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<!DOCTYPE html>
<html lang='en'><head><meta http-equiv='content-type' content='text/html; charset=UTF-8' /></head><body>
<div class="entry-content">
<div class="entry-title roundTop">
<h1 class="jq-clearfix">.data()</h1>
<div class="entry-meta jq-clearfix">
Categories:
<span class="category"><a href="http://api.jquery.com/category/data/" title="View all posts in Data">Data</a></span> | <span class="category"><a href="http://api.jquery.com/category/miscellaneous/" title="View all posts in Miscellaneous">Miscellaneous</a> > <a href="http://api.jquery.com/category/miscellaneous/data-storage/" title="View all posts in Data Storage">Data Storage</a></span>
</div>
</div>
<div class="toc">
<h4><span>Contents:</span></h4>
<ul class="toc-list">
<li>
<a href="#data1">data( key , value ) </a><ul>
<li>.data( key, value )
</li>
<li>.data( obj )
</li>
</ul>
</li>
<li>
<a href="#data2">data( key ) </a><ul>
<li>.data( key )
</li>
<li>.data()
</li>
</ul>
</li>
</ul>
</div>
<div id="data1" class="entry method">
<h2 class="jq-clearfix roundTop section-title">
<span class="name">.data( key, value )</span> <span class="returns">Returns: <a class="return" href="http://api.jquery.com/Types/#jQuery">jQuery</a></span>
</h2>
<div class="jq-box roundBottom entry-details">
<p class="desc"><strong>Description: </strong>Store arbitrary data associated with the matched elements.</p>
<ul class="signatures">
<li class="signature" id="data-key-value">
<h4 class="name">
<span class="versionAdded">version added: <a href="/category/version/1.2.3/">1.2.3</a></span>.data( key, value )</h4>
<p class="arguement"><strong>key</strong>A string naming the piece of data to set.</p>
<p class="arguement"><strong>value</strong>The new data value; it can be any Javascript type including Array or Object.</p>
</li>
<li class="signature" id="data-obj">
<h4 class="name">
<span class="versionAdded">version added: <a href="/category/version/1.4.3/">1.4.3</a></span>.data( obj )</h4>
<p class="arguement"><strong>obj</strong>An object of key-value pairs of data to update.</p>
</li>
</ul>
<div class="longdesc">
<p>The <code>.data()</code> method allows us to attach data of any type to DOM elements in a way that is safe from circular references and therefore from memory leaks.</p>
<p> We can set several distinct values for a single element and retrieve them later:</p>
<pre>
$('body').data('foo', 52);
$('body').data('bar', { myType: 'test', count: 40 });
$('body').data('foo'); // 52
$('body').data(); // {foo: 52, bar: { myType: 'test', count: 40 }}
</pre>
<p>In jQuery 1.4.3 setting an element's data object with <code>.data(obj)</code> extends the data previously stored with that element. jQuery itself uses the <code>.data()</code> method to save information under the names 'events' and 'handle', and also reserves any data name starting with an underscore ('_') for internal use.</p>
<p>Prior to jQuery 1.4.3 (starting in jQuery 1.4) the .data() method completely replaced all data, instead of just extending the data object. If you are using third-party plugins it may not be advisable to completely replace the element's data object, since plugins may have also set data.</p>
<p>Due to the way browsers interact with plugins and external code, the <code>.data()</code> method cannot be used on <code><object></code> (unless it's a Flash plugin), <code><applet></code> or <code><embed></code> elements.</p>
</div>
<h3 id="notes-0">Additional Notes:</h3>
<div class="longdesc"><ul><li>Note that this method currently does not provide cross-platform support for setting data on XML documents, as Internet Explorer does not allow data to be attached via expando properties.</li></ul></div>
<h3>Example:</h3>
<div class="entry-examples" id="entry-examples"><div id="example-0">
<h4><span class="desc">Store then retrieve a value from the div element.</span></h4>
<pre class="prettyprint"><code class="example demo-code"><!DOCTYPE html>
<html>
<head>
<style>
div { color:blue; }
span { color:red; }
</style>
<script src="http://code.jquery.com/jquery-1.7rc2.js"></script>
</head>
<body>
<div>
The values stored were
<span></span>
and
<span></span>
</div>
<script>
$("div").data("test", { first: 16, last: "pizza!" });
$("span:first").text($("div").data("test").first);
$("span:last").text($("div").data("test").last);
</script>
</body>
</html></code></pre>
<h4>Demo:</h4>
<div class="demo code-demo"></div>
</div></div>
</div>
</div>
<div id="data2" class="entry method">
<h2 class="jq-clearfix roundTop section-title">
<span class="name">.data( key )</span> <span class="returns">Returns: <a class="return" href="http://api.jquery.com/Types/#Object">Object</a></span>
</h2>
<div class="jq-box roundBottom entry-details">
<p class="desc"><strong>Description: </strong>Returns value at named data store for the first element in the jQuery collection, as set by data(name, value).</p>
<ul class="signatures">
<li class="signature" id="data-key">
<h4 class="name">
<span class="versionAdded">version added: <a href="/category/version/1.2.3/">1.2.3</a></span>.data( key )</h4>
<p class="arguement"><strong>key</strong>Name of the data stored.</p>
</li>
<li class="signature" id="data"><h4 class="name">
<span class="versionAdded">version added: <a href="/category/version/1.4/">1.4</a></span>.data()</h4></li>
</ul>
<div class="longdesc">
<p>The <code>.data()</code> method allows us to attach data of any type to DOM elements in a way that is safe from circular references and therefore from memory leaks. We can retrieve several distinct values for a single element one at a time, or as a set:</p>
<pre>
alert($('body').data('foo'));
alert($('body').data());
</pre>
<p>The above lines alert the data values that were set on the <code>body</code> element. If no data at all was set on that element, <code>undefined</code> is returned.</p>
<pre>
alert( $("body").data("foo")); //undefined
$("body").data("bar", "foobar");
alert( $("body").data("bar")); //foobar
</pre>
<p><strong>HTML 5 data- Attributes</strong></p>
<p>As of jQuery 1.4.3 <a href="http://ejohn.org/blog/html-5-data-attributes/">HTML 5 data- attributes</a> will be automatically pulled in to jQuery's data object. The treatment of attributes with embedded dashes was changed in jQuery 1.6 to conform to the <a href="http://www.w3.org/TR/html5/elements.html#embedding-custom-non-visible-data-with-the-data-attributes">W3C HTML5 specification</a>.</p>
<p>For example, given the following HTML:</p>
<pre><div data-role="page" data-last-value="43" data-hidden="true" data-options='{"name":"John"}'></div></pre>
<p>All of the following jQuery code will work.</p>
<pre>$("div").data("role") === "page";
$("div").data("lastValue") === 43;
$("div").data("hidden") === true;
$("div").data("options").name === "John";</pre>
<p>Every attempt is made to convert the string to a JavaScript value (this includes booleans, numbers, objects, arrays, and null) otherwise it is left as a string. To retrieve the value's attribute as a string without any attempt to convert it, use the <code><a href="/attr/">attr()</a></code> method. When the data attribute is an object (starts with '{') or array (starts with '[') then <code>jQuery.parseJSON</code> is used to parse the string; it must follow <a href="http://en.wikipedia.org/wiki/JSON#Data_types.2C_syntax_and_example">valid JSON syntax</a> <em>including quoted property names</em>. The data- attributes are pulled in the first time the data property is accessed and then are no longer accessed or mutated (all data values are then stored internally in jQuery).</p>
<p>Calling <code>.data()</code> with no parameters retrieves all of the values as a JavaScript object. This object can be safely cached in a variable as long as a new object is not set with <code>.data(obj)</code>. Using the object directly to get or set values is faster than making individual calls to <code>.data()</code> to get or set each value:</p>
<pre>
var mydata = $("#mydiv").data();
if ( mydata.count < 9 ) {
mydata.count = 43;
mydata.status = "embiggened";
}
</pre>
</div>
<h3 id="notes-1">Additional Notes:</h3>
<div class="longdesc"><ul><li>Note that this method currently does not provide cross-platform support for setting data on XML documents, as Internet Explorer does not allow data to be attached via expando properties.</li></ul></div>
<h3>Example:</h3>
<div class="entry-examples" id="entry-examples-1"><div id="example-1-0">
<h4><span class="desc">Get the data named "blah" stored at for an element.</span></h4>
<pre class="prettyprint"><code class="example demo-code"><!DOCTYPE html>
<html>
<head>
<style>
div { margin:5px; background:yellow; }
button { margin:5px; font-size:14px; }
p { margin:5px; color:blue; }
span { color:red; }
</style>
<script src="http://code.jquery.com/jquery-1.7rc2.js"></script>
</head>
<body>
<div>A div</div>
<button>Get "blah" from the div</button>
<button>Set "blah" to "hello"</button>
<button>Set "blah" to 86</button>
<button>Remove "blah" from the div</button>
<p>The "blah" value of this div is <span>?</span></p>
<script>
$("button").click(function(e) {
var value;
switch ($("button").index(this)) {
case 0 :
value = $("div").data("blah");
break;
case 1 :
$("div").data("blah", "hello");
value = "Stored!";
break;
case 2 :
$("div").data("blah", 86);
value = "Stored!";
break;
case 3 :
$("div").removeData("blah");
value = "Removed!";
break;
}
$("span").text("" + value);
});
</script>
</body>
</html></code></pre>
<h4>Demo:</h4>
<div class="demo code-demo"></div>
</div></div>
</div>
</div>
</div>
</body></html>
|
