csswg-drafts/cssom-view/Overview.html at c68aeb3df2803f49343081ac0f2b61de4c5f2178 · w3c/csswg-drafts · GitHub

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<!DOCTYPE html><html lang="en-US"><head>
  <meta charset="utf-8">
  <title>CSSOM View Module</title>
  <link href="cssom.css" rel="stylesheet">
  <link href="https://www.w3.org/StyleSheets/TR/W3C-ED" rel="stylesheet">
 </head>
 <body class="draft">
  <div class="head">

<!--begin-logo-->
<p><a href="http://www.w3.org/"><img alt="W3C" height="48" src="http://www.w3.org/Icons/w3c_home" width="72"></a></p>
<!--end-logo-->

   <h1 id="cssom-view-module">CSSOM View Module</h1>

   <h2 class="no-num no-toc" id="w3c-doctype">Editor's Draft 26 April 2013</h2>

   <dl>

    <dt>This Version:</dt>
    <dd class="dontpublish"><a href="https://dvcs.w3.org/hg/csswg/raw-file/tip/cssom-view/Overview.html">https://dvcs.w3.org/hg/csswg/raw-file/tip/cssom-view/Overview.html</a></dd>
    <dt class="dontpublish">Participate:</dt>
    <dd class="dontpublish"><a href="mailto:www-style@w3.org?subject==%5Bcssom%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&amp;component=CSSOM%20View">File a bug</a> (<a href="https://www.w3.org/Bugs/Public/buglist.cgi?component=CSSOM%20View&amp;product=CSS&amp;resolution=---">open bugs</a>) <script async="" src="https://w3c-test.org/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="dontpublish">Previous Versions:</dt>
    <dd class="dontpublish"><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 class="dontpublish"><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 class="dontpublish"><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><a href="http://www.w3.org/wiki/User:Gadams">Glenn Adams</a>
    (<a href="http://www.cox.com/">Cox Communications, Inc.</a>)
    &lt;<a href="mailto:glenn.adams@cox.com">glenn.adams@cox.com</a>&gt;</dd>
    <dd><a>Simon Pieters</a>
    (<a href="http://www.opera.com/">Opera Software ASA</a>)
    &lt;<a href="mailto:simponp@opera.com">simonp@opera.com</a>&gt;</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>)
    &lt;<a href="mailto:annevk@opera.com">annevk@opera.com</a>&gt;</dd>
   </dl>


<!--begin-copyright-->
<p class="copyright"><a href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">Copyright</a> © 2013 <a href="http://www.w3.org/"><abbr title="World Wide Web Consortium">W3C</abbr></a><sup>®</sup> (<a href="http://www.csail.mit.edu/"><abbr title="Massachusetts Institute of Technology">MIT</abbr></a>, <a href="http://www.ercim.eu/"><abbr title="European Research Consortium for Informatics and Mathematics">ERCIM</abbr></a>, <a href="http://www.keio.ac.jp/">Keio</a>, <a href="http://ev.buaa.edu.cn/">Beihang</a>), All Rights Reserved. W3C <a href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>, <a href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a> and <a href="http://www.w3.org/Consortium/Legal/copyright-documents">document use</a> rules apply.</p>
<!--end-copyright-->

  </div>

  <hr>

  <h2 class="no-num no-toc" id="abstract">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 class="no-num no-toc" id="sotd">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 26 April 2013 Editor's Draft 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 class="no-num no-toc" id="toc">Table of Contents</h2>


<!--begin-toc-->
<ol class="toc">
 <li><a href="#background"><span class="secno">1 </span>Background</a></li>
 <li><a href="#conformance"><span class="secno">2 </span>Conformance</a>
  <ol class="toc">
   <li><a href="#webidl"><span class="secno">2.1 </span>Web IDL</a></ol></li>
 <li><a href="#terminology"><span class="secno">3 </span>Terminology</a>
  <ol class="toc">
   <li><a href="#css-pixels"><span class="secno">3.1 </span>CSS pixels</a></ol></li>
 <li><a href="#extensions-to-the-window-interface"><span class="secno">4 </span>Extensions to the <code title="">Window</code> Interface</a>
  <ol class="toc">
   <li><a href="#the-mediaquerylist-interface"><span class="secno">4.1 </span>The <code title="">MediaQueryList</code> Interface</a></li>
   <li><a href="#the-screen-interface"><span class="secno">4.2 </span>The <code title="">Screen</code> Interface</a></ol></li>
 <li><a href="#extensions-to-the-document-interface"><span class="secno">5 </span>Extensions to the <code title="">Document</code> Interface</a>
  <ol class="toc">
   <li><a href="#the-caretposition-interface"><span class="secno">5.1 </span>The <code title="">CaretPosition</code> Interface</a></ol></li>
 <li><a href="#extensions-to-the-element-interface"><span class="secno">6 </span>Extensions to the <code title="">Element</code> Interface</a>
  <ol class="toc">
   <li><a href="#the-getclientrects-and-getboundingclientrect-methods"><span class="secno">6.1 </span>The <code title="">getClientRects()</code> and
  <code title="">getBoundingClientRect()</code> methods</a></li>
   <li><a href="#element-scrolling-members"><span class="secno">6.2 </span><code title="">Element</code> Scrolling Members</a></li>
   <li><a href="#client-attributes"><span class="secno">6.3 </span>The <code title="">clientTop</code>,
  <code title="">clientLeft</code>, <code title="">clientWidth</code>, and
  <code title="">clientHeight</code> attributes</a></ol></li>
 <li><a href="#extensions-to-the-htmlelement-interface"><span class="secno">7 </span>Extensions to the <code title="">HTMLElement</code> Interface</a></li>
 <li><a href="#extensions-to-the-range-interface"><span class="secno">8 </span>Extensions to the <code title="">Range</code> Interface</a></li>
 <li><a href="#extensions-to-the-mouseevent-interface"><span class="secno">9 </span>Extensions to the <code title="">MouseEvent</code> Interface</a></li>
 <li><a href="#rectangles"><span class="secno">10 </span>Rectangles</a>
  <ol class="toc">
   <li><a href="#the-clientrectlist-interface"><span class="secno">10.1 </span>The <code title="">ClientRectList</code> Interface</a></li>
   <li><a href="#the-clientrect-interface"><span class="secno">10.2 </span>The <code title="">ClientRect</code> Interface</a></ol></li>
 <li><a class="no-num" href="#references">References</a>
  <ol class="toc">
   <li><a class="no-num" href="#normative-references">Normative references</a></ol></li>
 <li><a class="no-num" href="#acknowledgments">Acknowledgments</a></ol>
<!--end-toc-->


  <h2 id="background"><span class="secno">1 </span>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 id="conformance"><span class="secno">2 </span>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. <a href="#refsRFC2119">[RFC2119]</a>

<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.

  <p>A conforming user agent implements all the requirements made by this
  specification.</p>


  <h3 id="webidl"><span class="secno">2.1 </span>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. <a href="#refsWEBIDL">[WEBIDL]</a>


  <h2 id="terminology"><span class="secno">3 </span>Terminology</h2>

  <p>Terminology used in this specification is from
  DOM Core,
  CSSOM and
  HTML.
  <a href="#refsDOM">[DOM]</a>
  <a href="#refsCSSOM">[CSSOM]</a>
  <a href="#refsHTML">[HTML]</a>

  <p class="issue"><dfn id="mouseevent"><code>MouseEvent</code></dfn> is defined in …

  <p><dfn id="the-html-body-element">The HTML <code>body</code> element</dfn> is the first
  <code>body</code>
  <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/infrastructure.html#html-elements" title="HTML elements">HTML element</a> child of the root
  <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/infrastructure.html#html-elements" title="HTML elements">HTML element</a> <code>html</code>.</p>

  <p><dfn id="content-edge">Content edge</dfn>,
  <dfn id="padding-edge">padding edge</dfn>,
  <dfn id="border-edge">border edge</dfn>, and
  <dfn id="canvas">canvas</dfn> are defined by CSS.
  <!--<span data-anolis-ref>CSS</span>-->

  <p><dfn id="viewport">Viewport</dfn> and
  <dfn id="initial-containing-block">initial containing block</dfn> are
  defined by CSS 2.1 unless there is an ancestor <code>foreignObject</code>
  element in the <code>http://www.w3.org/2000/svg</code> namespace in which
  case that element acts as viewport and initial containing block.
  <!--<span data-anolis-ref>CSS</span>-->

  <p>The term <dfn id="content">content</dfn> refers to the dimensions of the element's
  content area, including overflown content.
  <!--<span data-anolis-ref>CSS</span>-->

  <p>The term <dfn id="document-content">document content</dfn> refers to the area on the
  <a href="#canvas">canvas</a> that is rendered upon, excluding content on negative
  axis.</p>

  <p>The term <dfn id="css-layout-box">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
  '<code title="">display</code>' property that is <code>table-column</code> or
  <code>table-column-group</code> must be considered to have an associated <a href="#css-layout-box">CSS
  layout box</a> (the column or column group, respectively).</p>

  <h3 id="css-pixels"><span class="secno">3.1 </span>CSS pixels</h3>

  <p>All coordinates and dimensions for the APIs defined in this
  specification are in CSS pixels. <!--<span data-anolis-ref>CSS</span>-->

  <p class="note">This does not apply to e.g.
  <code title="widl-Window-matchMedia">matchMedia()</code> as the units
  are explicitly given there.</p>


  <h2 id="extensions-to-the-window-interface"><span class="secno">4 </span>Extensions to the <code title="">Window</code> Interface</h2>


<pre class="idl"><span class="idlInterface" id="widl-def-Window">partial interface <span class="idlInterfaceID">Window</span> {
<span class="idlMethod">    <span class="idlMethType"><a>MediaQueryList</a></span> <span class="idlMethName"><a href="#widl-Window-matchMedia-MediaQueryList-DOMString-query">matchMedia</a></span> (<span class="idlParam"><span class="idlParamType"><a>DOMString</a></span> <span class="idlParamName">query</span></span>);</span>
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>Screen</a></span> <span class="idlAttrName"><a href="#widl-Window-screen">screen</a></span>;</span>
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>long</a></span> <span class="idlAttrName"><a href="#widl-Window-innerWidth">innerWidth</a></span>;</span>
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>long</a></span> <span class="idlAttrName"><a href="#widl-Window-innerHeight">innerHeight</a></span>;</span>
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>long</a></span> <span class="idlAttrName"><a href="#widl-Window-scrollX">scrollX</a></span>;</span>
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>long</a></span> <span class="idlAttrName"><a href="#widl-Window-pageXOffset">pageXOffset</a></span>;</span>
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>long</a></span> <span class="idlAttrName"><a href="#widl-Window-scrollY">scrollY</a></span>;</span>
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>long</a></span> <span class="idlAttrName"><a href="#widl-Window-pageYOffset">pageYOffset</a></span>;</span>
<span class="idlMethod">    <span class="idlMethType"><a>void</a></span> <span class="idlMethName"><a href="#widl-Window-scroll-void-long-x-long-y">scroll</a></span> (<span class="idlParam"><span class="idlParamType"><a>long</a></span> <a class="idlParamName" href="#widl-MouseEvent-x">x</a></span>, <span class="idlParam"><span class="idlParamType"><a>long</a></span> <a class="idlParamName" href="#widl-MouseEvent-y">y</a></span>);</span>
<span class="idlMethod">    <span class="idlMethType"><a>void</a></span> <span class="idlMethName"><a href="#widl-Window-scrollTo-void-long-x-long-y">scrollTo</a></span> (<span class="idlParam"><span class="idlParamType"><a>long</a></span> <a class="idlParamName" href="#widl-MouseEvent-x">x</a></span>, <span class="idlParam"><span class="idlParamType"><a>long</a></span> <a class="idlParamName" href="#widl-MouseEvent-y">y</a></span>);</span>
<span class="idlMethod">    <span class="idlMethType"><a>void</a></span> <span class="idlMethName"><a href="#widl-Window-scrollBy-void-long-x-long-y">scrollBy</a></span> (<span class="idlParam"><span class="idlParamType"><a>long</a></span> <a class="idlParamName" href="#widl-MouseEvent-x">x</a></span>, <span class="idlParam"><span class="idlParamType"><a>long</a></span> <a class="idlParamName" href="#widl-MouseEvent-y">y</a></span>);</span>
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>long</a></span> <span class="idlAttrName"><a href="#widl-Window-screenX">screenX</a></span>;</span>
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>long</a></span> <span class="idlAttrName"><a href="#widl-Window-screenY">screenY</a></span>;</span>
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>long</a></span> <span class="idlAttrName"><a href="#widl-Window-outerWidth">outerWidth</a></span>;</span>
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>long</a></span> <span class="idlAttrName"><a href="#widl-Window-outerHeight">outerHeight</a></span>;</span>
};</span></pre>
<dl class="attributes">
<dt class="attribute" id="widl-Window-screen">
<dfn id="widl-Window-screen"><code>screen</code></dfn> of type <span class="idlAttrType"><a>Screen</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-Window-screen">screen</a></code> attribute  must return the <code><a href="#widl-Window-screen">screen</a></code> object    associated with the <code class="external"><a href="http://www.whatwg.org/specs/web-apps/current-work/multipage/browsers.html#window">Window</a></code> object. It always returns the same    object.</p>    <p class="note">Accessing <code><a href="#widl-Window-screen">screen</a></code> through a <code class="external"><a href="http://www.whatwg.org/specs/web-apps/current-work/multipage/browsers.html#windowproxy">WindowProxy</a></code> object might yield different results    when the <code class="external"><a href="http://dom.spec.whatwg.org/#document">Document</a></code> is navigated.</dd>
<dt class="attribute" id="widl-Window-innerWidth">
<dfn id="widl-Window-innerWidth"><code>innerWidth</code></dfn> of type <span class="idlAttrType"><a>long</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-Window-innerWidth">innerWidth</a></code> attribute must return the <a href="#viewport">viewport</a> width including the size of a rendered scroll bar (if any).</p>    <div class="example">     <p>The following snippet shows how to obtain the width of the viewport:</p>     <pre><code>var viewportWidth = innerWidth</code></pre>    </div></dd>
<dt class="attribute" id="widl-Window-innerHeight">
<dfn id="widl-Window-innerHeight"><code>innerHeight</code></dfn> of type <span class="idlAttrType"><a>long</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-Window-innerHeight">innerHeight</a></code> attribute must return the <a href="#viewport">viewport</a> height including the size of a rendered scroll bar (if any).</dd>
<dt class="attribute" id="widl-Window-scrollX">
<dfn id="widl-Window-scrollX"><code>scrollX</code></dfn> of type <span class="idlAttrType"><a>long</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-Window-scrollX">scrollX</a></code> attribute attribute must return the x-coordinate, relative to the <a href="#initial-containing-block">initial containing block</a> origin, of the left of the <a href="#viewport">viewport</a>.</dd>
<dt class="attribute" id="widl-Window-pageXOffset">
<dfn id="widl-Window-pageXOffset"><code>pageXOffset</code></dfn> of type <span class="idlAttrType"><a>long</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-Window-pageXOffset">pageXOffset</a></code> attribute attribute must return the value returned by the <code><a href="#widl-Window-scrollX">scrollX</a></code> attribute.</dd>
<dt class="attribute" id="widl-Window-scrollY">
<dfn id="widl-Window-scrollY"><code>scrollY</code></dfn> of type <span class="idlAttrType"><a>long</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-Window-scrollY">scrollY</a></code> attribute attribute must return the y-coordinate, relative to the <a href="#initial-containing-block">initial containing block</a> origin, of the top of the <a href="#viewport">viewport</a>.</dd>
<dt class="attribute" id="widl-Window-pageYOffset">
<dfn id="widl-Window-pageYOffset"><code>pageYOffset</code></dfn> of type <span class="idlAttrType"><a>long</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-Window-pageYOffset">pageYOffset</a></code> attribute attribute must return the value returned by the <code><a href="#widl-Window-scrollY">scrollY</a></code> attribute.</dd>
<dt class="attribute" id="widl-Window-screenX">
<dfn id="widl-Window-screenX"><code>screenX</code></dfn> of type <span class="idlAttrType"><a>long</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-MouseEvent-screenX">screenX</a></code> 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.</dd>
<dt class="attribute" id="widl-Window-screenY">
<dfn id="widl-Window-screenY"><code>screenY</code></dfn> of type <span class="idlAttrType"><a>long</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-MouseEvent-screenY">screenY</a></code> 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.</dd>
<dt class="attribute" id="widl-Window-outerWidth">
<dfn id="widl-Window-outerWidth"><code>outerWidth</code></dfn> of type <span class="idlAttrType"><a>long</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-Window-outerWidth">outerWidth</a></code> attribute must return the width of the    client window. If there is no client window this    attribute must return zero.</dd>
<dt class="attribute" id="widl-Window-outerHeight">
<dfn id="widl-Window-outerHeight"><code>outerHeight</code></dfn> of type <span class="idlAttrType"><a>long</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-Window-outerHeight">outerHeight</a></code> attribute must return the height of the    client window. If there is no client window this    attribute must return zero.</dd>
</dl>
<dl class="methods">
<dt class="method" id="widl-Window-matchMedia-MediaQueryList-DOMString-query">
<dfn id="widl-Window-matchMedia"><code>matchMedia</code></dfn> (<span class="idlParam"><span class="idlParamType"><a>DOMString</a></span> <span class="idlParamName">query</span></span>), returns <span class="idlMethType"><a>MediaQueryList</a></span></dt>
<dd>
<p>When the <code><a href="#widl-Window-matchMedia">matchMedia</a></code> operation is invoked these steps must be run:</p>    <ol>     <li><p>Let <var title="">parsed_media_query_list</var> be the result of     <a class="external" href="http://dvcs.w3.org/hg/csswg/raw-file/tip/cssom/Overview.html#parse-a-media-query-list" title="parse a media query list">parsing</a>     <var title="">media_query_list</var>.</li>     <li><p>Return a <em>new</em> <code>MediaQueryList</code> object,     associated with the <code class="external"><a href="http://www.whatwg.org/specs/web-apps/current-work/multipage/browsers.html#window">Window</a></code> object, with     <var title="">parsed_media_query_list</var> as its associated     media query list.</li>    </ol></dd>
<dt class="method" id="widl-Window-scroll-void-long-x-long-y">
<dfn id="widl-Window-scroll"><code>scroll</code></dfn> (<span class="idlParam"><span class="idlParamType"><a>long</a></span> <a class="idlParamName" href="#widl-MouseEvent-x">x</a></span>, <span class="idlParam"><span class="idlParamType"><a>long</a></span> <a class="idlParamName" href="#widl-MouseEvent-y">y</a></span>), returns <span class="idlMethType"><a>void</a></span></dt>
<dd>
<p>When the <code><a href="#widl-Window-scroll">scroll</a></code> operation is invoked these steps must be run:</p>    <ol>     <li>      <dl>       <dt>If <a href="#document-content">document content</a> can have overflow to the right       <dd><p>Let <var title="">x</var> be max(0, min(<var title="">x</var>,       <a href="#content">content</a> width - <a href="#content-edge">content edge</a>       width)).</dd>       <dt>If <a href="#document-content">document content</a> can have overflow to the left       (under right-to-left conditions)       <dd><p>Let <var title="">x</var> be min(0, max(<var title="">x</var>,       <a href="#content-edge">content edge</a> width - <a href="#content">content</a>       width)).</dd>      </dl>     </li>     <li><p>Let <var title="">y</var> be max(0, min(<var title="">y</var>,     <a href="#document-content">document content</a> height - <a href="#viewport">viewport</a>     height excluding the size of a rendered scroll bar (if any))).</li>     <li><p>Align the x-coordinate <var title="">x</var> of the     <a href="#document-content">document content</a> with the left of the <a href="#viewport">viewport</a>     and align the y-coordinate <var title="">y</var> of the <a href="#document-content">document     content</a> with the top of the <a href="#viewport">viewport</a>.</li>     <li><p>If the aligning caused content to move <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#queue-a-task">queue a task</a> to     <a class="external" href="http://dom.spec.whatwg.org/#concept-event-fire" title="concept-event-fire">fire an event</a>     named <code title="event-scroll">scroll</code> that bubbles at the     <code class="external"><a href="http://dom.spec.whatwg.org/#document">Document</a></code> object, unless a     <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#concept-task" title="concept-task">task</a> to fire that event at the <code class="external"><a href="http://dom.spec.whatwg.org/#document">Document</a></code> object     was already <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#queue-a-task" title="queue a task">queued</a>.</li>    </ol></dd>
<dt class="method" id="widl-Window-scrollTo-void-long-x-long-y">
<dfn id="widl-Window-scrollTo"><code>scrollTo</code></dfn> (<span class="idlParam"><span class="idlParamType"><a>long</a></span> <a class="idlParamName" href="#widl-MouseEvent-x">x</a></span>, <span class="idlParam"><span class="idlParamType"><a>long</a></span> <a class="idlParamName" href="#widl-MouseEvent-y">y</a></span>), returns <span class="idlMethType"><a>void</a></span></dt>
<dd>
<p>When the <code><a href="#widl-Window-scrollTo">scrollTo</a></code> operation is invoked, the user agent must act as if the    <code title="widl-Window-scroll">scroll()</code> method was invoked with the same arguments.</dd>
<dt class="method" id="widl-Window-scrollBy-void-long-x-long-y">
<dfn id="widl-Window-scrollBy"><code>scrollBy</code></dfn> (<span class="idlParam"><span class="idlParamType"><a>long</a></span> <a class="idlParamName" href="#widl-MouseEvent-x">x</a></span>, <span class="idlParam"><span class="idlParamType"><a>long</a></span> <a class="idlParamName" href="#widl-MouseEvent-y">y</a></span>), returns <span class="idlMethType"><a>void</a></span></dt>
<dd>
<p>When the <code><a href="#widl-Window-scrollBy">scrollBy</a></code> operation is invoked, the user agent must act as if the    <code title="widl-Window-scroll">scroll()</code> method was invoked with    <var title="">x</var> plus <code title="widl-Window-scrollX">scrollX</code>    as first argument and <var title="">y</var> plus    <code title="widl-Window-scrollY">scrollY</code> as second argument.</dd>
</dl>


  <h3 id="the-mediaquerylist-interface"><span class="secno">4.1 </span>The <code title="">MediaQueryList</code> Interface</h3>

  <p>A <code>MediaQueryList</code> interface has an associated media query list set on creation and an associated  <dfn id="list-of-media-query-list-listeners">list of media query list listeners</dfn>, which is initially empty.</p>  <p>If the associated media query list changes in evaluation then, for each  listener in the <a href="#list-of-media-query-list-listeners">list of media query list listeners</a> — in  appending order, <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#queue-a-task">queue a task</a> that invokes the listener,  passing as argument the <code>MediaQueryList</code> object.</p>  <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><code>function handleOrientationChange(mql) {    if(mql.matches) // landscape      …    else      …  }  var mql = matchMedia("(orientation:landscape)")  mql.addListener(handleOrientationChange)</code></pre>  </div>
<pre class="idl"><span class="idlInterface" id="widl-def-MediaQueryList">interface <span class="idlInterfaceID">MediaQueryList</span> {
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>DOMString</a></span> <span class="idlAttrName"><a href="#widl-MediaQueryList-media">media</a></span>;</span>
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>boolean</a></span> <span class="idlAttrName"><a href="#widl-MediaQueryList-matches">matches</a></span>;</span>
<span class="idlMethod">    <span class="idlMethType"><a>void</a></span> <span class="idlMethName"><a href="#widl-MediaQueryList-addListener-void-MediaQueryListListener-listener">addListener</a></span> (<span class="idlParam"><span class="idlParamType"><a>MediaQueryListListener</a></span> <span class="idlParamName">listener</span></span>);</span>
<span class="idlMethod">    <span class="idlMethType"><a>void</a></span> <span class="idlMethName"><a href="#widl-MediaQueryList-removeListener-void-MediaQueryListListener-listener">removeListener</a></span> (<span class="idlParam"><span class="idlParamType"><a>MediaQueryListListener</a></span> <span class="idlParamName">listener</span></span>);</span>
};</span></pre>
<dl class="attributes">
<dt class="attribute" id="widl-MediaQueryList-media">
<dfn id="widl-MediaQueryList-media"><code>media</code></dfn> of type <span class="idlAttrType"><a>DOMString</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-MediaQueryList-media">media</a></code> attribute must return the    <a class="external" href="http://dvcs.w3.org/hg/csswg/raw-file/tip/cssom/Overview.html#serialize-a-media-query-list" title="serialize a media query list">serialized</a> form of the associated media query list.</dd>
<dt class="attribute" id="widl-MediaQueryList-matches">
<dfn id="widl-MediaQueryList-matches"><code>matches</code></dfn> of type <span class="idlAttrType"><a>boolean</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-MediaQueryList-matches">matches</a></code> attribute must return true if the associated media query list    matches the state of the rendered <code class="external"><a href="http://dom.spec.whatwg.org/#document">Document</a></code> and false if it does not.</dd>
</dl>
<dl class="methods">
<dt class="method" id="widl-MediaQueryList-addListener-void-MediaQueryListListener-listener">
<dfn id="widl-MediaQueryList-addListener"><code>addListener</code></dfn> (<span class="idlParam"><span class="idlParamType"><a>MediaQueryListListener</a></span> <span class="idlParamName">listener</span></span>), returns <span class="idlMethType"><a>void</a></span></dt>
<dd>
<p>When the <code><a href="#widl-MediaQueryList-addListener">addListener</a></code> operation is invoked <var title="">listener</var> must be    appended to the <a href="#list-of-media-query-list-listeners">list of media query list listeners</a>, unless    it is already in the <a href="#list-of-media-query-list-listeners">list of media query list listeners</a>.</dd>
<dt class="method" id="widl-MediaQueryList-removeListener-void-MediaQueryListListener-listener">
<dfn id="widl-MediaQueryList-removeListener"><code>removeListener</code></dfn> (<span class="idlParam"><span class="idlParamType"><a>MediaQueryListListener</a></span> <span class="idlParamName">listener</span></span>), returns <span class="idlMethType"><a>void</a></span></dt>
<dd>
<p>When the <code><a href="#widl-MediaQueryList-removeListener">removeListener</a></code> operation is invoked <var title="">listener</var> must be    removed from the <a href="#list-of-media-query-list-listeners">list of media query list listeners</a>.</dd>
</dl>


<pre class="idl"><span class="idlInterface" id="widl-def-MediaQueryListListener">[NoInterfaceObject]
interface <span class="idlInterfaceID">MediaQueryListListener</span> {
<span class="idlMethod">    <span class="idlMethType"><a>void</a></span> <span class="idlMethName"><a href="#widl-MediaQueryListListener-handleChange-void-MediaQueryList-list">handleChange</a></span> (<span class="idlParam"><span class="idlParamType"><a>MediaQueryList</a></span> <span class="idlParamName">list</span></span>);</span>
};</span></pre>
<dl class="methods">
<dt class="method" id="widl-MediaQueryListListener-handleChange-void-MediaQueryList-list">
<dfn id="widl-MediaQueryListListener-handleChange"><code>handleChange</code></dfn> (<span class="idlParam"><span class="idlParamType"><a>MediaQueryList</a></span> <span class="idlParamName">list</span></span>), returns <span class="idlMethType"><a>void</a></span></dt>
</dl>


  <h3 id="the-screen-interface"><span class="secno">4.2 </span>The <code title="">Screen</code> Interface</h3>

  <p>As its name suggests, the <code><a href="#widl-Window-screen">Screen</a></code> interface represents information about the screen of the output device.</p>
<pre class="idl"><span class="idlInterface" id="widl-def-Screen">interface <a class="idlInterfaceID" href="#widl-Window-screen">Screen</a> {
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>unsigned long</a></span> <span class="idlAttrName"><a href="#widl-Screen-availWidth">availWidth</a></span>;</span>
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>unsigned long</a></span> <span class="idlAttrName"><a href="#widl-Screen-availHeight">availHeight</a></span>;</span>
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>unsigned long</a></span> <span class="idlAttrName"><a href="#widl-Screen-width">width</a></span>;</span>
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>unsigned long</a></span> <span class="idlAttrName"><a href="#widl-Screen-height">height</a></span>;</span>
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>unsigned long</a></span> <span class="idlAttrName"><a href="#widl-Screen-colorDepth">colorDepth</a></span>;</span>
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>unsigned long</a></span> <span class="idlAttrName"><a href="#widl-Screen-pixelDepth">pixelDepth</a></span>;</span>
};</span></pre>
<dl class="attributes">
<dt class="attribute" id="widl-Screen-availWidth">
<dfn id="widl-Screen-availWidth"><code>availWidth</code></dfn> of type <span class="idlAttrType"><a>unsigned long</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-Screen-availWidth">availWidth</a></code> attribute must return the available width of the rendering surface of the output device.</dd>
<dt class="attribute" id="widl-Screen-availHeight">
<dfn id="widl-Screen-availHeight"><code>availHeight</code></dfn> of type <span class="idlAttrType"><a>unsigned long</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-Screen-availHeight">availHeight</a></code> attribute must return the available height of the rendering surface of the output device.</dd>
<dt class="attribute" id="widl-Screen-width">
<dfn id="widl-Screen-width"><code>width</code></dfn> of type <span class="idlAttrType"><a>unsigned long</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-ClientRect-width">width</a></code> attribute must return the width of the output device.</dd>
<dt class="attribute" id="widl-Screen-height">
<dfn id="widl-Screen-height"><code>height</code></dfn> of type <span class="idlAttrType"><a>unsigned long</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-ClientRect-height">height</a></code> attribute must return the height of the output device.</dd>
<dt class="attribute" id="widl-Screen-colorDepth">
<dfn id="widl-Screen-colorDepth"><code>colorDepth</code></dfn> of type <span class="idlAttrType"><a>unsigned long</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-Screen-colorDepth">colorDepth</a></code> attribute must return the number of bits allocated to    colors (i.e. excluding the alpha channel) in the output device. If the    output device does not support colors these attributes    must return zero.</dd>
<dt class="attribute" id="widl-Screen-pixelDepth">
<dfn id="widl-Screen-pixelDepth"><code>pixelDepth</code></dfn> of type <span class="idlAttrType"><a>unsigned long</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-Screen-pixelDepth">pixelDepth</a></code> attribute must return the value returned by the <code><a href="#widl-Screen-colorDepth">colorDepth</a></code> attributed.</dd>
</dl>


  <h2 id="extensions-to-the-document-interface"><span class="secno">5 </span>Extensions to the <code title="">Document</code> Interface</h2>


<pre class="idl"><span class="idlInterface" id="widl-def-Document">partial interface <span class="idlInterfaceID">Document</span> {
<span class="idlMethod">    <span class="idlMethType"><a>Element</a>?</span> <span class="idlMethName"><a href="#widl-Document-elementFromPoint-Element-float-x-float-y">elementFromPoint</a></span> (<span class="idlParam"><span class="idlParamType"><a>float</a></span> <a class="idlParamName" href="#widl-MouseEvent-x">x</a></span>, <span class="idlParam"><span class="idlParamType"><a>float</a></span> <a class="idlParamName" href="#widl-MouseEvent-y">y</a></span>);</span>
<span class="idlMethod">    <span class="idlMethType"><a>CaretPosition</a>?</span> <span class="idlMethName"><a href="#widl-Document-caretPositionFromPoint-CaretPosition-float-x-float-y">caretPositionFromPoint</a></span> (<span class="idlParam"><span class="idlParamType"><a>float</a></span> <a class="idlParamName" href="#widl-MouseEvent-x">x</a></span>, <span class="idlParam"><span class="idlParamType"><a>float</a></span> <a class="idlParamName" href="#widl-MouseEvent-y">y</a></span>);</span>
};</span></pre>
<dl class="methods">
<dt class="method" id="widl-Document-elementFromPoint-Element-float-x-float-y">
<dfn id="widl-Document-elementFromPoint"><code>elementFromPoint</code></dfn> (<span class="idlParam"><span class="idlParamType"><a>float</a></span> <a class="idlParamName" href="#widl-MouseEvent-x">x</a></span>, <span class="idlParam"><span class="idlParamType"><a>float</a></span> <a class="idlParamName" href="#widl-MouseEvent-y">y</a></span>), returns <span class="idlMethType"><a>Element</a>?</span></dt>
<dd>
<p>The <code><a href="#widl-Document-elementFromPoint">elementFromPoint</a></code> operation must return the element at coordinates <var><a href="#widl-MouseEvent-x">x</a></var>,<var><a href="#widl-MouseEvent-y">y</a></var> in the <a href="#viewport">viewport</a>. The element to be returned is determined    through hit testing. If either argument is negative, <var title="">x</var> is greater than the <a href="#viewport">viewport</a> width excluding the size of a rendered scroll    bar (if any), or <var title="">y</var> is greater than the <a href="#viewport">viewport</a> height excluding the size of a rendered scroll bar (if any), the method must    return null. If there is no element at the given position the method must return the root element, if any, or null otherwise.</dd>
<dt class="method" id="widl-Document-caretPositionFromPoint-CaretPosition-float-x-float-y">
<dfn id="widl-Document-caretPositionFromPoint"><code>caretPositionFromPoint</code></dfn> (<span class="idlParam"><span class="idlParamType"><a>float</a></span> <a class="idlParamName" href="#widl-MouseEvent-x">x</a></span>, <span class="idlParam"><span class="idlParamType"><a>float</a></span> <a class="idlParamName" href="#widl-MouseEvent-y">y</a></span>), returns <span class="idlMethType"><a>CaretPosition</a>?</span></dt>
<dd>
<p>The <code><a href="#widl-Document-caretPositionFromPoint">caretPositionFromPoint</a></code> operation must return the result of running these steps:</p>    <ol>     <li><p>If either argument is negative, <var title="">x</var> is greater     than the <a href="#viewport">viewport</a> width excluding the size of a rendered     scroll bar (if any), <var title="">y</var> is greather than the     <a href="#viewport">viewport</a> height excluding the size of a rendered scroll bar     (if any) return null.</li>     <li><p>If at the coordinates <var title="">x</var>,<var title="">y</var>     in the <a href="#viewport">viewport</a> no text insertion point indicator would have     been inserted return null.</li>     <li>      <p>If at the coordinates <var title="">x</var>,<var title="">y</var>      in the <a href="#viewport">viewport</a> a text insertion point indicator would have      been inserted in a text entry widget which is also a replaced element      return a <a href="#caret-position">caret position</a> with its properties set as      follows:</p>      <dl>       <dt><a href="#caret-node">caret node</a></dt>       <dd><p>The node corresponding to the text entry widget.</dd>       <dt><a href="#caret-offset">caret offset</a></dt>       <dd><p>The amount of 16-bit units to the left of where the       text insertion point indicator would have inserted.</dd>       <dt><a href="#caret-range">caret range</a></dt>       <dd><p>null</dd>      </dl>     </li>     <li>      <p>Otherwise, return a <a href="#caret-position">caret position</a> where the      <a href="#caret-range">caret range</a> is a collapsed      <code class="external"><a href="http://dom.spec.whatwg.org/#range">Range</a></code> object for the position      where the text insertion point indicator would have been inserted and      the other properties are set as follows:</p>      <dl>       <dt><a href="#caret-node">caret node</a></dt>       <dd><p>The <code class="external" title="dom-Range-startContainer"><a href="http://dom.spec.whatwg.org/#dom-range-startcontainer">startContainer</a></code>       of the <a href="#caret-range">caret range</a>.</dd>       <dt><a href="#caret-offset">caret offset</a></dt>       <dd><p>The <code class="external" title="dom-Range-startOffset"><a href="http://dom.spec.whatwg.org/#dom-range-startoffset">startOffset</a></code> of       the <a href="#caret-range">caret range</a>.</p>      </dl>     </li>    </ol>    <p class="note">The specifics of hit testing are out of scope of this    specification and therefore the exact details of    <code title="widl-Document-elementFromPoint">elementFromPoint()</code> and    <code title="widl-Document-caretPositionFromPoint">caretPositionFromPoint()</code>    are therefore too. Hit testing will hopefully be defined in a future    revision of CSS or HTML.</dd>
</dl>


  <h3 id="the-caretposition-interface"><span class="secno">5.1 </span>The <code title="">CaretPosition</code> Interface</h3>

  <p>A <dfn id="caret-position">caret position</dfn> gives the position of a text insertion point indicator. It always has an associated  <dfn id="caret-node">caret node</dfn>, <dfn id="caret-offset">caret offset</dfn>, and <dfn id="caret-range">caret range</dfn>. It is represented by a <code>CaretPosition</code> interface.</p>
<pre class="idl"><span class="idlInterface" id="widl-def-CaretPosition">interface <span class="idlInterfaceID">CaretPosition</span> {
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>Node</a></span> <span class="idlAttrName"><a href="#widl-CaretPosition-offsetNode">offsetNode</a></span>;</span>
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>unsigned long</a></span> <span class="idlAttrName"><a href="#widl-CaretPosition-offset">offset</a></span>;</span>
<span class="idlMethod">    <span class="idlMethType"><a>ClientRect</a>?</span> <span class="idlMethName"><a href="#widl-CaretPosition-getClientRect-ClientRect">getClientRect</a></span> ();</span>
};</span></pre>
<dl class="attributes">
<dt class="attribute" id="widl-CaretPosition-offsetNode">
<dfn id="widl-CaretPosition-offsetNode"><code>offsetNode</code></dfn> of type <span class="idlAttrType"><a>Node</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-
A3CA
CaretPosition-offsetNode">offsetNode</a></code> attribute  must return the <a href="#caret-node">caret node</a>.</dd>
<dt class="attribute" id="widl-CaretPosition-offset">
<dfn id="widl-CaretPosition-offset"><code>offset</code></dfn> of type <span class="idlAttrType"><a>unsigned long</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-CaretPosition-offset">offset</a></code> attribute  must return the <a href="#caret-offset">caret offset</a>.</dd>
</dl>
<dl class="methods">
<dt class="method" id="widl-CaretPosition-getClientRect-ClientRect">
<dfn id="widl-CaretPosition-getClientRect"><code>getClientRect</code></dfn> (), returns <span class="idlMethType"><a>ClientRect</a>?</span></dt>
<dd>
<p>The <code><a href="#widl-CaretPosition-getClientRect">getClientRect</a></code> operation must follow these steps, aborting on the first step that    returns a value:</p>    <ol>     <li>      <p>If <a href="#caret-range">caret range</a> is not null:      <ol>       <li><p>Let <var>list</var> be the result of invoking the       <code title="widl-Range-getClientRects">getClientRects()</code> method on the       range.       <li><p>If <var>list</var> is empty, return null.       <li><p>Return the <code>ClientRect</code> object in <var>list</var> at index 0.      </ol>     <li><p>If <a href="#caret-node">caret node</a> is a text entry widget that is a replaced element,     and that is in the document, return a <code>ClientRect</code> object for the caret     in the widget as represented by the <a href="#caret-offset">caret offset</a> value.     <li><p>Return null.    </ol></dd>
</dl>


  <h2 id="extensions-to-the-element-interface"><span class="secno">6 </span>Extensions to the <code title="">Element</code> Interface</h2>


<pre class="idl"><span class="idlInterface" id="widl-def-Element">partial interface <span class="idlInterfaceID">Element</span> {
<span class="idlMethod">    <span class="idlMethType"><a>ClientRectList</a></span> <span class="idlMethName"><a href="#widl-Element-getClientRects-ClientRectList">getClientRects</a></span> ();</span>
<span class="idlMethod">    <span class="idlMethType"><a>ClientRect</a></span> <span class="idlMethName"><a href="#widl-Element-getBoundingClientRect-ClientRect">getBoundingClientRect</a></span> ();</span>
<span class="idlMethod">    <span class="idlMethType"><a>void</a></span> <span class="idlMethName"><a href="#widl-Element-scrollIntoView-void-boolean-top">scrollIntoView</a></span> (<span class="idlParam">optional <span class="idlParamType"><a>boolean</a></span> <a class="idlParamName" href="#widl-ClientRect-top">top</a></span>);</span>
<span class="idlAttribute">    attribute <span class="idlAttrType"><a>long</a></span> <span class="idlAttrName"><a href="#widl-Element-scrollTop">scrollTop</a></span>;</span>
<span class="idlAttribute">    attribute <span class="idlAttrType"><a>long</a></span> <span class="idlAttrName"><a href="#widl-Element-scrollLeft">scrollLeft</a></span>;</span>
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>long</a></span> <span class="idlAttrName"><a href="#widl-Element-scrollWidth">scrollWidth</a></span>;</span>
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>long</a></span> <span class="idlAttrName"><a href="#widl-Element-scrollHeight">scrollHeight</a></span>;</span>
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>long</a></span> <span class="idlAttrName"><a href="#widl-Element-clientTop">clientTop</a></span>;</span>
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>long</a></span> <span class="idlAttrName"><a href="#widl-Element-clientLeft">clientLeft</a></span>;</span>
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>long</a></span> <span class="idlAttrName"><a href="#widl-Element-clientWidth">clientWidth</a></span>;</span>
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>long</a></span> <span class="idlAttrName"><a href="#widl-Element-clientHeight">clientHeight</a></span>;</span>
};</span></pre>
<dl class="attributes">
<dt class="attribute" id="widl-Element-scrollTop">
<dfn id="widl-Element-scrollTop"><code>scrollTop</code></dfn> of type <span class="idlAttrType"><a>long</a></span></dt>
<dd>
<p>The <code><a href="#widl-Element-scrollTop">scrollTop</a></code> attribute must return the result of running these steps:</p>    <ol>     <li><p>If the element does not have any associated <a href="#css-layout-box">CSS layout box</a> or the     element is the root element and the <code class="external"><a href="http://dom.spec.whatwg.org/#document">Document</a></code> is in     <a class="external" href="http://dom.spec.whatwg.org/#concept-document-quirks" title="concept-document-quirks">quirks mode</a> return zero and terminate these steps.</li>     <li><p>If the element is the root element return the value of     <code title="widl-Window-scrollY">scrollY</code>.</li>     <li><p>If the element is <a href="#the-html-body-element">the HTML <code>body</code> element</a>,     the <code class="external"><a href="http://dom.spec.whatwg.org/#document">Document</a></code> is in <a class="external" href="http://dom.spec.whatwg.org/#concept-document-quirks" title="concept-document-quirks">quirks mode</a>, and the element     does not have any overflow, return the value of     <code title="widl-Window-scrollY">scrollY</code>.</li>     <li><p>Return the y-coordinate of the <a href="#content">content</a> at the     alignment point with the top of the <a href="#content-edge">content edge</a> of the     element.</li>    </ol>    <p>When setting the <code><a href="#widl-Element-scrollTop">scrollTop</a></code> attribute these steps must be run:</p>    <ol>     <li><p>Let <var title="">y</var> be the given value.</li>     <li><p>If the element does not have any associated <a href="#css-layout-box">CSS layout box</a>, the     element is the root element and the <code class="external"><a href="http://dom.spec.whatwg.org/#document">Document</a></code> is in     <a class="external" href="http://dom.spec.whatwg.org/#concept-document-quirks" title="concept-document-quirks">quirks mode</a>, or the element has no overflow, terminate these     steps.</li>     <li><p>If the element is the root element invoke     <code title="widl-Window-scroll">scroll()</code> with zero as first     argument and <var title="">y</var> as second.</li>     <li><p>If the element is <a href="#the-html-body-element">the HTML <code>body</code> element</a>,     the <code class="external"><a href="http://dom.spec.whatwg.org/#document">Document</a></code> is in <a class="external" href="http://dom.spec.whatwg.org/#concept-document-quirks" title="concept-document-quirks">quirks mode</a>, and the element     does not have any vertical overflow, invoke     <code title="widl-Window-scroll">scroll()</code> with     <code title="widl-Window-scrollX">scrollX</code> as first     argument and <var title="">y</var> as second.</li>     <li><p><a href="#scroll-an-element" title="scroll an element">Scroll the element</a> to     <code title="widl-Element-scrollLeft">scrollLeft</code>,<var title="">y</var>.    </ol></dd>
<dt class="attribute" id="widl-Element-scrollLeft">
<dfn id="widl-Element-scrollLeft"><code>scrollLeft</code></dfn> of type <span class="idlAttrType"><a>long</a></span></dt>
<dd>
<p>The <code><a href="#widl-Element-scrollLeft">scrollLeft</a></code> attribute must return the result of running these steps:</p>    <ol>     <li><p>If the element does not have any associated <a href="#css-layout-box">CSS layout box</a> or the     element is the root element and the <code class="external"><a href="http://dom.spec.whatwg.org/#document">Document</a></code> is in     <a class="external" href="http://dom.spec.whatwg.org/#concept-document-quirks" title="concept-document-quirks">quirks mode</a> return zero and terminate these steps.</li>     <li><p>If the element is the root element return the value of     <code title="widl-Window-scrollX">scrollX</code>.</li>     <li><p>If the element is <a href="#the-html-body-element">the HTML <code>body</code> element</a>,     the <code class="external"><a href="http://dom.spec.whatwg.org/#document">Document</a></code> is in <a class="external" href="http://dom.spec.whatwg.org/#concept-document-quirks" title="concept-document-quirks">quirks mode</a>, and the element     does not have any overflow, return the value of     <code title="widl-Window-scrollX">scrollX</code>.</li>     <li><p>Return the x-coordinate of the <a href="#content">content</a> at the     alignment point with the left of the <a href="#content-edge">content edge</a> of the     element.</li>    </ol>    <p>When setting the <code><a href="#widl-Element-scrollLeft">scrollLeft</a></code> attribute these steps must be run:</p>    <ol>     <li><p>Let <var title="">x</var> be the given value.</li>     <li><p>If the element does not have any associated <a href="#css-layout-box">CSS layout box</a>, the     element is the root element and the <code class="external"><a href="http://dom.spec.whatwg.org/#document">Document</a></code> is in     <a class="external" href="http://dom.spec.whatwg.org/#concept-document-quirks" title="concept-document-quirks">quirks mode</a>, or the element has no overflow, terminate these     steps.</li>     <li><p>If the element is the root element invoke     <code title="widl-Window-scroll">scroll()</code> with     <var title="">x</var> as first argument and zero as second.</li>     <li><p>If the element is <a href="#the-html-body-element">the HTML <code>body</code> element</a>,     the <code class="external"><a href="http://dom.spec.whatwg.org/#document">Document</a></code> is in <a class="external" href="http://dom.spec.whatwg.org/#concept-document-quirks" title="concept-document-quirks">quirks mode</a>, and the element     does not have any vertical overflow, invoke     <code title="widl-Window-scroll">scroll()</code> with     <var title="">x</var> as first argument and     <code title="widl-Window-scrollY">scrollY</code> as second.</li>     <li><p><a href="#scroll-an-element" title="Scroll an element">Scroll the element</a> to     <var title="">x</var>,<code title="widl-Element-scrollTop">scrollTop</code>.    </ol></dd>
<dt class="attribute" id="widl-Element-scrollWidth">
<dfn id="widl-Element-scrollWidth"><code>scrollWidth</code></dfn> of type <span class="idlAttrType"><a>long</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-Element-scrollWidth">scrollWidth</a></code> attribute must return the result of running these steps:</p>    <ol>     <li><p>If the element does not have any associated <a href="#css-layout-box">CSS layout box</a> return     zero and terminate these steps.</li>     <li><p>If the element is the root element and the     <code class="external"><a href="http://dom.spec.whatwg.org/#document">Document</a></code> is not in     <a class="external" href="http://dom.spec.whatwg.org/#concept-document-quirks" title="concept-document-quirks">quirks mode</a>     return max(<a href="#document-content">document content</a> width, value of <code title="widl-Window-innerWidth">innerWidth</code>).</li>     <li><p>If the element is <a href="#the-html-body-element">the HTML <code>body</code> element</a>     and the <code class="external"><a href="http://dom.spec.whatwg.org/#document">Document</a></code> is in     <a class="external" href="http://dom.spec.whatwg.org/#concept-document-quirks" title="concept-document-quirks">quirks mode</a>     return max(<a href="#document-content">document content</a> width, value of <code title="widl-Window-innerWidth">innerWidth</code>).</li>     <li><p>Return the computed value of the '<code>padding-left</code>'     property, plus the computed value of the '<code>padding-right</code>',     plus the <a href="#content">content</a> width of the element.</li>    </ol></dd>
<dt class="attribute" id="widl-Element-scrollHeight">
<dfn id="widl-Element-scrollHeight"><code>scrollHeight</code></dfn> of type <span class="idlAttrType"><a>long</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-Element-scrollHeight">scrollHeight</a></code> attribute must return the result of running these steps:</p>    <ol>     <li><p>If the element does not have any associated <a href="#css-layout-box">CSS layout box</a> return     zero and terminate these steps.</li>     <li><p>If the element is the root element and the     <code class="external"><a href="http://dom.spec.whatwg.org/#document">Document</a></code> is not in     <a class="external" href="http://dom.spec.whatwg.org/#concept-document-quirks" title="concept-document-quirks">quirks mode</a>     return max(<a href="#document-content">document content</a> height, value of <code title="widl-Window-innerHeight">innerHeight</code>).</li>     <li><p>If the element is <a href="#the-html-body-element">the HTML <code>body</code> element</a>     and the <code class="external"><a href="http://dom.spec.whatwg.org/#document">Document</a></code> is in     <a class="external" href="http://dom.spec.whatwg.org/#concept-document-quirks" title="concept-document-quirks">quirks mode</a>     return max(<a href="#document-content">document content</a> height, value of <code title="widl-Window-innerHeight">innerHeight</code>).</li>     <li><p>Return the computed value of the '<code>padding-top</code>'     property, plus the computed value of the '<code>padding-bottom</code>',     plus the <a href="#content">content</a> height of the element.</li>    </ol></dd>
<dt class="attribute" id="widl-Element-clientTop">
<dfn id="widl-Element-clientTop"><code>clientTop</code></dfn> of type <span class="idlAttrType"><a>long</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-Element-clientTop">clientTop</a></code> attribute returns the computed value of the    '<code>border-top-width</code>' property plus the width of any scrollbar    rendered between the top <a href="#padding-edge">padding edge</a> and the top    <a href="#border-edge">border edge</a>.</dd>
<dt class="attribute" id="widl-Element-clientLeft">
<dfn id="widl-Element-clientLeft"><code>clientLeft</code></dfn> of type <span class="idlAttrType"><a>long</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-Element-clientLeft">clientLeft</a></code> attribute returns the computed value of the    '<code>border-left-width</code>' property plus the width of any scrollbar    rendered between the left <a href="#padding-edge">padding edge</a> and the left    <a href="#border-edge">border edge</a>.</dd>
<dt class="attribute" id="widl-Element-clientWidth">
<dfn id="widl-Element-clientWidth"><code>clientWidth</code></dfn> of type <span class="idlAttrType"><a>long</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-Element-clientWidth">clientWidth</a></code> attribute returns the    <a href="#viewport">viewport</a> width excluding the size of a rendered scroll bar    (if any) if the element is the root element and the    width of the <a href="#padding-edge">padding edge</a> (excluding the width of any    rendered scrollbar between the <a href="#padding-edge">padding edge</a> and the    <a href="#border-edge">border edge</a>) otherwise.</dd>
<dt class="attribute" id="widl-Element-clientHeight">
<dfn id="widl-Element-clientHeight"><code>clientHeight</code></dfn> of type <span class="idlAttrType"><a>long</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-Element-clientHeight">clientHeight</a></code> attribute returns the    <a href="#viewport">viewport</a> height excluding the size of a rendered scroll bar    (if any) if the element is the root element and the    height of the <a href="#padding-edge">padding edge</a> (excluding the height of any    rendered scrollbar between the <a href="#padding-edge">padding edge</a> and the    <a href="#border-edge">border edge</a>) otherwise.</dd>
</dl>
<dl class="methods">
<dt class="method" id="widl-Element-getClientRects-ClientRectList">
<dfn id="widl-Element-getClientRects"><code>getClientRects</code></dfn> (), returns <span class="idlMethType"><a>ClientRectList</a></span></dt>
<dd>
<p>The <code><a href="#widl-Range-getClientRects">getClientRects</a></code> operation, when invoked, must return the result of the following algorithm:</p>    <ol>     <li><p>If the element on which it was invoked does not have an associated     <a href="#css-layout-box">CSS layout box</a> and is not in the <code>http://www.w3.org/2000/svg</code>     namespace return an empty <code>ClientRectList</code> object and stop     this algorithm.</li>     <li><p>If the element does not have an associated <a href="#css-layout-box">CSS layout box</a> and is     in the <code>http://www.w3.org/2000/svg</code> namespace return a     <code>ClientRectList</code> object containing a single     <code>ClientRect</code> object that describes the bounding box of the     element as defined by the SVG specification.     <a href="#refsSVG">[SVG]</a></li>     <li>      <p>Return a <code>ClientRectList</code> object containing a list of      <code>ClientRect</code> objects in content order describing the border      boxes (including those with a height or width of zero) with the      following constraints:</p>      <ul>       <li><p>If the element on which the method was invoked has a computed       value for <code>display</code> property of <code>table</code> or       <code>inline-table</code> include both the table box and the caption       box, if any, but not the anonymous container box.</li>       <li><p>Replace each       <a href="http://www.w3.org/TR/CSS21/visuren.html#anonymous-block-level">anonymous       block box</a> with its child box(es) and repeat this until no anonymous       block boxes are left in the final list.</li>      </ul>     </li>    </ol></dd>
<dt class="method" id="widl-Element-getBoundingClientRect-ClientRect">
<dfn id="widl-Element-getBoundingClientRect"><code>getBoundingClientRect</code></dfn> (), returns <span class="idlMethType"><a>ClientRect</a></span></dt>
<dd>
<p>The <code><a href="#widl-Range-getBoundingClientRect">getBoundingClientRect</a></code> operation, when invoked, must return the result of the  following algorithm:</p>    <ol>     <li><p>Let <var>list</var> be the result of invoking     <code title="widl-Element-getClientRects">getClientRects()</code> on the     same element this method was invoked on.</li>     <li><p>If the <var>list</var> is empty return a <code>ClientRect</code>     object whose <code title="widl-ClientRect-top">top</code>,     <code title="widl-ClientRect-right">right</code>,     <code title="widl-ClientRect-bottom">bottom</code> and     <code title=&q
67F6
uot;widl-ClientRect-left">left</code> members are zero.</li>     <li><p>Otherwise, return a <code>ClientRect</code> object describing the     smallest rectangle that includes the first rectangle in <var>list</var>     and all of the remaining rectangles of which the height or width is not     zero.</li>    </ol>    <div class="example">     <p>The following snippet gets the dimensions of the first     <code>div</code> element in a document:</p>     <pre><code>var example = document.getElementsByTagName("div")[0].getBoundingClientRect();
var exampleWidth = example.width;
var exampleHeight = example.height;</code></pre>    </div></dd>
<dt class="method" id="widl-Element-scrollIntoView-void-boolean-top">
<dfn id="widl-Element-scrollIntoView"><code>scrollIntoView</code></dfn> (<span class="idlParam">optional <span class="idlParamType"><a>boolean</a></span> <a class="idlParamName" href="#widl-ClientRect-top">top</a></span>), returns <span class="idlMethType"><a>void</a></span></dt>
<dd>
<p>The must run these steps:</p>    <ol>     <li><p>If the element does not have any associated <a href="#css-layout-box">CSS layout box</a> terminate these steps.</li>     <li><p><a href="#scroll-an-element-into-view" title="scroll an element into view">Scroll the element into view</a> with the         <i title="">align to top flag</i> set if <var title="">top</var> is true or omitted.</li>    </ol></dd>
</dl>


  <h3 id="the-getclientrects-and-getboundingclientrect-methods"><span class="secno">6.1 </span>The <code title="">getClientRects()</code> and
  <code title="">getBoundingClientRect()</code> methods</h3>

  <p>The <code title="widl-Element-getClientRects">getClientRects()</code> and <code title="widl-Element-getBoundingClientRect">getBoundingClientRect()</code>
  methods provide information about the position of the border box edges of
  an element relative to the viewport. The objects these methods return
  must be static. That is, changes to the underlying
  document are not reflected in the objects.</p>

  <h3 id="element-scrolling-members"><span class="secno">6.2 </span><code title="">Element</code> Scrolling Members</h3>

  <p>To <dfn id="scroll-an-element-into-view">scroll an element into view</dfn>, optionally with an
  <i title="">align to top flag</i> set, means to run these steps for each
  ancestor element or <a href="#viewport">viewport</a> that establishes a
  scrolling box, in order of innermost to outermost scrolling box:</p>

  <ol>
   <li><p>If the <code class="external"><a href="http://dom.spec.whatwg.org/#document">Document</a></code> associated
   with the element to be
   scrolled into view is not <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/origin-0.html#same-origin">same origin</a> with the
   <code class="external"><a href="http://dom.spec.whatwg.org/#document">Document</a></code> associated with the element or
   <a href="#viewport">viewport</a> associated with the scrolling box, terminate these
   steps.</li>

   <li><p>If the <i title="">align to top flag</i> is set align the top of
   the border box of the element to be scrolled into view with the top of
   the scrolling box.</li>

   <li><p>Otherwise, if the <i title="">align to top flag</i> is not set
   align the bottom of the border box of the element to be scrolled into
   view with the bottom of the scrolling box.</li>

   <li><p>Align the left of the border box of the element to be scrolled
   into view with the left of the scrolling box.
   <!-- RTL is not special cased in implementations?! -->

   <li><p>If the aligning did not cause content to move terminate these
   steps.</li>

   <li>
    <dl>
     <dt>If the scrolling box is associated with an element</dt>
     <dd><p><a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#queue-a-task">Queue a task</a> to <a class="external" href="http://dom.spec.whatwg.org/#concept-event-fire" title="concept-event-fire">fire an event</a>
     named <code title="event-scroll">scroll</code> at the element
     associated with the scrolling box, unless a <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#concept-task" title="concept-task">task</a> to fire
     that event at that element was already
     <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#queue-a-task" title="queue a task">queued</a>.</dd>

     <dt>If the scrolling box is associated with a <a href="#viewport">viewport</a></dt>
     <dd><p><a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#queue-a-task">Queue a task</a> to <a class="external" href="http://dom.spec.whatwg.org/#concept-event-fire" title="concept-event-fire">fire an event</a>
     named <code title="event-scroll">scroll</code> that bubbles at the
     <code class="external"><a href="http://dom.spec.whatwg.org/#document">Document</a></code> object associated with the <a href="#viewport">viewport</a>,
     unless a <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#concept-task" title="concept-task">task</a> to fire that event at that
     <code class="external"><a href="http://dom.spec.whatwg.org/#document">Document</a></code> object was already
     <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#queue-a-task" title="queue a task">queued</a>.</dd>
    </dl>
   </li>
  </ol>

  <p>To <dfn id="scroll-an-element">scroll an element</dfn> to <var title="">x</var>,<var title="">y</var> means to:</p>

  <ol>
   <li>
    <dl>
     <dt>If the element can have overflow to the right</dt>

     <dd><p>Let <var title="">x</var> be max(0, min(<var title="">x</var>,
     <a href="#content">content</a> width -
     <a href="#content-edge">content edge</a> width)).</dd>

     <dt>If the element can have overflow to the left (under right-to-left
     conditions)</dt>

     <dd><p>Let <var title="">x</var> be min(0, max(<var title="">x</var>,
     <a href="#content-edge">content edge</a> width -
     <a href="#content">content</a> width)).</dd>
    </dl>
   </li>

   <li><p>Let <var title="">y</var> be max(0, min(<var title="">y</var>,
   <a href="#content">content</a> height - <a href="#content-edge">content edge</a> height)).</li>

   <li><p>Align <a href="#content">content</a> x-coordinate <var title="">x</var> with
   the left of the <a href="#content-edge">content edge</a> of the element and align
   <a href="#content">content</a> y-coordinate <var title="">y</var> with
   the top of the <a href="#content-edge">content edge</a> of the element.</li>

   <li><p>If the aligning caused content to move <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#queue-a-task">queue a task</a>
   to <a class="external" href="http://dom.spec.whatwg.org/#concept-event-fire" title="concept-event-fire">fire an event</a> named
   <code title="event-scroll">scroll</code> at the element, unless a
   <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#concept-task" title="concept-task">task</a> to fire that event at that element was already
   <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#queue-a-task" title="queue a task">queued</a>.</li>
  </ol>


  <h3 id="client-attributes"><span class="secno">6.3 </span>The <code title="">clientTop</code>,
  <code title="">clientLeft</code>, <code title="">clientWidth</code>, and
  <code title="">clientHeight</code> attributes</h3>

  <p>The <code title="widl-lElement-clientTop">clientTop</code>,
  <code title="widl-Element-clientLeft">clientLeft</code>,
  <code title="widl-Element-clientWidth">clientWidth</code>, and
  <code title="widl-Element-clientHeight">clientHeight</code>
  attributes must return zero if the element does not
  have any associated <a href="#css-layout-box">CSS layout box</a> or if the <a href="#css-layout-box">CSS layout box</a> is inline.
  Otherwise, these attributes must behave as defined in
  the remainder of this section.</p>

  <h2 id="extensions-to-the-htmlelement-interface"><span class="secno">7 </span>Extensions to the <code title="">HTMLElement</code> Interface</h2>


<pre class="idl"><span class="idlInterface" id="widl-def-HTMLElement">partial interface <span class="idlInterfaceID">HTMLElement</span> {
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>Element</a></span> <span class="idlAttrName"><a href="#widl-HTMLElement-offsetParent">offsetParent</a></span>;</span>
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>long</a></span> <span class="idlAttrName"><a href="#widl-HTMLElement-offsetTop">offsetTop</a></span>;</span>
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>long</a></span> <span class="idlAttrName"><a href="#widl-HTMLElement-offsetLeft">offsetLeft</a></span>;</span>
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>long</a></span> <span class="idlAttrName"><a href="#widl-HTMLElement-offsetWidth">offsetWidth</a></span>;</span>
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>long</a></span> <span class="idlAttrName"><a href="#widl-HTMLElement-offsetHeight">offsetHeight</a></span>;</span>
};</span></pre>
<dl class="attributes">
<dt class="attribute" id="widl-HTMLElement-offsetParent">
<dfn id="widl-HTMLElement-offsetParent"><code>offsetParent</code></dfn> of type <span class="idlAttrType"><a>Element</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-HTMLElement-offsetParent">offsetParent</a></code> attribute must return the result of running these steps:</p>    <ol>     <li>      <p>If any of the following holds true return null and terminate this      algorithm:</p>      <ul>       <li>The element does not have an associated <a href="#css-layout-box">CSS layout box</a>.</li>       <li>The element is the root element.</li>       <li>The element is <a href="#the-html-body-element">the HTML <code>body</code> element</a>.</li>       <li>The element's computed value of the '<code>position</code>' property is <code>fixed</code>.</li>      </ul>     </li>     <li>      <p>Return the nearest ancestor element of the element for which at least      one of the following is true and terminate this algorithm if such an      ancestor is found:</p>      <ul>       <li>The computed value of the '<code>position</code>' property is not <code>static</code>.</li>       <li>It is <a href="#the-html-body-element">the HTML <code>body</code> element</a>.</li>       <li>The computed value of the '<code>position</code>' property of       the element is <code>static</code> and the ancestor is one of the       following <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/infrastructure.html#html-elements" title="HTML elements">HTML elements</a>:       <code>td</code>, <code>th</code>, or <code>table</code>.</li>      </ul>     </li>     <li><p>Return null.</li>    </ol></dd>
<dt class="attribute" id="widl-HTMLElement-offsetTop">
<dfn id="widl-HTMLElement-offsetTop"><code>offsetTop</code></dfn> of type <span class="idlAttrType"><a>long</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-HTMLElement-offsetTop">offsetTop</a></code> attribute must return the result of running these steps:</p>    <ol>     <li><p>If the element is <a href="#the-html-body-element">the HTML <code>body</code> element</a>     or does not have any associated <a href="#css-layout-box">CSS layout box</a> return zero and terminate     this algorithm.</li>     <li><p>If the <code title="widl-HTMLElement-offsetParent">offsetParent</code> of the element is null return the     y-coordinate of the top <a href="#border-edge">border edge</a> of the first     <a href="#css-layout-box">CSS layout box</a> associated with the element, relative to the     <a href="#initial-containing-block">initial containing block</a> origin, and terminate this     algorithm.</li>     <li>      <p>Return the result of subtracting the y-coordinate of the top      <a href="#padding-edge">padding edge</a> of the first <a href="#css-layout-box">CSS layout box</a> associated with      the <code title="widl-HTMLElement-offsetParent">offsetParent</code> of the element from the y-coordinate of      the top <a href="#border-edge">border edge</a> of the first <a href="#css-layout-box">CSS layout box</a> associated      with the element, relative to the <a href="#initial-containing-block">initial containing block</a>      origin.</p>      <p class="note">An inline element that consists of multiple line boxes      will only have its first <a href="#css-layout-box">CSS layout box</a> considered.</p>     </li>    </ol></dd>
<dt class="attribute" id="widl-HTMLElement-offsetLeft">
<dfn id="widl-HTMLElement-offsetLeft"><code>offsetLeft</code></dfn> of type <span class="idlAttrType"><a>long</a></span>, readonly</dt>
<dd>
<p>The {@name{} attribute must return the result of running these steps:</p>    <ol>     <li><p>If the element is <a href="#the-html-body-element">the HTML <code>body</code>     element</a> or does not have any associated <a href="#css-layout-box">CSS layout box</a> return zero     and terminate this algorithm.</li>     <li><p>If the <code title="widl-HTMLElement-offsetParent">offsetParent</code> of the element is null return the     x-coordinate of the left <a href="#border-edge">border edge</a> of the first     <a href="#css-layout-box">CSS layout box</a> associated with the element, relative to the     <a href="#initial-containing-block">initial containing block</a> origin, and terminate this     algorithm.</li>     <li>      <p>Return the result of subtracting the x-coordinate of the left      <a href="#padding-edge">padding edge</a> of the first <a href="#css-layout-box">CSS layout box</a> associated with      the <code title="widl-HTMLElement-offsetParent">offsetParent</code> of the element from the x-coordinate of      the left <a href="#border-edge">border edge</a> of the first <a href="#css-layout-box">CSS layout box</a> associated      with the element, relative to the <a href="#initial-containing-block">initial containing block</a>      origin.</p>     </li>    </ol></dd>
<dt class="attribute" id="widl-HTMLElement-offsetWidth">
<dfn id="widl-HTMLElement-offsetWidth"><code>offsetWidth</code></dfn> of type <span class="idlAttrType"><a>long</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-HTMLElement-offsetWidth">offsetWidth</a></code> attribute must return the result of running these steps:</p>    <ol>     <li><p>If the element does not have any associated <a href="#css-layout-box">CSS layout box</a> return zero and terminate this algorithm.</li>     <li><p>Return the <a href="#border-edge">border edge</a> width of the first <a href="#css-layout-box">CSS layout box</a> associated with the element.</li>    </ol></dd>
<dt class="attribute" id="widl-HTMLElement-offsetHeight">
<dfn id="widl-HTMLElement-offsetHeight"><code>offsetHeight</code></dfn> of type <span class="idlAttrType"><a>long</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-HTMLElement-offsetHeight">offsetHeight</a></code> attribute must return the result of running these steps:</p>    <ol>     <li><p>If the element does not have any associated <a href="#css-layout-box">CSS layout box</a> return zero and terminate this algorithm.</li>     <li><p>Return the <a href="#border-edge">border edge</a> height of the first <a href="#css-layout-box">CSS layout box</a> associated with the element.</li>    </ol></dd>
</dl>


  <h2 id="extensions-to-the-range-interface"><span class="secno">8 </span>Extensions to the <code title="">Range</code> Interface</h2>

  <p>The objects the methods described below return must
  be static.</p>


<pre class="idl"><span class="idlInterface" id="widl-def-Range">partial interface <span class="idlInterfaceID">Range</span> {
<span class="idlMethod">    <span class="idlMethType"><a>ClientRectList</a></span> <span class="idlMethName"><a href="#widl-Range-getClientRects-ClientRectList">getClientRects</a></span> ();</span>
<span class="idlMethod">    <span class="idlMethType"><a>ClientRect</a></span> <span class="idlMethName"><a href="#widl-Range-getBoundingClientRect-ClientRect">getBoundingClientRect</a></span> ();</span>
};</span></pre>
<dl class="methods">
<dt class="method" id="widl-Range-getClientRects-ClientRectList">
<dfn id="widl-Range-getClientRects"><code>getClientRects</code></dfn> (), returns <span class="idlMethType"><a>ClientRectList</a></span></dt>
<dd>
<p>The <code><a href="#widl-Range-getClientRects">getClientRects</a></code> operation, when invoked, must return an empty    <code>ClientRectList</code> object if the range is not in the document and    otherwise a <code>ClientRectList</code> object containing a list of    <code>ClientRect</code> objects in content order that matches the    following constraints:</p>    <ul>     <li>For each element selected by the range, whose parent is not selected     by the range, include the border boxes returned by invoking     <code title="widl-Element-getClientRects">getClientRects()</code> on the     element.</li>     <li>For each <code>Text</code> node selected or partially selected by the     range (including when the boundary-points are identical), include a     <code>ClientRect</code> object (for the part that is selected, not the     whole line box). The bounds of these <code>ClientRect</code> objects are     computed using font metrics; thus, for horizontal writing, the vertical     dimension of each box is determined by the font ascent and descent, and     the horizontal dimension by the text advance width.</li>    </ul></dd>
<dt class="method" id="widl-Range-getBoundingClientRect-ClientRect">
<dfn id="widl-Range-getBoundingClientRect"><code>getBoundingClientRect</code></dfn> (), returns <span class="idlMethType"><a>ClientRect</a></span></dt>
<dd>
<p>The <code><a href="#widl-Range-getBoundingClientRect">getBoundingClientRect</a></code> operation, when invoked, must return the result of the following algorithm:</p>    <ol>     <li><p>Let <var>list</var> be the result of invoking     <code title="widl-Range-getClientRects">getClientRects()</code> on the     same range this method was invoked on.</li>     <li><p>If <var>list</var> is empty return a     <code>ClientRect</code> object whose     <code title="widl-ClientRect-top">top</code>,     <code title="widl-ClientRect-right">right</code>,     <code title="widl-ClientRect-bottom">bottom</code> and     <code title="widl-ClientRect-left">left</code> members are zero.</li>     <li><p>Otherwise, return a <code>ClientRect</code> object describing the     smallest rectangle that includes the first rectangle in <var>list</var>     and all of the remaining rectangles of which the height or width is not     zero.</li>    </ol></dd>
</dl>


  <h2 id="extensions-to-the-mouseevent-interface"><span class="secno">9 </span>Extensions to the <code title="">MouseEvent</code> Interface</h2>

  <p class="issue">The object IDL fragment redefines some members. Can we
  resolve this somehow?</p>

  <!-- x/y do not match IE in the position:relative case but do match other
  browsers -->


<pre class="idl"><span class="idlInterface" id="widl-def-MouseEvent">partial interface <a class="idlInterfaceID" href="#mouseevent">MouseEvent</a> {
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>long</a></span> <span class="idlAttrName"><a href="#widl-MouseEvent-screenX">screenX</a></span>;</span>
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>long</a></span> <span class="idlAttrName"><a href="#widl-MouseEvent-screenY">screenY</a></span>;</span>
<span
E88C
 class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>long</a></span> <span class="idlAttrName"><a href="#widl-MouseEvent-pageX">pageX</a></span>;</span>
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>long</a></span> <span class="idlAttrName"><a href="#widl-MouseEvent-pageY">pageY</a></span>;</span>
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>long</a></span> <span class="idlAttrName"><a href="#widl-MouseEvent-clientX">clientX</a></span>;</span>
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>long</a></span> <span class="idlAttrName"><a href="#widl-MouseEvent-clientY">clientY</a></span>;</span>
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>long</a></span> <span class="idlAttrName"><a href="#widl-MouseEvent-x">x</a></span>;</span>
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>long</a></span> <span class="idlAttrName"><a href="#widl-MouseEvent-y">y</a></span>;</span>
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>long</a></span> <span class="idlAttrName"><a href="#widl-MouseEvent-offsetX">offsetX</a></span>;</span>
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>long</a></span> <span class="idlAttrName"><a href="#widl-MouseEvent-offsetY">offsetY</a></span>;</span>
};</span></pre>
<dl class="attributes">
<dt class="attribute" id="widl-MouseEvent-screenX">
<dfn id="widl-MouseEvent-screenX"><code>screenX</code></dfn> of type <span class="idlAttrType"><a>long</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-MouseEvent-screenX">screenX</a></code> attribute must return the x-coordinate of    the position where the event occurred relative to the origin of the    screen.</dd>
<dt class="attribute" id="widl-MouseEvent-screenY">
<dfn id="widl-MouseEvent-screenY"><code>screenY</code></dfn> of type <span class="idlAttrType"><a>long</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-MouseEvent-screenY">screenY</a></code> attribute must return the y-coordinate of    the position where the event occurred relative to the origin of the    screen.</dd>
<dt class="attribute" id="widl-MouseEvent-pageX">
<dfn id="widl-MouseEvent-pageX"><code>pageX</code></dfn> of type <span class="idlAttrType"><a>long</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-MouseEvent-pageX">pageX</a></code> attribute must return the horizontal coordinate of    the position where the event occurred relative to    the origin of the <a href="#initial-containing-block">initial containing block</a>.</dd>
<dt class="attribute" id="widl-MouseEvent-pageY">
<dfn id="widl-MouseEvent-pageY"><code>pageY</code></dfn> of type <span class="idlAttrType"><a>long</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-MouseEvent-pageY">pageY</a></code> attribute must return the y-coordinate of the    position where the event occurred relative to the origin of the    <a href="#initial-containing-block">initial containing block</a>.</dd>
<dt class="attribute" id="widl-MouseEvent-clientX">
<dfn id="widl-MouseEvent-clientX"><code>clientX</code></dfn> of type <span class="idlAttrType"><a>long</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-MouseEvent-clientX">clientX</a></code> attribute must return the x-coordinate of    the position where the event occurred relative to the origin of the    <a href="#viewport">viewport</a>.</dd>
<dt class="attribute" id="widl-MouseEvent-clientY">
<dfn id="widl-MouseEvent-clientY"><code>clientY</code></dfn> of type <span class="idlAttrType"><a>long</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-MouseEvent-clientY">clientY</a></code> attribute must return the y-coordinate of    the position where the event occurred relative to the origin of the    <a href="#viewport">viewport</a>.</dd>
<dt class="attribute" id="widl-MouseEvent-x">
<dfn id="widl-MouseEvent-x"><code>x</code></dfn> of type <span class="idlAttrType"><a>long</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-MouseEvent-x">x</a></code> attribute must return the value of <code title="widl-MouseEvent-clientX">clientX</code>.</dd>
<dt class="attribute" id="widl-MouseEvent-y">
<dfn id="widl-MouseEvent-y"><code>y</code></dfn> of type <span class="idlAttrType"><a>long</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-MouseEvent-y">y</a></code> attribute must return the value of <code title="widl-MouseEvent-clientY">clientY</code>.</dd>
<dt class="attribute" id="widl-MouseEvent-offsetX">
<dfn id="widl-MouseEvent-offsetX"><code>offsetX</code></dfn> of type <span class="idlAttrType"><a>long</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-MouseEvent-offsetX">offsetX</a></code> attribute must return the x-coordinate of    the position where the event occurred relative to the origin of the    <a href="#padding-edge">padding edge</a> of the target node.</dd>
<dt class="attribute" id="widl-MouseEvent-offsetY">
<dfn id="widl-MouseEvent-offsetY"><code>offsetY</code></dfn> of type <span class="idlAttrType"><a>long</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-MouseEvent-offsetY">offsetY</a></code> attribute must return the y-coordinate of    the position where the event occurred relative to the origin of the    <a href="#padding-edge">padding edge</a> of the target node.</dd>
</dl>


  <h2 id="rectangles"><span class="secno">10 </span>Rectangles</h2>


  <h3 id="the-clientrectlist-interface"><span class="secno">10.1 </span>The <code title="">ClientRectList</code> Interface</h3>

  <p>The <code>ClientRectList</code> interface consists of an ordered list of <code>ClientRect</code> objects.</p>
<pre class="idl"><span class="idlInterface" id="widl-def-ClientRectList">interface <span class="idlInterfaceID">ClientRectList</span> {
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>unsigned long</a></span> <span class="idlAttrName"><a href="#widl-ClientRectList-length">length</a></span>;</span>
<span class="idlMethod">    <span class="idlMethType"><a>ClientRect</a></span> <span class="idlMethName"><a href="#widl-ClientRectList-item-ClientRect-unsigned-long-index">item</a></span> (<span class="idlParam"><span class="idlParamType"><a>unsigned long</a></span> <span class="idlParamName">index</span></span>);</span>
};</span></pre>
<dl class="attributes">
<dt class="attribute" id="widl-ClientRectList-length">
<dfn id="widl-ClientRectList-length"><code>length</code></dfn> of type <span class="idlAttrType"><a>unsigned long</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-ClientRectList-length">length</a></code> attribute must return the total number of <code>ClientRect</code> objects associated with the object.</dd>
</dl>
<dl class="methods">
<dt class="method" id="widl-ClientRectList-item-ClientRect-unsigned-long-index">
<dfn id="widl-ClientRectList-item"><code>item</code></dfn> (<span class="idlParam"><span class="idlParamType"><a>unsigned long</a></span> <span class="idlParamName">index</span></span>), returns <span class="idlMethType"><a>ClientRect</a></span></dt>
<dd>
<p>The <code><a href="#widl-ClientRectList-item">item</a></code> operation, when invoked, must raise an <code>INDEX_SIZE_ERR</code> exception when <var title="">index</var> is    greater than the number of <code>ClientRect</code> objects associated with the object. Otherwise, the <code>ClientRect</code> object at    <var title="">index</var> must be returned.</dd>
</dl>


  <h3 id="the-clientrect-interface"><span class="secno">10.2 </span>The <code title="">ClientRect</code> Interface</h3>

  <p>Objects implementing the <code>ClientRect</code> interface represent a rectangular box. The type of box is specified by the method that returns a <code>ClientRect</code> interface.</p>
<pre class="idl"><span class="idlInterface" id="widl-def-ClientRect">interface <span class="idlInterfaceID">ClientRect</span> {
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>float</a></span> <span class="idlAttrName"><a href="#widl-ClientRect-top">top</a></span>;</span>
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>float</a></span> <span class="idlAttrName"><a href="#widl-ClientRect-right">right</a></span>;</span>
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>float</a></span> <span class="idlAttrName"><a href="#widl-ClientRect-bottom">bottom</a></span>;</span>
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>float</a></span> <span class="idlAttrName"><a href="#widl-ClientRect-left">left</a></span>;</span>
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>float</a></span> <span class="idlAttrName"><a href="#widl-ClientRect-width">width</a></span>;</span>
<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>float</a></span> <span class="idlAttrName"><a href="#widl-ClientRect-height">height</a></span>;</span>
};</span></pre>
<dl class="attributes">
<dt class="attribute" id="widl-ClientRect-top">
<dfn id="widl-ClientRect-top"><code>top</code></dfn> of type <span class="idlAttrType"><a>float</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-ClientRect-top">top</a></code> attribute must return the y-coordinate, relative to the <a href="#viewport">viewport</a> origin, of the top of the rectangle box.</dd>
<dt class="attribute" id="widl-ClientRect-right">
<dfn id="widl-ClientRect-right"><code>right</code></dfn> of type <span class="idlAttrType"><a>float</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-ClientRect-right">right</a></code> attribute must return the x-coordinate, relative to the <a href="#viewport">viewport</a> origin, of the right of the rectangle box.</dd>
<dt class="attribute" id="widl-ClientRect-bottom">
<dfn id="widl-ClientRect-bottom"><code>bottom</code></dfn> of type <span class="idlAttrType"><a>float</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-ClientRect-bottom">bottom</a></code> attribute must return the y-coordinate, relative to the <a href="#viewport">viewport</a> origin, of the bottom of the rectangle box.</dd>
<dt class="attribute" id="widl-ClientRect-left">
<dfn id="widl-ClientRect-left"><code>left</code></dfn> of type <span class="idlAttrType"><a>float</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-ClientRect-left">left</a></code> attribute must return the x-coordinate, relative to the <a href="#viewport">viewport</a> origin, of the left of the rectangle box.</dd>
<dt class="attribute" id="widl-ClientRect-width">
<dfn id="widl-ClientRect-width"><code>width</code></dfn> of type <span class="idlAttrType"><a>float</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-ClientRect-width">width</a></code> attribute must return the width of the rectangle box.</p>    <p class="note">This is identical to <code title="widl-ClientRect-right">right</code> minus <code title="widl-ClientRect-left">left</code>.</dd>
<dt class="attribute" id="widl-ClientRect-height">
<dfn id="widl-ClientRect-height"><code>height</code></dfn> of type <span class="idlAttrType"><a>float</a></span>, readonly</dt>
<dd>
<p>The <code><a href="#widl-ClientRect-height">height</a></code> attribute must return the height of the rectangle box.</p>    <p class="note">This is identical to <code title="widl-ClientRect-bottom">bottom</code> minus <code title="widl-ClientRect-top">top</code>.</dd>
</dl>


<h2 class="no-num" id="references">References</h2>
<h3 class="no-num" id="normative-references">Normative references</h3>
<div id="anolis-references-normative"><dl><dt id="refsCSSOM">[CSSOM]
<dd><cite><a href="http://dev.w3.org/csswg/cssom/">CSS Object Model (CSSOM)</a></cite>, Glenn Adams and Simon Pieters. W3C.

<dt id="refsDOM">[DOM]
<dd><cite><a href="http://dom.spec.whatwg.org/">DOM</a></cite>, Anne van Kesteren, Aryeh Gregor and Ms2ger. WHATWG.

<dt id="refsHTML">[HTML]
<dd><cite><a href="http://www.whatwg.org/specs/web-apps/current-work/multipage/">HTML</a></cite>, Ian Hickson. WHATWG.

<dt id="refsRFC2119">[RFC2119]
<dd><cite><a href="http://tools.ietf.org/html/rfc2119">Key words for use in RFCs to Indicate Requirement Levels</a></cite>, Scott Bradner. IETF.

<dt id="refsSVG">[SVG]
<dd><cite><a href="http://www.w3.org/TR/SVG/">Scalable Vector Graphics (SVG)</a></cite>, O. Andersson, R. Berjon, E. Dahlström et al.. W3C.

<dt id="refsWEBIDL">[WEBIDL]
<dd><cite><a href="http://dev.w3.org/2006/webapi/WebIDL/">Web IDL</a></cite>, Cameron McCormack. W3C.

</dl></div>


<!--
<h3 class=no-num>Informative references</h3>
<div id=anolis-references-informative></div>
-->


  <h2 class="no-num" id="acknowledgments">Acknowledgments</h2>

  <p>The editors would like to thank

  Alexey Feldgendler,
  Björn Höhrmann,
  Dan Bates,
  David Vest,
  Garrett Smith,
  Hallvord R. M. Steen,
  Leif Arne Storset,
  Luiz Agostini,
  Maciej Stachowiak,
  Michael Dyck,
  Mike Wilson,
  Morten Stenshorne,
  Peter-Paul Koch,
  Rachel Kmetz,
  Robert O'Callahan,
  Sam Weinig,
  <!--Simon Pieters,-->
  Scott Johnson,
  Sylvain Galineau,
  Tarquin Wilton-Jones,
  Thomas Moore, and
  Xiaomei Ji<!-- should actually use real name here -->

  for their contributions to this document.</p>

  <p>Special thanks to the Microsoft employees who first implemented many of
  the features specified in this draft, which were first widely deployed by
  the Windows Internet Explorer browser.</p>