264 lines
17 KiB
HTML
264 lines
17 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
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<html>
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<head>
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<title>YUI Library Examples: YAHOO Global Object: Creating Class Hierarchies with <code>YAHOO.lang.extend</code></title>
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<meta http-equiv="content-type" content="text/html; charset=utf-8">
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<link rel="stylesheet" type="text/css" href="../../assets/yui.css" >
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<style>
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/*Supplemental CSS for the YUI distribution*/
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#custom-doc { width: 95%; min-width: 950px; }
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#pagetitle {background-image: url(../../assets/bg_hd.gif);}
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#pagetitle h1 {background-image: url(../../assets/title_h_bg.gif);}
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</style>
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<link rel="stylesheet" type="text/css" href="../../assets/dpSyntaxHighlighter.css">
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<!--Script and CSS includes for YUI dependencies on this page-->
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<link rel="stylesheet" type="text/css" href="../../build/button/assets/skins/sam/button.css" />
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<script type="text/javascript" src="../../build/yahoo/yahoo-min.js"></script>
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<script type="text/javascript" src="../../build/dom/dom-min.js"></script>
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<script type="text/javascript" src="../../build/event/event-min.js"></script>
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<script type="text/javascript" src="../../build/element/element-beta-min.js"></script>
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<script type="text/javascript" src="../../build/button/button-min.js"></script>
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<!--begin custom header content for this example-->
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<!--end custom header content for this example-->
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</head>
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<body id="yahoo-com" class=" yui-skin-sam">
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<div id="custom-doc" class="yui-t2">
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<div id="hd">
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<div id="ygunav">
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<p><em>
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<a href="http://developer.yahoo.com">Yahoo! Developer Network Home</a> <i> - </i>
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<a href="http://help.yahoo.com/help/us/ysearch">Help</a>
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</em>
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</p>
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<form action="http://search.yahoo.com/search"><label for="ygsp">YDN Site Search</label>
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<input name="vs" type="hidden" value="developer.yahoo.com">
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<input name="fr" type="hidden" value="ush-myweb">
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<input id="ygsp" name="va" size="22">
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<input type="submit" value="Search" class="ygbt"></form>
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</div>
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<div id="ygma"><a href="../../"><img src="../../assets/yui.gif" border="0" width="378" height="28"></a></div>
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<div id="pagetitle"><h1>YUI Library Examples: YAHOO Global Object: Creating Class Hierarchies with <code>YAHOO.lang.extend</code></h1></div>
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</div>
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<div id="bd">
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<div id="yui-main">
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<div class="yui-b">
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<div class="yui-ge">
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<div class="yui-u first example">
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<div class="promo">
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<h1>YAHOO Global Object: Creating Class Hierarchies with <code>YAHOO.lang.extend</code></h1>
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<div class="exampleIntro">
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<p>JavaScript supports the notion of class hierarchies. As in other object-oriented languages, you can create generic classes, then create specialized subclasses that add or override functionality of the superclass.</p>
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<p>Click the "Show Inheritance" button to do some evaluation of the created object.</p>
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</div>
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<div class="example-container module ">
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<div id="example-canvas" class="bd">
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<!--BEGIN SOURCE CODE FOR EXAMPLE =============================== -->
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<pre style="margin-bottom: 1em">
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var chicken = new YAHOO.example.Chicken();
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</pre>
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<input type="button" name="demo_btn" id="demo_btn" value="Show Inheritance"/>
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<div id="demo">
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</div>
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<script type="text/javascript">
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YAHOO.namespace('example');
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var Ye = YAHOO.example;
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Ye.Bird = function (name) {
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this.name = name;
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};
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Ye.Bird.prototype.flighted = true; // Default for all Birds
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Ye.Bird.prototype.isFlighted = function () { return this.flighted };
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Ye.Bird.prototype.getName = function () { return this.name };
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Ye.Chicken = function (name) {
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// Chain the constructors
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this.constructor.superclass.constructor.call(this, name);
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};
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// Chickens are birds
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YAHOO.lang.extend(Ye.Chicken, Ye.Bird);
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// Define the Chicken prototype methods/members
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Ye.Chicken.prototype.flighted = false; // Override default for all Chickens
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Ye.showInheritance = function () {
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var chicken = new Ye.Chicken('Little'),
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results = YAHOO.util.Dom.get('demo');
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results.innerHTML = chicken instanceof Object ?
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"<p>chicken IS an instance of Object.</p>" :
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"<p>chicken IS NOT an instance of Object.</p>";
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results.innerHTML += chicken instanceof Ye.Bird ?
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"<p>chicken IS an instance of YAHOO.example.Bird.</p>" :
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"<p>chicken IS NOT an instance of YAHOO.example.Bird.</p>";
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results.innerHTML += chicken instanceof Ye.Chicken ?
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"<p>chicken IS an instance of YAHOO.example.Chicken.</p>" :
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"<p>chicken IS NOT an instance of YAHOO.example.Chicken.</p>";
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// Chicken instances inherit Bird methods and members
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results.innerHTML += chicken.isFlighted() ?
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"<p>chicken CAN fly.</p>" :
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"<p>chicken CAN NOT fly.</p>";
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results.innerHTML += "<p>chicken's name is " + chicken.getName() + ".</p>";
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}
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YAHOO.util.Event.on('demo_btn','click', Ye.showInheritance);
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</script>
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<!--END SOURCE CODE FOR EXAMPLE =============================== -->
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</div>
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</div>
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</div>
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<h2 class="first">YAHOO.lang is packaged with the YAHOO Global Object</h2>
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<p><code>YAHOO.lang</code> comes bundled with the <a href="http://developer.yahoo.com/yui/yahoo/">YAHOO Global Object</a>. To add the YAHOO Global Object, include the following in your markup:</p>
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<textarea name="code" class="HTML" cols="60" rows="1">
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<script type="text/javascript" src="http://yui.yahooapis.com/2.3.1/build/yahoo/yahoo-min.js"></script>
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</textarea>
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<p>If you are using any other YUI component on your page, you should already have <code>YAHOO.lang</code> available.</p>
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<h2>Creating a class hierarchy</h2>
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<p>In this example, we create a class <code>YAHOO.example.Bird</code> then create a subclass <code>YAHOO.example.Chicken</code>.
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<textarea name="code" class="JScript" cols="60" rows="1">
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var Ye = YAHOO.example;
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Ye.Bird = function (name) {
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this.name = name;
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};
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Ye.Bird.prototype.flighted = true; // Default for all Birds
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Ye.Bird.prototype.isFlighted = function () { return this.flighted };
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Ye.Bird.prototype.getName = function () { return this.name };
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Ye.Chicken = function (name) {
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// Chain the constructors
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this.constructor.superclass.constructor.call(this, name);
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};
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// Chickens are Birds
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YAHOO.lang.extend(Ye.Chicken, Ye.Bird);
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// Define the Chicken prototype methods/members
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Ye.Chicken.prototype.flighted = false; // Override default for all Chickens
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</textarea>
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<h2><code>instanceof</code> many classes</h2>
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<p>Unlike classes composed with augmentation, extending subclasses are also considered instances of their superclass and all classes higher up the inheritance tree.</p>
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<p>We'll create an instance of <code>YAHOO.example.Chicken</code> and run some <code>instanceof</code> and method tests against it.</p>
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<textarea name="code" class="JScript" cols="60" rows="1">
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YAHOO.util.Event.on('demo_btn','click', function () {
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// Create a test Chicken
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var chicken = new Ye.Chicken('Little');
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var results = YAHOO.util.Dom.get('demo');
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// Is the chicken an instanceof Object?
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results.innerHTML = chicken instanceof Object ?
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"<p>chicken IS an instance of Object.</p>" :
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"<p>chicken IS NOT an instance of Object.</p>";
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// Is the chicken an instanceof YAHOO.example.Bird?
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results.innerHTML += chicken instanceof Ye.Bird ?
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"<p>chicken IS an instance of YAHOO.example.Bird.</p>" :
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"<p>chicken IS NOT an instance of YAHOO.example.Bird.</p>";
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// Is the chicken an instanceof YAHOO.example.Chicken?
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results.innerHTML += chicken instanceof Ye.Chicken ?
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"<p>chicken IS an instance of YAHOO.example.Chicken.</p>" :
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"<p>chicken IS NOT an instance of YAHOO.example.Chicken.</p>";
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// instances inherit methods and members from their superclass and ancestors
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results.innerHTML += chicken.isFlighted() ?
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"<p>chicken CAN fly.</p>" :
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"<p>chicken CAN NOT fly.</p>";
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results.innerHTML += "<p>chicken's name is " + chicken.getName() + ".</p>";
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});
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</textarea>
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<h2>Other architecture strategies</h2>
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<p>Take a look at <code>YAHOO.lang.augmentProto</code> and <code>YAHOO.lang.augmentObject</code> for different strategies of managing your code structure.
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</div>
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<div class="yui-u">
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<div id="examples">
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<h3 class='firstContent'>YAHOO Global Object Examples:</h3>
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<div id="exampleToc">
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<ul>
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<li><a href='../yahoo/yahoo_type_checking.html'>Type-Checking Your Data</a></li><li><a href='../yahoo/yahoo_ua_detection.html'>User Agent Detection</a></li><li class='selected'><a href='../yahoo/yahoo_extend.html'>Creating Class Hierarchies with <code>YAHOO.lang.extend</code></a></li><li><a href='../yahoo/yahoo_augment_proto.html'>Creating a Composition-Based Class Structure Using <code>YAHOO.lang.augmentProto</code></a></li><li><a href='../yahoo/yahoo_augment_object.html'>Add Behavior to Objects or Static Classes with <code>YAHOO.lang.augmentObject</code></a></li><li><a href='../yahoo/yahoo_merge.html'>Combining Simple Data Sets with <code>YAHOO.lang.merge</code></a></li> </ul>
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</div>
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</div>
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<div id="module">
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<h3>More YAHOO Global Object Resources:</h3>
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<ul>
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<li><a href="http://developer.yahoo.com/yui/yahoo/">User's Guide</a> (external)</li>
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<li><a href="../../docs/module_yahoo.html">API Documentation</a></li>
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</ul>
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</div>
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</div>
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</div>
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</div>
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</div>
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<div class="yui-b" id="tocWrapper">
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<!-- TABLE OF CONTENTS -->
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<div id="toc">
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<ul>
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<li class="sect first">Yahoo! UI Library</li><li class="item"><a title="The Yahoo! User Interface Library (YUI)" href="http://developer.yahoo.com/yui/">Home (external)</a></li><li class="item"><a title="The Yahoo! User Interface Blog" href="http://yuiblog.com">YUIBlog (external)</a></li><li class="item"><a title="The Yahoo! Group YDN-JavaScript hosts the YUI community forum" href="http://tech.groups.yahoo.com/group/ydn-javascript/">YUI Discussion Forum (external)</a></li><li class="item"><a title="The YUI Library can be downloaded from SourceForge" href="http://sourceforge.net/projects/yui/">YUI on Sourceforge (external)</a></li><li class="item"><a title="Instantly searchable API documentation for the entire YUI library." href="../../docs/index.html">API Documentation</a></li><li class="item"><a title="Examples of every YUI utility and control in action" href="../../examples/">Functional Examples</a></li><li class="item"><a title="Videos and podcasts from the YUI Team and from the Yahoo! frontend engineering community." href="http://developer.yahoo.com/yui/theater/">YUI Theater (external)</a></li><li class="item"><a title="YUI is free and open, offered under a BSD license." href="http://developer.yahoo.com/yui/license.html">YUI License (external)</a></li><li class="sect">YUI Functional Examples</li><li class="item"><a title="The YUI Animation Utility - Functional Examples" href="../../examples/animation/index.html">Animation</a></li><li class="item"><a title="The YUI AutoComplete Control - Functional Examples" href="../../examples/autocomplete/index.html">AutoComplete</a></li><li class="item"><a title="The YUI Browser History Manager - Functional Examples" href="../../examples/history/index.html">Browser History Manager</a></li><li class="item"><a title="The YUI Button Control - Functional Examples" href="../../examples/button/index.html">Button</a></li><li class="item"><a title="The YUI Calendar Control - Functional Examples" href="../../examples/calendar/index.html">Calendar</a></li><li class="item"><a title="The YUI Charts Control - Functional Examples" href="../../examples/charts/index.html">Charts (experimental)</a></li><li class="item"><a title="The YUI Color Picker Control - Functional Examples" href="../../examples/colorpicker/index.html">Color Picker</a></li><li class="item"><a title="The YUI Cookie Utility - Functional Examples" href="../../examples/cookie/index.html">Cookie (beta)</a></li><li class="item"><a title="The YUI Connection Manager (AJAX) - Functional Examples" href="../../examples/connection/index.html">Connection Manager</a></li><li class="item"><a title="The YUI Container Family (Module, Overlay, Tooltip, Panel, Dialog, SimpleDialog) - Functional Examples" href="../../examples/container/index.html">Container</a></li><li class="item"><a title="The YUI DataTable Control - Functional Examples" href="../../examples/datatable/index.html">DataTable (beta)</a></li><li class="item"><a title="The YUI Dom Collection - Functional Examples" href="../../examples/dom/index.html">Dom</a></li><li class="item"><a title="The YUI Drag & Drop Utility - Functional Examples" href="../../examples/dragdrop/index.html">Drag & Drop</a></li><li class="item"><a title="The YUI Event Utility - Functional Examples" href="../../examples/event/index.html">Event</a></li><li class="item"><a title="The YUI Get Utility - Functional Examples" href="../../examples/get/index.html">Get</a></li><li class="item"><a title="The YUI ImageCropper Control - Functional Examples" href="../../examples/imagecropper/index.html">ImageCropper (beta)</a></li><li class="item"><a title="The YUI ImageLoader Utility - Functional Examples" href="../../examples/imageloader/index.html">ImageLoader</a></li><li class="item"><a title="The YUI JSON Utility - Functional Examples" href="../../examples/json/index.html">JSON</a></li><li class="item"><a title="The YUI Layout Manager - Functional Examples" href="../../examples/layout/index.html">Layout Manager (beta)</a></li><li class="item"><a title="The YUI Logger Control - Functional Examples" href="../../examples/logger/index.html">Logger</a></li><li class="item"><a title="The YUI Menu Control - Functional Examples" href="../../examples/menu/index.html">Menu</a></li><li class="item"><a title="The YUI Profiler Utility - Functional Examples" href="../../examples/profiler/index.html">Profiler (beta)</a></li><li class="item"><a title="The YUI ProfileViewer Control - Functional Examples" href="../../examples/profilerviewer/index.html">ProfilerViewer (beta)</a></li><li class="item"><a title="The YUI Resize Utility - Functional Examples" href="../../examples/resize/index.html">Resize (beta)</a></li><li class="item"><a title="The YUI Rich Text Editor - Functional Examples" href="../../examples/editor/index.html">Rich Text Editor (beta)</a></li><li class="item"><a title="The YUI Selector Utility - Functional Examples" href="../../examples/selector/index.html">Selector (beta)</a></li><li class="item"><a title="The YUI Slider Control - Functional Examples" href="../../examples/slider/index.html">Slider</a></li><li class="item"><a title="The YUI TabView Control - Functional Examples" href="../../examples/tabview/index.html">TabView</a></li><li class="item"><a title="The YUI TreeView Control - Functional Examples" href="../../examples/treeview/index.html">TreeView</a></li><li class="item"><a title="The YUI Uploader Utility - Functional Examples" href="../../examples/uploader/index.html">Uploader (experimental)</a></li><li class="selected "><a title="The YUI YAHOO Global Object - Functional Examples" href="../../examples/yahoo/index.html">YAHOO Global Object</a></li><li class="item"><a title="The YUI Loader Utility - Functional Examples" href="../../examples/yuiloader/index.html">YUI Loader (beta)</a></li><li class="item"><a title="The YUI Test Utility - Functional Examples" href="../../examples/yuitest/index.html">YUI Test</a></li><li class="item"><a title="YUI Reset CSS - Functional Examples" href="../../examples/reset/index.html">Reset CSS</a></li><li class="item"><a title="YUI Base CSS - Functional Examples" href="../../examples/base/index.html">Base CSS</a></li><li class="item"><a title="YUI Fonts CSS - Functional Examples" href="../../examples/fonts/index.html">Fonts CSS</a></li><li class="item"><a title="YUI Grids CSS - Functional Examples" href="../../examples/grids/index.html">Grids CSS</a></li><li class="sect">YUI Articles on the YUI Website</li><li class="item"><a title="Answers to Frequently Asked Questions about the YUI Library" href="http://developer.yahoo.com/yui/articles/faq/">YUI FAQ (external)</a></li><li class="item"><a title="Yahoo!'s philosophy of Graded Browser Support" href="http://developer.yahoo.com/yui/articles/gbs/">Graded Browser Support (external)</a></li><li class="item"><a title="Reporting Bugs and Making Feature Requests for YUI Components" href="http://developer.yahoo.com/yui/articles/reportingbugs/">Bug Reports/Feature Requests (external)</a></li><li class="item"><a title="Serve YUI source files from Yahoo! -- free, fast, and simple" href="http://developer.yahoo.com/yui/articles/hosting/">Serving YUI Files from Yahoo! (external)</a></li><li class="item"><a title="Best practices for working with web services while protecting user privacy" href="http://developer.yahoo.com/security/">Security Best Practices (external)</a></li></ul>
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</div>
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</div>
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</div><!--closes bd-->
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<div id="ft">
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<p class="first">Copyright © 2008 Yahoo! Inc. All rights reserved.</p>
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<p><a href="http://privacy.yahoo.com/privacy/us/devel/index.html">Privacy Policy</a> -
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<a href="http://docs.yahoo.com/info/terms/">Terms of Service</a> -
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<a href="http://docs.yahoo.com/info/copyright/copyright.html">Copyright Policy</a> -
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<a href="http://careers.yahoo.com/">Job Openings</a></p>
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</div>
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</div>
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<script src="../../assets/dpSyntaxHighlighter.js"></script>
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<script language="javascript">
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dp.SyntaxHighlighter.HighlightAll('code');
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