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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN">
<html lang="en-US">
<head>
<title>CSSOM View Module</title>
<style type="text/css">
pre.idl { border:solid thin; background:#eee; color:#000; padding:0.5em }
pre.idl :link, pre.idl :visited { color:inherit; background:transparent }
dfn { font-weight:bold; font-style:normal }
div.example { margin-left:1em; padding-left:1em; border-left:double; color:#222; background:#fcfcfc }
div.example code { color:inherit }
p.note { margin-left:2em; color:green; font-style:italic; font-weight:bold }
p.note::before { content:"Note: " }
.XXX { padding:.5em; border:solid red }
.XXX::before { content:"Issue: " }
em.ct { font-weight:bold; font-style:normal }
code { color:orangered }
code :link, code :visited { color:inherit }
</style>
<link rel="stylesheet" href="http://www.w3.org/StyleSheets/TR/W3C-[STATUS]">
</head>
<body class="draft">
<div class="head">
<!--logo-->
<h1 id="cssom-view-module">CSSOM View Module</h1>
<h2 class="no-num no-toc" id="w3c-doctype">[LONGSTATUS] [DATE: 3 August 2002]</h2>
<dl>
<dt>This Version:</dt>
<dd><a href="[VERSION]/">http://www.w3.org/TR/[YEAR]/ED-cssom-view-[CDATE]/</a></dd>
<dt>Latest Version:</dt>
<dd><a href="http://www.w3.org/TR/cssom-view/">http://www.w3.org/TR/cssom-view/</a></dd>
<dt>Latest Editor Version:</dt>
<dd><a href="http://dev.w3.org/csswg/cssom-view/">http://dev.w3.org/csswg/cssom-view/</a></dd>
<dt>Previous Versions:</dt>
<dd><a href="http://www.w3.org/TR/2009/WD-cssom-view-20090804/">http://www.w3.org/TR/2009/WD-cssom-view-20090804/</a></dd>
<dd><a href="http://www.w3.org/TR/2008/WD-cssom-view-20080222/">http://www.w3.org/TR/2008/WD-cssom-view-20080222/</a></dd>
<dt>Editor:</dt>
<dd><a href="http://annevankesteren.nl/">Anne van Kesteren</a>
(<a href="http://www.opera.com/">Opera Software ASA</a>)
<<a href="mailto:annevk@opera.com">annevk@opera.com</a>></dd>
</dl>
<!-- copyright -->
</div>
<hr>
<h2 id="abstract" class="no-num no-toc">Abstract</h2>
<p>The APIs introduced by this specification provide authors with a way to
inspect and manipulate the visual view of a document. This includes
getting the position of element layout boxes, obtaining the width
of the viewport through script, and also scrolling an element.</p>
<h2 id="sotd" class="no-num no-toc">Status of this Document</h2>
<!-- status -->
<h2 id="toc" class="no-num no-toc">Table of Contents</h2>
<!-- toc -->
<h2 id="background">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">Conformance Criteria</h2>
<p>Everything in this specification is normative except for diagrams,
examples, notes and sections marked non-normative.</p>
<!--<p>The key word <em class="ct">must</em>, <em class="ct">must not</em>,
<em class="ct">should</em> and <em class="ct">may</em> in this document
are to be interpreted as described in RFC 2119.-->
<p>The key word <em class="ct">must</em> in this document is to be
interpreted as described in RFC 2119.
[<cite><span>RFC2119</span></cite>]</p>
<p>A conforming user agent implements all the requirements made by this
specification.</p>
<h3 id="webidl">Web IDL</h3>
<p>The IDL fragments in this specification <em class="ct">must</em> be
interpreted as required for conforming IDL fragments, as described in the
Web IDL specification. [<cite><span>WebIDL</span></cite>]</p>
<h3 id="terminology">Terminology</h3>
<p><dfn><code>Document</code></dfn> and <dfn><code>Element</code></dfn>
are defined by DOM Level 3 Core. [<cite><span>DOM3Core</span></cite>]</p>
<p><dfn><code>Range</code></dfn> is defined in
DOM Level 2 Traversal and Range. [<cite><span>DOM2TR</span></cite>]</p>
<p><dfn><code>MouseEvent</code></dfn> is defined in DOM Level 2 Events.
[<cite><span>DOM2Events</span></cite>]</p>
<p>
<dfn>Serialize a media query list</dfn> and
<dfn>parse a media query list</dfn>
are defined by the CSSOM. [<cite><span>CSSOM</span></cite>]</p>
<p>
<dfn id="fire-a-simple-event" title="Fire a simple event">Firing a simple event named <var title="">e</var></dfn>,
<dfn>HTML element</dfn>,
<dfn><code>HTMLElement</code></dfn>,
<dfn>queue a task</dfn>,
<dfn>quirks mode</dfn>,
<dfn>same origin</dfn>,
<dfn>task</dfn>, and
<dfn><code>Window</code></dfn>
are defined by HTML5. [<cite><span>HTML5</span></cite>]</p>
<p><dfn>The HTML <code>body</code> element</dfn> is the first
<code>body</code> <span>HTML element</span> child of the root
<span>HTML element</span> <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 2.1.
[<cite><span>CSS21</span></cite>]</p>
<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.
[<cite><span>CSS21</span></cite>]
[<cite><span>SVG</span></cite>]</p>
<p>The term <dfn>content</dfn> refers to the dimensions of the element's
content area, including overflown content.
[<cite><span>CSS21</span></cite>]</p>
<p>The term <dfn>document content</dfn> refers to the area on the
<span>canvas</span> that is rendered upon, excluding content on negative
axis.</p>
<h3>CSS pixels</h3>
<p>All coordinates and dimensions for the APIs defined in this
specification are in CSS pixels. [<cite><span>CSS21</span></cite>]</p>
<p class="note">This does not apply to e.g.
<code title="dom-Window-matchMedia">matchMedia()</code> as the units
are explicitly given there.</p>
<h2 id="extensions-to-the-window-interface">Extensions to the <code title="">Window</code> Interface</h2>
<pre class="idl">[Supplemental] interface <span>Window</span> {
<span>MediaQueryList</span> <span title="dom-Window-matchMedia">matchMedia</span>(DOMString <var title="">media_query_list</var>);
readonly attribute <span>Screen</span> <span title="dom-Window-screen">screen</span>;
// viewport
readonly attribute long <span>innerWidth</span>;
readonly attribute long <span>innerHeight</span>;
// viewport scrolling
readonly attribute long <span title="dom-Window-scrollX">scrollX</span>;
readonly attribute long <span title="dom-Window-pageXOffset">pageXOffset</span>;
readonly attribute long <span title="dom-Window-scrollY">scrollY</span>;
readonly attribute long <span title="dom-Window-pageYOffset">pageYOffset</span>;
void <span title="dom-Window-scroll">scroll</span>(long <var title="">x</var>, long <var title="">y</var>);
void <span title="dom-Window-scrollto">scrollTo</span>(long <var title="">x</var>, long <var title="">y</var>);
void <span title="dom-Window-scrollby">scrollBy</span>(long <var title="">x</var>, long <var title="">y</var>);
// client
readonly attribute long <span>screenX</span>;
readonly attribute long <span>screenY</span>;
readonly attribute long <span>outerWidth</span>;
readonly attribute long <span>outerHeight</span>;
};</pre>
<p>When the
<dfn id="dom-window-matchmedia" title="dom-Window-matchMedia"><code>matchMedia(<var title="">media_query_list</var>)</code></dfn>
method is invoked these steps must be run:</p>
<ol>
<li><p>Let <var title="">parsed_media_query_list</var> be the result of
<span title="parse a media query list">parsing</span>
<var title="">media_query_list</var>.</p></li>
<li><p>Return a <em>new</em> <code>MediaQueryList</code> object,
associated with the <code>Window</code> object, with
<var title="">parsed_media_query_list</var> as its associated
media query list.</p></li>
</ol>
<p>The
<dfn id="dom-window-screen" title="dom-Window-screen"><code>screen</code></dfn>
attribute <em class="ct">must</em> return the <code>Screen</code> object
associated with the <code>Window</code> object. It always returns the same
object.</p>
<p class="note">Accessing <code title="dom-Window-screen">screen</code> through a <code>WindowProxy</code> object might yield different results
when the <code>Document</code> is navigated.</p>
<p>The <dfn id="dom-window-innerwidth"><code>innerWidth</code></dfn>
attribute <em class="ct">must</em> return the
<span>viewport</span> 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>
<p>The <dfn id="dom-window-innerheight"><code>innerHeight</code></dfn>
attribute <em class="ct">must</em> return the
<span>viewport</span> height including the size of a rendered scroll bar
(if any).</p>
<p>The
<dfn id="dom-window-scrollx" title="dom-Window-scrollX"><code>scrollX</code></dfn> and
<dfn id="dom-window-pagexoffset" title="dom-Window-pageXOffset"><code>pageXOffset</code></dfn>
attributes <em class="ct">must</em> return the x-coordinate,
relative to the <span>initial containing block</span> origin, of the left
of the <span>viewport</span>.</p>
<p>The
<dfn id="dom-window-scrolly" title="dom-Window-scrollY"><code>scrollY</code></dfn> and
<dfn id="dom-window-pageyoffset" title="dom-Window-pageYOffset"><code>pageYOffset</code></dfn>
attributes <em class="ct">must</em> return the y-coordinate,
relative to the <span>initial containing block</span> origin, of the top
of the <span>viewport</span>.</p>
<p>When the
<dfn id="dom-window-scroll" title="dom-Window-scroll"><code>scroll(<var title="">x</var>,<var title="">y</var>)</code></dfn>
method is invoked these steps <em class="ct">must</em> be run:</p>
<ol>
<li><p>If either <var title="">x</var> or <var title="">y</var> is
infinite or NaN terminate this algorithm.</p></li>
<li>
<dl>
<dt>If <span>document content</span> can have overflow to the right
<dd><p>Let <var title="">x</var> be max(0, min(<var title="">x</var>,
<span>content</span> width - <span>content edge</span>
width)).</p></dd>
<dt>If <span>document content</span> 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>,
<span>content edge</span> width - <span>content</span>
width)).</p></dd>
</dl>
<li><p>Let <var title="">y</var> be max(0, min(<var title="">y</var>,
<span>document content</span> height - <span>viewport</span>
height excluding the size of a rendered scroll bar (if any))).</p></li>
<li><p>Align the x-coordinate <var title="">x</var> of the
<span>document content</span> with the left of the <span>viewport</span>
and align the y-coordinate <var title="">y</var> of the <span>document
content</span> with the top of the <span>viewport</span>.</p></li>
<li><p>If the aligning caused content to move <span>queue a task</span>
to <span>fire a simple event</span> named
<code title="event-scroll">scroll</code> that bubbles at the
<code>Document</code> object, unless a
<span>task</span> to fire that event at the <code>Document</code> object
was already <span title="queue a task">queued</span>.</p></li>
</ol>
<p>When the
<dfn id="dom-window-scrollto" title="dom-Window-scrollto"><code>scrollTo(<var title="">x</var>,<var title="">y</var>)</code></dfn>
method is invoked, the user agent <em class="ct">must</em> act as if the
<code title="dom-Window-scroll">scroll()</code> method was invoked with
the same arguments.</p>
<p>When the
<dfn id="dom-window-scrollby" title="dom-Window-scrollby"><code>scrollBy(<var title="">x</var>,<var title="">y</var>)</code></dfn>
method is invoked, the user agent <em class="ct">must</em> act as if the
<code title="dom-Window-scroll">scroll()</code> method was invoked with
<var title="">x</var> plus <code title="dom-Window-scrollX">scrollX</code>
as first argument and <var title="">y</var> plus
<code title="dom-Window-scrollY">scrollY</code> as second argument.</p>
<p>The <dfn id="dom-window-screenx"><code>screenX</code></dfn>
attribute <em class="ct">must</em> return the x-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.</p>
<p>The <dfn id="dom-window-screeny"><code>screenY</code></dfn>
attribute <em class="ct">must</em> return the y-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.</p>
<p>The <dfn id="dom-window-outerwidth"><code>outerWidth</code></dfn>
attribute <em class="ct">must</em> return the width of the
client window. If there is no client window this
attribute <em class="ct">must</em> return zero.</p>
<p>The <dfn id="dom-window-outerheight"><code>outerHeight</code></dfn>
attribute <em class="ct">must</em> return the height of the
client window. If there is no client window
this attribute <em class="ct">must</em> return zero.</p>
<h3 id="the-mediaquerylist-interface">The <code title="">MediaQueryList</code> Interface</h3>
<p>A <code>MediaQueryList</code> object has an associated media query list
set on creation and an associated
<dfn>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 <span>list of media query list listeners</span> — in
appending order, <span>queue a task</span> 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">interface <dfn id="mediaquerylist">MediaQueryList</dfn> {
readonly attribute DOMString <span title="dom-MediaQueryList-media">media</span>;
readonly attribute DOMString <span title="dom-MediaQueryList-matches">matches</span>;
void <span title="dom-MediaQueryList-addListener">addListener</span>(<span>MediaQueryListListener</span> <var title="">listener</var>);
void <span title="dom-MediaQueryList-removeListener">removeListener</span>(<span>MediaQueryListListener</span> <var title="">listener</var>);
};
[Callback=FunctionOnly, NoInterfaceObject]
interface <dfn id="mediaquerylistlistener">MediaQueryListListener</dfn> {
void <span>handleChange</span>(<span>MediaQueryList</span> <var title="">mql</var>);
};</pre>
<p>The
<dfn id="dom-MediaQueryList-media" title="dom-MediaQueryList-media"><code>media</code></dfn>
<em class="ct">must</em> return the
<span title="serialize a media query list">serialized</span> form of the associated media query list.</p>
<p>The
<dfn id="dom-MediaQueryList-matches" title="dom-MediaQueryList-matches"><code>matches</code></dfn>
<em class="ct">must</em> return true if the associated media query list
matches the state of the rendered <code>Document</code> and false if it
does not.</p>
<p>When the
<dfn id="dom-mediaquerylist-addlistener" title="dom-MediaQueryList-addListener"><code>addListener(<var title="">listener</var>)</code></dfn>
is invoked <var title="">listener</var> <em class="ct">must</em> be
appended to the <span>list of media query list listeners</span>, unless
it is already in the <span>list of media query list listeners</span>.</p>
<p>When the
<dfn id="dom-mediaquerylist-removelistener" title="dom-MediaQueryList-removeListener"><code>removeListener(<var title="">listener</var>)</code></dfn>
is invoked <var title="">listener</var> <e class="ct">must</em> be removed
from the <span>list of media query list listeners</span>.</p>
<h3 id="the-screen-interface">The <code title="">Screen</code> Interface</h3>
<p>As its name suggests, the <code>Screen</code> interface represents
information about the screen of the output device.</p>
<pre class="idl">interface <dfn id="screen">Screen</dfn> {
readonly attribute unsigned long <span>availWidth</span>;
readonly attribute unsigned long <span>availHeight</span>;
readonly attribute unsigned long <span>width</span>;
readonly attribute unsigned long <span>height</span>;
readonly attribute unsigned long <span>colorDepth</span>;
readonly attribute unsigned long <span>pixelDepth</span>;
};</pre>
<p>The <dfn id="dom-screen-availwidth"><code>availWidth</code></dfn>
attribute <em class="ct">must</em> return the available width of the
rendering surface of the output device.</p>
<p>The <dfn id="dom-screen-availheight"><code>availHeight</code></dfn>
attribute <em class="ct">must</em> return the available height of the
rendering surface of the output device.</p>
<p>The <dfn id="dom-screen-width"><code>width</code></dfn> attribute
<em class="ct">must</em> return the width of the output device.</p>
<p>The <dfn id="dom-screen-height"><code>height</code></dfn> attribute
<em class="ct">must</em> return the height of the output device.</p>
<p>The <dfn id="dom-screen-colordepth"><code>colorDepth</code></dfn> and
<dfn id="dom-screen-pixeldepth"><code>pixelDepth</code></dfn> attributes
<em class="ct">must</em> both 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
<em class="ct">must</em> return zero.</p>
<!-- pixelDepth is not supported by Internet Explorer 7 -->
<h2 id="extensions-to-the-document-interface">Extensions to the <code title="">Document</code> Interface</h2>
<pre class="idl">[Supplemental] interface <span>Document</span> {
Element <span>elementFromPoint</span>(float <var title="">x</var>, float <var title="">y</var>);
<span>CaretPosition</span> <span>caretPositionFromPoint</span>(float <var title="">x</var>, float <var title="">y</var>);
};</pre>
<p>The
<dfn id="dom-document-elementfrompoint" title="elementfrompoint"><code>elementFromPoint(<var title="">x</var>,
<var title="">y</var>)</code></dfn> method, when invoked,
<em class="ct">must</em> return the element at coordinates
<var>x</var>,<var>y</var> in the <span>viewport</span>. The element to be
returned is determined through hit testing. If either argument is
negative, <var title="">x</var> is greater than the <span>viewport</span>
width excluding the size of a rendered scroll bar (if any), or
<var title="">y</var> is greather than the <span>viewport</span> height
excluding the size of a rendered scroll bar (if any), the method
<em class="ct">must</em> return <code>null</code>. If there is no element
at the given position the method <em class="ct">must</em> return the root
element, if any, or <code>null</code> otherwise.</p>
<p>The
<dfn id="dom-document-caretpositionfrompoint" title="caretpositionfrompoint"><code>caretPositionFromPoint(<var title="">x</var>,
<var title="">y</var>)</code></dfn> method, when invoked,
<em class="ct">must</em> return the result of running these steps:</p>
<ol>
<li><p>If either argument is negative, <var title="">x</var> is greater
than the <span>viewport</span> width excluding the size of a rendered
scroll bar (if any), <var title="">y</var> is greather than the
<span>viewport</span> height excluding the size of a rendered scroll bar
(if any) return null.</p></li>
<li><p>If at the coordinates <var title="">x</var>,<var title="">y</var>
in the <span>viewport</span> no text insertion point indicator would have
been inserted return null.</p></li>
<li>
<p>If at the coordinates <var title="">x</var>,<var title="">y</var>
in the <span>viewport</span> a text insertion point indicator would have
been inserted in a text entry widget which is also a replaced element
return a <span>caret position</span> with its properties set as
follows:</p>
<dl>
<dt><span>caret node</span></dt>
<dd><p>The node corresponding to the text entry widget.</p></dd>
<dt><span>caret offset</span></dt>
<dd><p>The amount of 16-bit units to the left of where the
text insertion point indicator would have inserted.</p></dd>
<dt><span>caret range</span></dt>
<dd><p>null</p></dd>
</dl>
</li>
<li>
<p>Otherwise, return a <span>caret position</span> where the
<span>caret range</span> is a collapsed <code>Range</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><span>caret node</span></dt>
<dd><p>The <code title="dom-Range-startContainer">startContainer</code>
of the <span>caret range</span>.</p></dd>
<dt><span>caret offset</span></dt>
<dd><p>The <code title="dom-Range-startOffset">startOffset</code> of
the <span>caret range</span>.</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>elementFromPoint()</code> and <code>caretPositionFromPoint()</code>
are therefore too. Hit testing will hopefully be defined in a future
revision of CSS or HTML.</p>
<h3 id="the-caretposition-interface">The <code title="">CaretPosition</code> Interface</h3>
<p>A <dfn>caret position</dfn> gives the position of a
text insertion point indicator. It always has an associated
<dfn>caret node</dfn>, <dfn>caret offset</dfn>, and
<dfn>caret range</dfn>. It is represented by a <code>CaretPosition</code>
object.</p>
<pre class="idl">interface <dfn id="caretposition">CaretPosition</dfn> {
readonly attribute <span>Node</span> <span title="dom-CaretPosition-offsetNode">offsetNode</span>;
readonly attribute unsigned long <span title="dom-CaretPosition-offset">offset</span>;
readonly attribute <span>Range</span> <span title="dom-CaretPosition-range">range</span>;
};</pre>
<p>The
<dfn id="dom-caretposition-offsetnode" title="dom-CaretPosition-offsetNode"><code>offsetNode</code></dfn>
attribute <em class="ct">must</em> return the <span>caret node</span>.</p>
<p>The
<dfn id="dom-caretposition-offset" title="dom-CaretPosition-offset"><code>offset</code></dfn>
attribute <em class="ct">must</em> return the <span>caret offset</span>.</p>
<p>The
<dfn id="dom-caretposition-range" title="dom-CaretPosition-range"><code>range</code></dfn>
attribute <em class="ct">must</em> return the <span>caret range</span>.</p>
<!-- https://bugs.webkit.org/show_bug.cgi?id=27046 -->
<h2 id="extensions-to-the-element-interface">Extensions to the <code title="">Element</code> Interface</h2>
<pre class="idl">[Supplemental] interface <span>Element</span> {
<span>ClientRectList</span> <span>getClientRects</span>();
<span>ClientRect</span> <span>getBoundingClientRect</span>();
// scrolling
void <span title="dom-Element-scrollIntoView">scrollIntoView</span>(optional boolean <var title="">top</var>);
attribute long <span>scrollTop</span>; // scroll on setting
attribute long <span>scrollLeft</span>; // scroll on setting
readonly attribute long <span>scrollWidth</span>;
readonly attribute long <span>scrollHeight</span>;
readonly attribute long <span>clientTop</span>;
readonly attribute long <span>clientLeft</span>;
readonly attribute long <span>clientWidth</span>;
readonly attribute long <span>clientHeight</span>;
};</pre>
<h3>The <code title="">getClientRects()</code> and
<code title="">getBoundingClientRect()</code> methods</h3>
<p>The <code>getClientRects()</code> and <code>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
<em class="ct">must</em> be static. That is, changes to the underlying
document are not reflected in the objects.</p>
<p>The
<dfn id="dom-element-getclientrects"><code>getClientRects()</code></dfn>
method, when invoked, <em class="ct">must</em> return the result of the
following algorithm:</p>
<ol>
<li><p>If the element on which it was invoked does not have an associated
CSS layout box 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.</p></li>
<li><p>If the element does not have an associated CSS layout box 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.
[<cite><span>SVG</span></cite>]</p></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.
[<cite><span>CSS21</span></cite>]</p></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.
[<cite><span>CSS21</span></cite>]</p></li>
</ul>
</li>
</ol>
<p>The
<dfn id="dom-element-getboundingclientrect"><code>getBoundingClientRect()</code></dfn>
method, when invoked, <em class="ct">must</em> return the result of the
following algorithm:</p>
<ol>
<li><p>Let <var>list</var> be the result of invoking
<code>getClientRects()</code> on the same element this method was invoked
on.</p></li>
<li><p>If the <var>list</var> is empty return a <code>ClientRect</code>
object whose <code title="dom-clientrect-top">top</code>,
<code title="dom-clientrect-right">right</code>,
<code title="dom-clientrect-bottom">bottom</code> and
<code title="dom-clientrect-left">left</code> members are zero.</p></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.</p></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>
<h3><code title="">Element</code> Scrolling Members</h3>
<p>To <dfn>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 <span>viewport</span> that establishes a
scrolling box, in order of innermost to outermost scrolling box:</p>
<ol>
<li><p>If the <code>Document</code> associated with the element to be
scrolled into view is not <span>same origin</span> with the
<code>Document</code> associated with the element or
<span>viewport</span> associated with the scrolling box, terminate these
steps.</p></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.</p></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.</p></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.</p</li>
<!-- RTL is not special cased in implementations?! -->
<li><p>If the aligning did not cause content to move terminate these
steps.</p></li>
<li>
<dl>
<dt>If the scrolling box is associated with an element</dt>
<dd><p><span>Queue a task</span> to <span>fire a simple event</span>
named <code title="event-scroll">scroll</code> at the element
associated with the scrolling box, unless a <span>task</span> to fire
that event at that element was already
<span title="queue a task">queued</span>.</p></dd>
<dt>If the scrolling box is associated with a <span>viewport</span></dt>
<dd><p><span>Queue a task</span> to <span>fire a simple event</span>
named <code title="event-scroll">scroll</code> that bubbles at the
<code>Document</code> object associated with the <span>viewport</span>,
unless a <span>task</span> to fire that event at that
<code>Document</code> object was already
<span title="queue a task">queued</span>.</p></dd>
</dl>
</li>
</ol>
<p>To <dfn>scroll an element</dfn> to <var title="">x</var>,<var title="">y</var> means to:</p>
<ol>
<li><p>If either <var title="">x</var> or <var title="">y</var> is
infinite or NaN terminate this algorithm.</p>
<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>,
<span>content</span> width -
<span>content edge</span> width)).</p></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>,
<span>content edge</span> width -
<span>content</span> width)).</p></dd>
</dl>
</li>
<li><p>Let <var title="">y</var> be max(0, min(<var title="">y</var>,
<span>content</span> height - <span>content edge</span> height)).</p></li>
<li><p>Align <span>content</span> x-coordinate <var title="">x</var> with
the left of the <span>content edge</span> of the element and align
<span>content</span> y-coordinate <var title="">y</var> with
the top of the <span>content edge</span> of the element.</p></li>
<li><p>If the aligning caused content to move <span>queue a task</span>
to <span>fire a simple event</span> named
<code title="event-scroll">scroll</code> at the element, unless a
<span>task</span> to fire that event at that element was already
<span title="queue a task">queued</span>.</p></li>
</ol>
<p>The
<dfn id="dom-element-scrollintoview" title="dom-Element-scrollIntoView"><code>scrollIntoView([<var title="">top</var>])</code></dfn>
method <em class="ct">must</em> run these steps:</p>
<ol>
<li><p>If the element does not have any associated CSS layout box
terminate these steps.</p></li>
<li><p><span title="scroll an element into view">Scroll the element into view</span>
with the <i title="">align to top flag</i> set if <var title="">top</var>
is true or omitted.</p></li>
</ol>
<p>The <dfn id="dom-element-scrolltop"><code>scrollTop</code></dfn>
attribute <em class="ct">must</em> return the result of running these
steps:</p>
<ol>
<li><p>If the element does not have any associated CSS layout box or the
element is the root element and the <code>Document</code> is in
<span>quirks mode</span> return zero and terminate these steps.</p></li>
<li><p>If the element is the root element return the value of
<code title="dom-Window-scrollY">scrollY</code>.</p></li>
<li><p>If the element is <span>the HTML <code>body</code> element</span>,
the <code>Document</code> is in <span>quirks mode</span>, and the element
does not have any overflow, return the value of
<code title="dom-Window-scrollY">scrollY</code>.</p></li>
<li><p>Return the y-coordinate of the <span>content</span> at the
alignment point with the top of the <span>content edge</span> of the
element.</p></li>
</ol>
<p>When setting the <code>scrollTop</code> attribute these steps
<em class="ct">must</em> be run:</p>
<ol>
<li><p>Let <var title="">y</var> be the given value.</p></li>
<li><p>If the element does not have any associated CSS layout box, the
element is the root element and the <code>Document</code> is in
<span>quirks mode</span>, or the element has no overflow, terminate these
steps.</p></li>
<li><p>If the element is the root element invoke
<code title="dom-Window-scroll">scroll()</code> with zero as first
argument and <var title="">y</var> as second.</p></li>
<li><p>If the element is <span>the HTML <code>body</code> element</span>,
the <code>Document</code> is in <span>quirks mode</span>, and the element
does not have any vertical overflow, invoke
<code title="dom-Window-scroll">scroll()</code> with
<code title="dom-Window-scrollX">scrollX</code> as first
argument and <var title="">y</var> as second.</p></li>
<li><p><span title="scroll an element">Scroll the element</span> to
<code>scrollLeft</code>,<var title="">y</var>.</p></li>
</ol>
<p>The <dfn id="dom-element-scrollleft"><code>scrollLeft</code></dfn>
attribute <em class="ct">must</em> return the result of running these
steps:</p>
<ol>
<li><p>If the element does not have any associated CSS layout box or the
element is the root element and the <code>Document</code> is in
<span>quirks mode</span> return zero and terminate these steps.</p></li>
<li><p>If the element is the root element return the value of
<code title="dom-Window-scrollX">scrollX</code>.</p></li>
<li><p>If the element is <span>the HTML <code>body</code> element</span>,
the <code>Document</code> is in <span>quirks mode</span>, and the element
does not have any overflow, return the value of
<code title="dom-Window-scrollX">scrollX</code>.</p></li>
<li><p>Return the x-coordinate of the <span>content</span> at the
alignment point with the left of the <span>content edge</span> of the
element.</p></li>
</ol>
<p>When setting the <code>scrollLeft</code> attribute these steps
<em class="ct">must</em> be run:</p>
<ol>
<li><p>Let <var title="">x</var> be the given value.</p></li>
<li><p>If the element does not have any associated CSS layout box, the
element is the root element and the <code>Document</code> is in
<span>quirks mode</span>, or the element has no overflow, terminate these
steps.</p></li>
<li><p>If the element is the root element invoke
<code title="dom-Window-scroll">scroll()</code> with
<var title="">x</var> as first argument and zero as second.</p></li>
<li><p>If the element is <span>the HTML <code>body</code> element</span>,
the <code>Document</code> is in <span>quirks mode</span>, and the element
does not have any vertical overflow, invoke
<code title="dom-Window-scroll">scroll()</code> with
<var title="">x</var> as first argument and
<code title="dom-Window-scrollY">scrollY</code> as second.</p></li>
<li><p><span title="scroll an element">Scroll the element</span> to
<var title="">x</var>,<code>scrollTop</code>.</p></li>
</ol>
<p>The <dfn id="dom-element-scrollwidth"><code>scrollWidth</code></dfn>
attribute <em class="ct">must</em> return the result of running these
steps:</p>
<ol>
<li><p>If the element does not have any associated CSS layout box return
zero and terminate these steps.</p></li>
<li><p>If the element is the root element and the <code>Document</code>
is not in <span>quirks mode</span> return the value of
<code>innerWidth</code>.</p></li>
<li><p>If the element is <span>the HTML <code>body</code> element</span>
and the <code>Document</code> is in <span>quirks mode</span> return the
value of <code>innerWidth</code>.</p></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 <span>content</span> width of the element.</p></li>
</ol>
<p>The <dfn id="dom-element-scrollheight"><code>scrollHeight</code></dfn>
attribute <em class="ct">must</em> return the result of running these
steps:</p>
<ol>
<li><p>If the element does not have any associated CSS layout box return
zero and terminate these steps.</p></li>
<li><p>If the element is the root element and the <code>Document</code>
is not in <span>quirks mode</span> return the value of
<code>innerHeight</code>.</p></li>
<li><p>If the element is <span>the HTML <code>body</code> element</span>
and the <code>Document</code> is in <span>quirks mode</span> return the
value of <code>innerHeight</code>.</p></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 <span>content</span> height of the element.</p></li>
</ol>
<!-- for inline boxes offsetWidth and offsetHeight are identical to offset* -->
<h3 id="client-attributes">The <code title="">clientTop</code>,
<code title="">clientLeft</code>, <code title="">clientWidth</code>, and
<code title="">clientHeight</code> attributes</h3>
<p>The <dfn id="dom-element-clienttop"><code>clientTop</code></dfn>,
<dfn id="dom-element-clientleft"><code>clientLeft</code></dfn>,
<dfn id="dom-element-clientwidth"><code>clientWidth</code></dfn>, and
<dfn id="dom-element-clientheight"><code>clientHeight</code></dfn>
attributes <em class="ct">must</em> return zero if the element does not
have any associated CSS layout box or if the CSS layout box is inline.
Otherwise, these attributes <em class="ct">must</em> behave as defined in
the remainder of this section.</p>
<p>The <code>clientTop</code> attribute returns the computed value of the
'<code>border-top-width</code>' property plus the width of any scrollbar
rendered between the top <span>padding edge</span> and the top
<span>border edge</span>.</p>
<p>The <code>clientLeft</code> attribute returns the computed
value of the '<code>border-left-width</code>' property plus the width of
any scrollbar rendered between the left <span>padding edge</span> and the
left <span>border edge</span>.
<p>The <code>clientWidth</code> attribute returns the
<span>viewport</span> width excluding the size of a rendered scroll bar
(if any) if the element is the root element and the
width of the <span>padding edge</span> (excluding the width of any
rendered scrollbar between the <span>padding edge</span> and the
<span>border edge</span>) otherwise.</p>
<p>The <code>clientHeight</code> attribute returns the
<span>viewport</span> height excluding the size of a rendered scroll bar
(if any) if the element is the root element and the
height of the <span>padding edge</span> (excluding the width of any
rendered scrollbar between the <span>padding edge</span> and the
<span>border edge</span>) otherwise.</p>
<h2 id="extensions-to-the-htmlelement-interface">Extensions to the <code title="">HTMLElement</code> Interface</h2>
<pre class="idl">[Supplemental] interface <span>HTMLElement</span> {
readonly attribute Element <span>offsetParent</span>;
readonly attribute long <span>offsetTop</span>;
readonly attribute long <span>offsetLeft</span>;
readonly attribute long <span>offsetWidth</span>;
readonly attribute long <span>offsetHeight</span>;
};</pre>
<h3 id="offset-attributes">The <code title="">offsetParent</code>,
<code title="">offsetTop</code>, <code title="">offsetLeft</code>,
<code title="">offsetWidth</code>, and <code title="">offsetHeight</code>
attributes</h3>
<p>The
<dfn id="dom-htmlelement-offsetparent"><code>offsetParent</code></dfn>
attribute <em class="ct">must</em> 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 CSS layout box.</li>
<li>The element is the root element.</li>
<li>The element is
<span>the HTML <code>body</code> element</span>.</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 <span>the HTML <code>body</code> element</span>.</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 <span title="HTML element">HTML elements</span>:
<code>td</code>, <code>th</code>, or <code>table</code>.</li>
</ul>
</li>
<li><p>Return null.</p></li>
</ol>
<p>The <dfn id="dom-htmlelement-offsettop"><code>offsetTop</code></dfn>
attribute <em class="ct">must</em> return the result of running these
steps:</p>
<ol>
<li><p>If the element is <span>the HTML <code>body</code> element</span>
or does not have any associated CSS layout box return zero and terminate
this algorithm.</p></li>
<li><p>If the <code>offsetParent</code> of the element is null return the
y-coordinate of the top <span>border edge</span> of the first