString query);
[SameObject] readonly attribute <span>Screen</span> <span title=dom-Window-screen>screen</span>;
// browsing context
void <span title=dom-Window-moveTo>moveTo</span>(unrestricted double x, unrestricted double y);
void <span title=dom-Window-moveBy>moveBy</span>(unrestricted double x, unrestricted double y);
void <span title=dom-Window-resizeTo>resizeTo</span>(unrestricted double x, unrestricted double y);
void <span title=dom-Window-resizeBy>resizeBy</span>(unrestricted double x, unrestricted double y);
// viewport
readonly attribute double <span title=dom-Window-innerWidth>innerWidth</span>;
readonly attribute double <span title=dom-Window-innerHeight>innerHeight</span>;
// viewport scrolling
readonly attribute double <span title=dom-Window-scrollX>scrollX</span>;
readonly attribute double <span title=dom-Window-pageXOffset>pageXOffset</span>;
readonly attribute double <span title=dom-Window-scrollY>scrollY</span>;
readonly attribute double <span title=dom-Window-pageYOffset>pageYOffset</span>;
void <span title=dom-Window-scroll>scroll</span>(optional <span>ScrollToOptions</span> options);
void <span title=dom-Window-scroll>scroll</span>(unrestricted double x, unrestricted double y);
void <span title=dom-Window-scrollTo>scrollTo</span>(optional <span>ScrollToOptions</span> options);
void <span title=dom-Window-scrollTo>scrollTo</span>(unrestricted double x, unrestricted double y);
void <span title=dom-Window-scrollBy>scrollBy</span>(optional <span>ScrollToOptions</span> options);
void <span title=dom-Window-scrollBy>scrollBy</span>(unrestricted double x, unrestricted double y);
// client
readonly attribute double <span title=dom-Window-screenX>screenX</span>;
readonly attribute double <span title=dom-Window-screenY>screenY</span>;
readonly attribute double <span title=dom-Window-outerWidth>outerWidth</span>;
readonly attribute double <span title=dom-Window-outerHeight>outerHeight</span>;
readonly attribute double <span title=dom-Window-devicePixelRatio>devicePixelRatio</span>;
};</pre>
<p>When the <dfn title=dom-Window-matchMedia><code>matchMedia(<var>query</var>)</code></dfn> method is invoked these steps must be run:</p>
<ol>
<li><p>Let <var>parsed media query list</var> be the result of
<span title='parse a media query list' data-anolis-spec=cssom>parsing</span>
<var>query</var>.</p></li>
<li><p>Return a <em>new</em> <code>MediaQueryList</code> object,
associated with the <code data-anolis-spec=html>Window</code> object, with
<var>parsed media query list</var> as its associated
media query list.</p></li>
</ol>
<p>The <dfn title=dom-Window-screen><code>screen</code></dfn> attribute must return the <code>Screen</code> object
associated with the <code data-anolis-spec=html>Window</code> object.</p>
<p class='note'>Accessing <code title=dom-Window-screen>screen</code> through a <code data-anolis-spec=html>WindowProxy</code> object might yield different
results when the <code data-anolis-spec=dom>Document</code> is navigated.</p>
<p>The <dfn title=dom-Window-moveTo>moveTo(<var>x</var>, <var>y</var>)</dfn> method must follow these steps:
<ol>
<li><p>Optionally, terminate these steps.
<li><p><span>Normalize non-finite values</span> for <var>x</var> and <var>y</var>.
<li><p>Let <var>target</var> be the <span data-anolis-spec=html>browsing context</span> of the <span data-anolis-spec=dom>context
object</span>.
<li><p>Let <var>source</var> be the <span data-anolis-spec=html>responsible browsing context</span> of the <span data-anolis-spec=html>incumbent settings
object</span>.
<li><p>If <var>source</var> is not <span>allowed to resize and move</span> <var>target</var>, terminate these steps.
<li><p>Optionally, clamp <var>x</var> and <var>y</var> in a user-agent-defined manner so that the window does not move outside the available space.
<li><p>Move <var>target</var>'s window such that the window's top left corner is at coordinates (<var>x</var>, <var>y</var>) relative to the top left corner of
the output device, measured in CSS pixels of <var>target</var>. The positive axes are rightward and downward.
</ol>
<p>The <dfn title=dom-Window-moveBy>moveBy(<var>x</var>, <var>y</var>)</dfn> method must follow these steps:
<ol>
<li><p>Optionally, terminate these steps.
<li><p><span>Normalize non-finite values</span> for <var>x</var> and <var>y</var>.
<li><p>Let <var>target</var> be the <span data-anolis-spec=html>browsing context</span> of the <span data-anolis-spec=dom>context
object</span>.
<li><p>Let <var>source</var> be the <span data-anolis-spec=html>responsible browsing context</span> of the <span data-anolis-spec=html>incumbent settings
object</span>.
<li><p>If <var>source</var> is not <span>allowed to resize and move</span> <var>target</var>, terminate these steps.
<li><p>Optionally, clamp <var>x</var> and <var>y</var> in a user-agent-defined manner so that the window does not move outside the available space.
<li><p>Move <var>target</var>'s window <var>x</var> CSS pixels of <var>target</var> righward and <var>y</var> CSS pixels of <var>target</var> downward.
</ol>
<p>The <dfn title=dom-Window-resizeTo>resizeTo(<var>x</var>, <var>y</var>)</dfn> method must follow these steps:
<ol>
<li><p>Optionally, terminate these steps.
<li><p><span>Normalize non-finite values</span> for <var>x</var> and <var>y</var>.
<li><p>Let <var>target</var> be the <span data-anolis-spec=html>browsing context</span> of the <span data-anolis-spec=dom>context
object</span>.
<li><p>Let <var>source</var> be the <span data-anolis-spec=html>responsible browsing context</span> of the <span data-anolis-spec=html>incumbent settings
object</span>.
<li><p>If <var>source</var> is not <span>allowed to resize and move</span> <var>target</var>, terminate these steps.
<li><p>Optionally, clamp <var>x</var> and <var>y</var> in a user-agent-defined manner so that the window does not get too small or bigger than the available
space.
<li><p>Resize <var>target</var>'s window by moving its right and bottom edges such that the distance between the left and right edges of the viewport are
<var>x</var> CSS pixels of <var>target</var> and the distance between the top and bottom edges of the viewport are <var>y</var> CSS pixels of
<var>target</var>.
<li><p>Optionally, move <var>target</var>'s window in a user-agent-defined manner so that it does not grow outside the available space.
</ol>
<p>The <dfn title=dom-Window-resizeBy>resizeBy(<var>x</var>, <var>y</var>)</dfn> method must follow these steps:
<ol>
<li><p>Optionally, terminate these steps.
<li><p>Let <var>target</var> be the <span data-anolis-spec=html>browsing context</span> of the <span data-anolis-spec=dom>context
object</span>.
<li><p>Let <var>source</var> be the <span data-anolis-spec=html>responsible browsing context</span> of the <span data-anolis-spec=html>incumbent settings
object</span>.
<li><p>If <var>source</var> is not <span>allowed to resize and move</span> <var>target</var>, terminate these steps.
<li><p>Optionally, clamp <var>x</var> and <var>y</var> in a user-agent-defined manner so that the window does not get too small or bigger than the available
space.
<li><p>Resize <var>target</var>'s window by moving its right edge <var>x</var> CSS pixels of <var>target</var> righward and its bottom edge <var>y</var> CSS
pixels of <var>target</var> downward.
<li><p>Optionally, move <var>target</var>'s window in a user-agent-defined manner so that it does not grow outside the available space.
</ol>
<p>A <span data-anolis-spec=html>browsing context</span> <var>A</var> is <dfn>allowed to resize and move</dfn> a <span data-anolis-spec=html>browsing
context</span> <var>B</var> if all the following conditions are met:
<ul>
<li><p><var>B</var> is an <span data-anolis-spec=html>auxiliary browsing context</span> that was created by a script (as opposed to by an action of the user).
<li><p><var>A</var> is <span data-anolis-spec=html>familiar with</span> <var>B</var>.
</ul>
<p>The <dfn title=dom-Window-innerWidth><code>innerWidth</code></dfn> attribute must return the <span>viewport</span> width including the size of a rendered
scroll bar (if any), or zero if there is no <span>viewport</span>. <!--fingerprint--></p>
<div class='example'>
<p>The following snippet shows how to obtain the width of the viewport:</p>
<pre>var viewportWidth = innerWidth</pre>
</div>
<p>The <dfn title=dom-Window-innerHeight><code>innerHeight</code></dfn> attribute must return the <span>viewport</span> height including the size of a rendered
scroll bar (if any), or zero if there is no <span>viewport</span>. <!--fingerprint--></p>
<p>The <dfn title=dom-Window-scrollX><code>scrollX</code></dfn> attribute attribute must return the x-coordinate, relative to the <span>initial containing
block</span> origin, of the left of the <span>viewport</span>, or zero if there is no <span>viewport</span>. <!--fingerprint--></p>
<p>The <dfn title=dom-Window-pageXOffset><code>pageXOffset</code></dfn> attribute must return the value returned by the
<code title=dom-Window-scrollX>scrollX</code> attribute.</p>
<p>The <dfn title=dom-Window-scrollY><code>scrollY</code></dfn> attribute attribute must return the y-coordinate, relative to the <span>initial containing
block</span> origin, of the top of the <span>viewport</span>, or zero if there is no <span>viewport</span>. <!--fingerprint--></p>
<p>The <dfn title=dom-Window-pageYOffset><code>pageYOffset</code></dfn> attribute must return the value returned by the
<code title=dom-Window-scrollY>scrollY</code> attribute.</p>
<p>When the <dfn title=dom-Window-scroll><code>scroll()</code></dfn> method is invoked these
steps must be run:</p>
<ol>
<li><p>If invoked with one argument, follow these substeps:
<ol>
<li><p>Let <var>options</var> be the argument.
<li><p>Let <var>x</var> be the value of the <code title>left</code> dictionary member of <var>options</var>, if present, or the <span>viewport</span>'s current scroll position on the x axis otherwise.
<li><p>Let <var>y</var> be the value of the <code title>top</code> dictionary member of <var>options</var>, if present, or the <span>viewport</span>'s current scroll position on the y axis otherwise.
</ol>
<li><p>If invoked with two arguments, follow these substeps:
<ol>
<li><p>Let <var>options</var> be null <span title="converted to an IDL value">converted</span> to a <code>ScrollToOptions</code> dictionary. <span data-anolis-ref>WEBIDL</span>
<li><p>Let <var>x</var> and <var>y</var> be the arguments, respectively.
<li><p><span>Normalize non-finite values</span> for <var>x</var> and <var>y</var>.
</ol>
<li><p>If there is no <span>viewport</span>, abort these steps.
<li><p>Let <var>viewport width</var> be the width of the <span>viewport</span> excluding the width of the scroll bar, if any.
<li><p>Let <var>viewport height</var> be the height of the <span>viewport</span> excluding the height of the scroll bar, if any.
<li>
<dl class=switch>
<dt>If the <span>viewport</span> has rightward <span title="overflow directions">overflow direction</span>
<dd><p>Let <var>x</var> be max(0, min(<var>x</var>,
<span>viewport</span> <span>scrolling area</span> width - <var>viewport width</var>)).</p></dd>
<dt>If the <span>viewport</span> has leftward <span title="overflow directions">overflow direction</span>
<dd><p>Let <var>x</var> be min(0, max(<var>x</var>,
<var>viewport width</var> - <span>viewport</span> <span>scrolling area</span>
width)).</p></dd>
</dl>
<li>
<dl class=switch>
<dt>If the <span>viewport</span> has downward <span title="overflow directions">overflow direction</span>
<dd><p>Let <var>y</var> be max(0, min(<var>y</var>,
<span>viewport</span> <span>scrolling area</span> height - <var>viewport height</var>)).</p></dd>
<dt>If the <span>viewport</span> has upward <span title="overflow directions">overflow direction</span>
<dd><p>Let <var>y</var> be min(0, max(<var>y</var>,
<var>viewport height</var> - <span>viewport</span> <span>scrolling area</span>
height)).</p></dd>
</dl>
<li><p>Let <var>position</var> be the scroll position the <span>viewport</span> would have by aligning the x-coordinate <var>x</var> of the
<span>viewport</span> <span>scrolling area</span> with the left of the <span>viewport</span> and aligning the y-coordinate <var>y</var> of the
<span>viewport</span> <span>scrolling area</span> with the top of the <span>viewport</span>.
<li><p>If <var>position</var> is the same as the <span>viewport</span>'s current scroll position, and the <span>viewport</span> does not have an ongoing
<span title=concept-smooth-scroll>smooth scroll</span>, abort these steps.
<li><p>Let <var>task</var> be these steps:
<ol>
<li><p><span data-anolis-spec=dom title=concept-event-fire>Fire an event</span> named <code title>scroll</code> that bubbles at the
<code data-anolis-spec=dom>Document</code> object.
</ol>
<li><p><span>Perform a scroll</span> of the <span>viewport</span> to <var>position</var>, with the set of steps <var>task</var>, and the
<code data-anolis-spec=dom>Document</code>'s root element as the associated element, if there is one, or null otherwise, and the scroll behavior being the
value of the <code title>behavior</code> dictionary member of <var>options</var>.
</ol>
<p>When the <dfn title=dom-Window-scrollTo><code>scrollTo()</code></dfn> method is invoked, the
user agent must act as if the <code title=dom-Window-scroll>scroll()</code> method was invoked with the same arguments.</p>
<p>When the <dfn title=dom-Window-scrollBy><code>scrollBy()</code></dfn> method is invoked, the
user agent must act as if the <code title=dom-Window-scroll>scroll()</code> method was invoked with
<var>x</var> plus <code title='dom-Window-scrollX'>scrollX</code>
as first argument and <var>y</var> plus
<code title='dom-Window-scrollY'>scrollY</code> as second argument.</p>
<p>The <dfn title=dom-Window-screenX><code>screenX</code></dfn> attribute must return the x-coordinate,
relative to the origin of the screen of the output device, of the left of
the client window as number of pixels, or zero if there is no such
thing. <!--fingerprint--></p>
<p>The <dfn title=dom-Window-screenY><code>screenY</code></dfn> attribute must return the y-coordinate,
relative to the origin of the screen of the output device, of the top of
the client window as number of pixels, or zero if there is no such
thing. <!--fingerprint--></p>
<p>The <dfn title=dom-Window-outerWidth><code>outerWidth</code></dfn> attribute must return the width of the
client window. If there is no client window this
attribute must return zero. <!--fingerprint--></p>
<p>The <dfn title=dom-Window-outerHeight><code>outerHeight</code></dfn> attribute must return the height of the
client window. If there is no client window this
attribute must return zero. <!--fingerprint--></p>
<p>The <dfn title=dom-Window-devicePixelRatio><code>devicePixelRatio</code></dfn> attribute must return the result of the following algorithm:
<ol>
<li><p>If there is no output device, return 1 and abort these steps.
<li><p>Let <var>CSS pixel size</var> be the size of a CSS pixel at the current <span>page zoom</span> scale factor and at a <span>pinch zoom</span> scale
factor of 1.0.
<li><p>Let <var>device pixel size</var> be the vertical size of a device pixel of the output device.
<li><p>Return the result of dividing <var>CSS pixel size</var> by <var>device pixel size</var>.
</ol>
<h4>The <var>features</var> argument to the <code title>open()</code> method</h4>
<p>HTML defines the <code data-anolis-spec=html title=dom-open>open()</code> method but has no defined effect for the third argument, <var>features</var>.
<span data-anolis-ref>HTML</span>
<p>This specification defines the effect of the <var>features</var> argument for user agents that do not opt to ignore it, as follows:
<ol>
<li><p>If the method does not result in a new <span data-anolis-spec=html>auxiliary browsing context</span> being created, terminate these steps.
<li><p>Let <var>target</var> be the new <span data-anolis-spec=html>auxiliary browsing context</span>.
<li><p>Let <var>tokens</var> be the result of <span data-anolis-spec=html title="split a string on commas">splitting <var>features</var> on commas</span>.
<li><p>Let <var>parsed features</var> be a new empty dictionary.
<li><p><i>Token loop</i>: For each token <var>token</var> in <var>tokens</var>, follow these substeps:
<ol>
<li><p>Let <var>input</var> be <var>token</var>.
<li><p>Let <var>position</var> point at the first character of <var>input</var>.
<li><p><span data-anolis-spec=html>Skip whitespace</span>.
<li><p><span data-anolis-spec=html>Collect a sequence of characters</span> that are not <span data-anolis-spec=html title="space character">space
characters</span> nor "<code title>=</code>" (U+003D). Let <var>name</var> be the collected characters, <span data-anolis-spec=dom>converted to ASCII
lowercase</span>.
<li><p>If <var>name</var> is in <var>parsed features</var> or if <var>name</var> is not a <span>supported <code title>open()</code> feature name</span>,
continue <i>token loop</i>.
<li><p><span data-anolis-spec=html>Skip whitespace</span>.
<li><p>If the character at <var>position</var> is not "<code title>=</code>" (U+003D), continue <i>token loop</i>.
<li><p>Advance <var>position</var> by one.
<li><p>If <var>position</var> is past the end of <var>input</var>, continue <i>token loop</i>.
<li><p><span data-anolis-spec=html>Collect a sequence of characters</span> that are any characters. Let <var>raw value</var> be the collected characters.
<li><p>Let <var>value</var> be the result of invoking the <span data-anolis-spec=html>rules for parsing integers</span> on <var>raw value</var>.
<li><p>If <var>value</var> is an error, continue <i>token loop</i>.
<li><p>Set <var>name</var> in <var>parsed features</var> to <var>value</var>.
</ol>
<li><p>If <code title=dom-open-features-left>left</code> is present in <var>parsed features</var>, follow these substeps:
<ol>
<li><p>Let <var>x</var> be the value of <code title=dom-open-features-left>left</code>.
<li><p>Optionally, clamp <var>x</var> in a user-agent-defined manner so that the window does not move outside the available space.
<li><p>Optionally, move <var>target</var>'s window such that the window's left edge is at the horizontal coordinate <var>x</var> relative to the left edge of
the output device, measured in CSS pixels of <var>target</var>. The positive axis is rightward.
</ol>
<li><p>If <code title=dom-open-features-top>top</code> is present in <var>parsed features</var>, follow these substeps:
<ol>
<li><p>Let <var>y</var> be the value of <code title=dom-open-features-top>top</code>.
<li><p>Optionally, clamp <var>y</var> in a user-agent-defined manner so that the window does not move outside the available space.
<li><p>Optionally, move <var>target</var>'s window such that the window's top edge is at the vertical coordinate <var>y</var> relative to the top edge of
the output device, measured in CSS pixels of <var>target</var>. The positive axis is downward.
</ol>
<li><p>If <code title=dom-open-features-width>width</code> is present in <var>parsed features</var>, follow these substeps:
<ol>
<li><p>Let <var>x</var> be the value of <code title=dom-open-features-width>width</code>.
<li><p>Optionally, clamp <var>x</var> in a user-agent-defined manner so that the window does not get too small or bigger than the available space.
<li><p>Optionally, size <var>target</var>'s window by moving its right edge such that the distance between the left and right edges of the viewport are
<var>x</var> CSS pixels of <var>target</var>.
<li><p>Optionally, move <var>target</var>'s window in a user-agent-defined manner so that it does not grow outside the available space.
</ol>
<li><p>If <code title=dom-open-features-height>height</code> is present in <var>parsed features</var>, follow these substeps:
<ol>
<li><p>Let <var>y</var> be the value of <code title=dom-open-features-height>height</code>.
<li><p>Optionally, clamp <var>y</var> in a user-agent-defined manner so that the window does not get too small or bigger than the available space.
<li><p>Optionally, size <var>target</var>'s window by moving its bottom edge such that the distance between the top and bottom edges of the viewport are
<var>y</var> CSS pixels of <var>target</var>.
<li><p>Optionally, move <var>target</var>'s window in a user-agent-defined manner so that it does not grow outside the available space.
</ol>
</ol>
<p>A <dfn>supported <code title>open()</code> feature name</dfn> is one of the following:
<dl>
<dt><dfn title=dom-open-features-width>width</dfn>
<dd><p>The width of the viewport.
<dt><dfn title=dom-open-features-height>height</dfn>
<dd><p>The height of the viewport.
<dt><dfn title=dom-open-features-left>left</dfn>
<dd><p>The left position of the window.
<dt><dfn title=dom-open-features-top>top</dfn>
<dd><p>The top position of the window.
</dl>
<h3>The <code title>MediaQueryList</code> Interface</h3>
<p>A <code>MediaQueryList</code> object has an associated media query list set on creation.</p>
<p>A <code>MediaQueryList</code> object has an associated <dfn title=concept-MediaQueryList-media>media</dfn> which is the
<span title='serialize a media query list' data-anolis-spec=cssom>serialized</span> form of the associated media query list.</p>
<p>A <code>MediaQueryList</code> object has an associated <dfn title=concept-MediaQueryList-matches>matches state</dfn> which is
true if the associated media query list matches the state of the rendered <code data-anolis-spec=dom>Document</code>, and false otherwise.</p>
<p>If the associated media query list changes in evaluation, the user agent must <span data-anolis-spec=html>queue a task</span> to run these steps:</p>
<ol>
<li><p>Let <var>target</var> be the <code>MediaQueryList</code> object.</p></li>
<li><p>Let <var>event</var> be a new <span data-anolis-spec=dom title=concept-event>event</span>
using the <code>MediaQueryListEvent</code> interface,
with its <code data-anolis-spec=dom title=dom-Event-type>type</code> attribute initialized to <code title>change</code>,
its <code data-anolis-spec=dom title=dom-Event-isTrusted>isTrusted</code> attribute initialized to true,
its <code title=dom-MediaQueryListEvent-media>media</code> attribute initialized to <var>target</var>'s <span title=concept-MediaQueryList-media>media</span>,
and its <code title=dom-MediaQueryListEvent-matches>matches</code> attribute initialized to <var>target</var>'s <span title=concept-MediaQueryList-matches>matches state</span>. <!--fingerprint--></p></li>
<li><p><span data-anolis-spec=dom title=concept-event-dispatch>Dispatch</span> <var>event</var> to <var>target</var>.</p></li>
</ol>
<div class='example'>
<p>A simple piece of code that detects changes in the orientation of the viewport can be written as follows:</p>
<pre>function handleOrientationChange(event) {
if(event.matches) // landscape
…
else
…
}
var mql = matchMedia("(orientation:landscape)")
mql.onchange = handleOrientationChange</pre>
</div>
<pre class=idl>interface <dfn>MediaQueryList</dfn> : <span data-anolis-spec=dom>EventTarget</span> {
readonly attribute DOMString <span title=dom-MediaQueryList-media>media</span>;
readonly attribute boolean <span title=dom-MediaQueryList-matches>matches</span>;
void <span title=dom-MediaQueryList-addListener>addListener</span>(<span data-anolis-spec=dom>EventListener</span>? listener);
void <span title=dom-MediaQueryList-removeListener>removeListener</span>(<span data-anolis-spec=dom>EventListener</span>? listener);
attribute <span data-anolis-spec=html>EventHandler</span> onchange;
};</pre>
<p>The <dfn title=dom-MediaQueryList-media><code>media</code></dfn> attribute must return
the associated <span title=concept-MediaQueryList-media>media</span>.</p>
<p>The <dfn title=dom-MediaQueryList-matches><code>matches</code></dfn> attribute must return
the associated <span title=concept-MediaQueryList-matches>matches state</span>. <!--fingerprint--></p>
<p>The <dfn title=dom-MediaQueryList-addListener><code>addListener(<var>listener</var>)</code></dfn> method must run these steps:</p>
<ol>
<li><p>If <var title="">listener</var> is null, terminate these steps.
<li><p>Append an <span data-anolis-spec=dom title="concept-event-listener">event listener</span>
to the associated list of
<span data-anolis-spec=dom title="concept-event-listener">event listeners</span> with <b>type</b>
set to <code title>change</code>, <b>callback</b> set to <var title="">listener</var>, and
<b>capture</b> set to false, unless there
already is an <span data-anolis-spec=dom title="concept-event-listener">event listener</span> in
that list with the same <b>type</b>, <b>callback</b>, and <b>capture</b>.
</ol>
<p>The <dfn title=dom-MediaQueryList-removeListener><code>removeListener(<var>listener</var>)</code></dfn> method must run these steps:</p>
<ol>
<li><p>Remove an <span data-anolis-spec=dom title="concept-event-listener">event listener</span>
from the associated list of
<span data-anolis-spec=dom title="concept-event-listener">event listeners</span>, whose
<b>type</b> is <code title>change</code>, <b>callback</b> is <var title="">listener</var>, and
<b>capture</b> is false.</p>
</ol>
<p class=note>This specification initially had a custom callback mechanism with <code title=dom-MediaQueryList-addListener>addListener</code> and
<code title=dom-MediaQueryList-removeListener>removeListener</code>, and the callback was invoked with the associated media query list as argument.
Now the normal event mechanism is used instead.
For backwards compatibility, the <code title=dom-MediaQueryList-addListener>addListener</code> and <code title=dom-MediaQueryList-removeListener>removeListener</code> methods
are basically aliases for <code data-anolis-spec=dom title=dom-EventTarget-addEventListener>addEventListener</code> and <code data-anolis-spec=dom title=dom-EventTarget-removeEventListener>removeEventListener</code>, respectively,
and the <code title>change</code> event masquerades as a <code>MediaQueryList</code>.</p>
<p>The following are the <span data-anolis-spec=html>event handlers</span>
(and their corresponding <span data-anolis-spec=html title="event handler event type">event handler event types</span>) that must be supported,
as <span data-anolis-spec=html>event handler IDL attributes</span>, by all objects implementing the <code>MediaQueryList</code> interface:</p>
<table class="complex data">
<thead>
<tr>
<th><span data-anolis-spec=html title="event handlers">Event handler</span></th>
<th><span data-anolis-spec=html>Event handler event type</span></th>
</tr>
</thead>
<tbody>
<tr>
<td><dfn title=handler-MediaQueryList-onchange>onchange</dfn>
<td><code title>change</code>
</tr>
</tbody>
</table>
<pre class=idl>[<span data-anolis-spec=dom title=concept-event-constructor>Constructor</span>(DOMString type, optional <span>MediaQueryListEventInit</span> eventInitDict)]
interface <dfn>MediaQueryListEvent</dfn> : <span data-anolis-spec=dom>Event</span> {
readonly attribute DOMString <span title=dom-MediaQueryListEvent-media>media</span>;
readonly attribute boolean <span title=dom-MediaQueryListEvent-matches>matches</span>;
};
dictionary <dfn>MediaQueryListEventInit</dfn> : <span data-anolis-spec=dom>EventInit</span> {
DOMString media = "";
boolean matches = false;
};</pre>
<p>The <dfn title=dom-MediaQueryListEvent-media><code>media</code></dfn> attribute must return the value it was initialized to.</p>
<p>The <dfn title=dom-MediaQueryListEvent-matches><code>matches</code></dfn> attribute must return the value it was initialized to.</p>
<h3>The <code title>Screen</code> Interface</h3>
<p>As its name suggests, the <code>Screen</code> interface represents information about the screen of the output device.</p>
<pre class=idl>interface <dfn>Screen</dfn> {
readonly attribute double <span title=dom-Screen-availWidth>availWidth</span>;
readonly attribute double <span title=dom-Screen-availHeight>availHeight</span>;
readonly attribute double <span title=dom-Screen-width>width</span>;
readonly attribute double <span title=dom-Screen-height>height</span>;
readonly attribute unsigned long <span title=dom-Screen-colorDepth>colorDepth</span>;
readonly attribute unsigned long <span title=dom-Screen-pixelDepth>pixelDepth</span>;
};</pre>
<p>The <dfn title=dom-Screen-availWidth><code>availWidth</code></dfn> attribute must return the available width of the rendering surface of the output device,
in CSS pixels. <!--fingerprint--></p>
<p>The <dfn title=dom-Screen-availHeight><code>availHeight</code></dfn> attribute must return the available height of the rendering surface of the output
device, in CSS pixels. <!--fingerprint--></p>
<p>The <dfn title=dom-Screen-width><code>width</code></dfn> attribute must return the width of the output device, in CSS pixels. <!--fingerprint--></p>
<p>The <dfn title=dom-Screen-height><code>height</code></dfn> attribute must return the height of the output device, in CSS pixels. <!--fingerprint--></p>
<p>The <dfn title=dom-Screen-colorDepth><code>colorDepth</code></dfn> attribute must return 24.</p>
<p>The <dfn title=dom-Screen-pixelDepth><code>pixelDepth</code></dfn> attribute must return 24.</p>
<p class=note>The <code title=dom-Screen-colorDepth>colorDepth</code> and <code title=dom-Screen-pixelDepth>pixelDepth</code> attributes are useless but are
included for compatibility.
<h2>Extensions to the <code title>Document</code> Interface</h2>
<pre class=idl>partial interface <span data-anolis-spec=dom>Document</span> {
<span data-anolis-spec=dom>Element</span>? <span title=dom-Document-elementFromPoint>elementFromPoint</span>(double x, double y);
sequence<<span data-anolis-spec=dom>Element</span>> <span title=dom-Document-elementsFromPoint>elementsFromPoint</span>(double x, double y);
<span>CaretPosition</span>? <span title=dom-Document-caretPositionFromPoint>caretPositionFromPoint</span>(double x, double y);
};</pre>
<p>The <dfn title=dom-Document-elementFromPoint><code>elementFromPoint(<var>x</var>, <var>y</var>)</code></dfn> method must follow these steps:
<ol>
<li><p>If either argument is negative, <var>x</var> is greater than the <span>viewport</span> width excluding the size of a rendered scroll bar (if any), or
<var>y</var> is greater than the <span>viewport</span> height excluding the size of a rendered scroll bar (if any), or there is no <span>viewport</span>
associated with the document, return null and terminate these steps.
<li><p>If there is a <span>layout box</span> in the <span>viewport</span> that would be a target for hit testing at coordinates <var>x</var>,<var>y</var>,
when applying the <span>transforms</span> that apply to the descendants of the <span>viewport</span>, return the associated element and terminate these steps.
<li><p>If the document has a root element, return the root element and terminate these steps.
<li><p>Return null.
</ol>
<p class=note>The <code title=dom-Document-elementFromPoint>elementFromPoint()</code> method does not necessarily return the top-most painted element. For
instance, an element can be excluded from being a target for hit testing by using the 'pointer-events' CSS property.
<p class=atrisk>The <dfn title=dom-Document-elementsFromPoint><code>elementsFromPoint(<var>x</var>, <var>y</var>)</code></dfn> method must follow these steps:
<ol>
<li><p>Let <var>sequence</var> be a new empty sequence.
<li><p>If either argument is negative, <var>x</var> is greater than the <span>viewport</span> width excluding the size of a rendered scroll bar (if any), or
<var>y</var> is greater than the <span>viewport</span> height excluding the size of a rendered scroll bar (if any), or there is no <span>viewport</span>
associated with the document, return <var>sequence</var> and terminate these steps.
<li><p>For each <span>layout box</span> in the <span>viewport</span>, in paint order, starting with the topmost box, that would be a target for hit testing at
coordinates <var>x</var>,<var>y</var> even if nothing would be overlapping it, when applying the <span>transforms</span> that apply to the descendants of the
<span>viewport</span>, append the associated element to <var>sequence</var>.
<li><p>If the document has a root element, and the last item in <var>sequence</var> is not the root element, append the root element to <var>sequence</var>.
<li><p>Return <var>sequence</var>.
</ol>