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247 lines
25 KiB
HTML
247 lines
25 KiB
HTML
<article class="" id="post-">
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<header class="entry-header">
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<h1 class="entry-title">.each()</h1>
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<div class="entry-meta">
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所属分类：<span class="category"><a href="/category/miscellaneous/">杂项</a> > <a href="/category/miscellaneous/collection-manipulation/">集合操作</a></span><span class="category-divider"> | </span><span class="category"><a href="/category/traversing/">遍历</a></span>
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<span class="pull-right">英文文档：<a href="https://api.jquery123.com/each/" target="_blank">.each()</a></span>
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</div><!-- .entry-meta -->
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</header><!-- .entry-header -->
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<!-- .entry-header -->
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<div class="entry-content">
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<article class="entry method" id="each1"><h2 class="section-title">
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<span class="name">.each( function(index, Element) )</span><span class="returns">返回: <a href="/Types/#jQuery">jQuery</a></span>
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</h2>
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<div class="entry-wrapper">
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<p class="desc"><strong>描述: </strong>遍历一个jQuery对象，为每个匹配元素执行一个函数。</p>
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<ul class="signatures"><li class="signature" id="each-functionindex--Element">
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<h4 class="name">
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<span class="version-details">添加的版本: <a href="/category/version/1.0/">1.0</a></span>.each( function(index, Element) )</h4>
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<ul><li>
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<div><strong>function(index, Element)</strong></div>
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<div>类型: <a href="/Types/#Function">Function</a>()</div>
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<div>
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为每个匹配元素执行的一个函数。</div>
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</li></ul>
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</li></ul>
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<div class="longdesc" id="entry-longdesc">
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<p><code>.each()</code> 方法用来让DOM循环结构更简单更不易出错。它会迭代jQuery对象中的每一个DOM元素。每次回调函数执行时，会传递当前循环次数作为参数(从0开始计数)。更重要的是，回调函数是在当前DOM元素为上下文的语境中触发的。因此关键字 <code>this</code> 总是指向这个元素。</p>
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<p>假设页面上有这样一个简单的无序列表。</p>
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<div class="syntaxhighlighter xml nogutter">
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<div class="line n1">1</div>
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<td class="code">
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<pre><div class="container"><div class="line"><code><span class="tag"><<span class="title">ul</span>></span></code></div></div><div class="container"><div class="line"><code> <span class="tag"><<span class="title">li</span>></span>foo<span class="tag"></<span class="title">li</span>></span></code></div></div><div class="container"><div class="line"><code> <span class="tag"><<span class="title">li</span>></span>bar<span class="tag"></<span class="title">li</span>></span></code></div></div><div class="container"><div class="line"><code><span class="tag"></<span class="title">ul</span>></span></code></div></div></pre>
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</td>
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</tr>
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</tbody>
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</div>
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<p>你可以选中并迭代这些列表：</p>
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<pre><div class="container"><div class="line"><code>$( "li" ).each(function( index ) {</code></div></div><div class="container"><div class="line"><code> console.log( index + ": "" + $(this).text() );</code></div></div><div class="container"><div class="line"><code>});</code></div></div></pre>
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</td>
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</table>
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</div>
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<p>
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列表中每一项会显示在下面的消息中：</p>
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<p>
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<span class="output">0: foo</span>
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<br/>
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<span class="output">1: bar</span>
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</p>
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<p>我们可以通过返回 <code>false</code>以便在回调函数内中止循环。</p>
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<p>注意: jQuery的方法，返回一个jQuery对象遍历jQuery集合中的元素 - 被称为隐式<i>迭代</i>的过程。当这种情况发生时，它通常不需要显式地循环的<code>.each()</code>方法：</p>
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<div class="syntaxhighlighter javascript nogutter">
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<td class="code">
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<pre><div class="container"><div class="line"><code><span class="comment">// The .each() method is unnecessary here:</span></code></div></div><div class="container"><div class="line"><code>$( <span class="string">"li"</span> ).each(<span class="keyword">function</span>() {</code></div></div><div class="container"><div class="line"><code> $(<span class="keyword">this</span>).addClass( <span class="string">"foo"</span> );</code></div></div><div class="container"><div class="line"><code>});</code></div></div><div class="container"><div class="line"><code> </code></div></div><div class="container"><div class="line"><code><span class="comment">// Instead, you should rely on implicit iteration:</span></code></div></div><div class="container"><div class="line"><code>$( <span class="string">"li"</span> ).addClass( <span class="string">"bar"</span> );</code></div></div></pre>
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</tbody>
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</table>
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</div>
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</div>
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<section class="entry-examples" id="entry-examples"><header><h2 class="underline">例子:</h2></header><div class="entry-example" id="example-0">
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<h4>Example: <span class="desc">遍历三个div并设置它们的color属性。</span>
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</h4>
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<td class="code">
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<pre><div class="container"><div class="line"><code><span class="doctype"><!DOCTYPE html></span></code></div></div><div class="container"><div class="line"><code><span class="tag"><<span class="title">html</span>></span></code></div></div><div class="container"><div class="line"><code><span class="tag"><<span class="title">head</span>></span></code></div></div><div class="container"><div class="line"><code> <span class="tag"><<span class="title">style</span>></span><span class="css"></span></code></div></div><div class="container"><div class="line"><code> <span class="tag">div</span> <span class="rules">{ <span class="rule"><span class="attribute">color</span>:<span class="value">red;</span></span> <span class="rule"><span class="attribute">text-align</span>:<span class="value">center;</span></span> <span class="rule"><span class="attribute">cursor</span>:<span class="value">pointer;</span></span></span></code></div></div><div class="container"><div class="line"><code> <span class="rule"><span class="attribute">font-weight</span>:<span class="value">bolder;</span></span> <span class="rule"><span class="attribute">width</span>:<span class="value"><span class="number">300</span>px;</span></span> <span class="rule">}</span></code></div></div><div class="container"><div class="line"><code> <span class="tag"></<span class="title">style</span>></span></code></div></div><div class="container"><div class="line"><code> <span class="tag"><<span class="title">script</span> <span class="attribute">src</span>=<span class="value">"https://code.jquery.com/jquery-latest.js"</span>></span><span class="javascript"></span><span class="tag"></<span class="title">script</span>></span></code></div></div><div class="container"><div class="line"><code><span class="tag"></<span class="title">head</span>></span></code></div></div><div class="container"><div class="line"><code><span class="tag"><<span class="title">body</span>></span></code></div></div><div class="container"><div class="line"><code> <span class="tag"><<span class="title">div</span>></span>Click here<span class="tag"></<span class="title">div</span>></span></code></div></div><div class="container"><div class="line"><code> <span class="tag"><<span class="title">div</span>></span>to iterate through<span class="tag"></<span class="title">div</span>></span></code></div></div><div class="container"><div class="line"><code> <span class="tag"><<span class="title">div</span>></span>these divs.<span class="tag"></<span class="title">div</span>></span></code></div></div><div class="container"><div class="line"><code><span class="tag"><<span class="title">script</span>></span><span class="javascript"></span></code></div></div><div class="container"><div class="line"><code> $(document.body).click(<span class="function"><span class="keyword">function</span> <span class="params">()</span> {</span></code></div></div><div class="container"><div class="line"><code> $( <span class="string">"div"</span> ).each(<span class="function"><span class="keyword">function</span> <span class="params">(i)</span> {</span></code></div></div><div class="container"><div class="line"><code> <span class="keyword">if</span> ( <span class="keyword">this</span>.style.color != <span class="string">"blue"</span> ) {</code></div></div><div class="container"><div class="line"><code> <span class="keyword">this</span>.style.color = <span class="string">"blue"</span>;</code></div></div><div class="container"><div class="line"><code> } <span class="keyword">else</span> {</code></div></div><div class="container"><div class="line"><code> <span class="keyword">this</span>.style.color = <span class="string">""</span>;</code></div></div><div class="container"><div class="line"><code> }</code></div></div><div class="container"><div class="line"><code> });</code></div></div><div class="container"><div class="line"><code> });</code></div></div><div class="container"><div class="line"><code><span class="tag"></<span class="title">script</span>></span></code></div></div><div class="container"><div class="line"><code> </code></div></div><div class="container"><div class="line"><code><span class="tag"></<span class="title">body</span>></span></code></div></div><div class="container"><div class="line"><code><span class="tag"></<span class="title">html</span>></span></code></div></div></pre>
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</td>
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</table>
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</div>
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<h4>Demo:</h4>
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<div class="demo code-demo"></div>
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</div>
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<div class="entry-example" id="example-1">
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<h4>Example: <span class="desc">
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如果你不想要普通的DOM元素，而想获得的是jQuery对象的话，使用<code>$(this)</code>函数。例如：</span>
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</h4>
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<pre><div class="container"><div class="line"><code><span class="doctype"><!DOCTYPE html></span></code></div></div><div class="container"><div class="line"><code><span class="tag"><<span class="title">html</span>></span></code></div></div><div class="container"><div class="line"><code><span class="tag"><<span class="title">head</span>></span></code></div></div><div class="container"><div class="line"><code> <span class="tag"><<span class="title">style</span>></span><span class="css"></span></code></div></div><div class="container"><div class="line"><code> <span class="tag">ul</span> <span class="rules">{ <span class="rule"><span class="attribute">font-size</span>:<span class="value"><span class="number">18</span>px;</span></span> <span class="rule"><span class="attribute">margin</span>:<span class="value"><span class="number">0</span>;</span></span> <span class="rule">}</span></span></code></div></div><div class="container"><div class="line"><code> <span class="tag">span</span> <span class="rules">{ <span class="rule"><span class="attribute">color</span>:<span class="value">blue;</span></span> <span class="rule"><span class="attribute">text-decoration</span>:<span class="value">underline;</span></span> <span class="rule"><span class="attribute">cursor</span>:<span class="value">pointer;</span></span> <span class="rule">}</span></span></code></div></div><div class="container"><div class="line"><code> <span class="class">.example</span> <span class="rules">{ <span class="rule"><span class="attribute">font-style</span>:<span class="value">italic;</span></span> <span class="rule">}</span></span></code></div></div><div class="container"><div class="line"><code> <span class="tag"></<span class="title">style</span>></span></code></div></div><div class="container"><div class="line"><code> <span class="tag"><<span class="title">script</span> <span class="attribute">src</span>=<span class="value">"https://code.jquery.com/jquery-latest.js"</span>></span><span class="javascript"></span><span class="tag"></<span class="title">script</span>></span></code></div></div><div class="container"><div class="line"><code><span class="tag"></<span class="title">head</span>></span></code></div></div><div class="container"><div class="line"><code><span class="tag"><<span class="title">body</span>></span></code></div></div><div class="container"><div class="line"><code> To do list: <span class="tag"><<span class="title">span</span>></span>(click here to change)<span class="tag"></<span class="title">span</span>></span></code></div></div><div class="container"><div class="line"><code> <span class="tag"><<span class="title">ul</span>></span></code></div></div><div class="container"><div class="line"><code> <span class="tag"><<span class="title">li</span>></span>Eat<span class="tag"></<span class="title">li</span>></span></code></div></div><div class="container"><div class="line"><code> <span class="tag"><<span class="title">li</span>></span>Sleep<span class="tag"></<span class="title">li</span>></span></code></div></div><div class="container"><div class="line"><code> </code></div></div><div class="container"><div class="line"><code> <span class="tag"><<span class="title">li</span>></span>Be merry<span class="tag"></<span class="title">li</span>></span></code></div></div><div class="container"><div class="line"><code> <span class="tag"></<span class="title">ul</span>></span></code></div></div><div class="container"><div class="line"><code><span class="tag"><<span class="title">script</span>></span><span class="javascript"></span></code></div></div><div class="container"><div class="line"><code> $( <span class="string">"span"</span> ).click(<span class="function"><span class="keyword">function</span> <span class="params">()</span> {</span></code></div></div><div class="container"><div class="line"><code> $( <span class="string">"li"</span> ).each(<span class="keyword">function</span>(){</code></div></div><div class="container"><div class="line"><code> $( <span class="keyword">this</span> ).toggleClass( <span class="string">"example"</span> );</code></div></div><div class="container"><div class="line"><code> });</code></div></div><div class="container"><div class="line"><code> });</code></div></div><div class="container"><div class="line"><code> </code></div></div><div class="container"><div class="line"><code><span class="tag"></<span class="title">script</span>></span></code></div></div><div class="container"><div class="line"><code> </code></div></div><div class="container"><div class="line"><code><span class="tag"></<span class="title">body</span>></span></code></div></div><div class="container"><div class="line"><code><span class="tag"></<span class="title">html</span>></span></code></div></div></pre>
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</div>
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<h4>Demo:</h4>
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<div class="demo code-demo"></div>
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</div>
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<div class="entry-example" id="example-2">
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<h4>Example: <span class="desc">你可以使用 'return' 来提前结束 each() 循环。</span>
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<td class="code">
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<pre><div class="container"><div class="line"><code><span class="doctype"><!DOCTYPE html></span></code></div></div><div class="container"><div class="line"><code><span class="tag"><<span class="title">html</span>></span></code></div></div><div class="container"><div class="line"><code><span class="tag"><<span class="title">head</span>></span></code></div></div><div class="container"><div class="line"><code> <span class="tag"><<span class="title">style</span>></span><span class="css"></span></code></div></div><div class="container"><div class="line"><code> <span class="tag">div</span> <span class="rules">{ <span class="rule"><span class="attribute">width</span>:<span class="value"><span class="number">40</span>px;</span></span> <span class="rule"><span class="attribute">height</span>:<span class="value"><span class="number">40</span>px;</span></span> <span class="rule"><span class="attribute">margin</span>:<span class="value"><span class="number">5</span>px;</span></span> <span class="rule"><span class="attribute">float</span>:<span class="value">left;</span></span></span></code></div></div><div class="container"><div class="line"><code> <span class="rule"><span class="attribute">border</span>:<span class="value"><span class="number">2</span>px blue solid;</span></span> <span class="rule"><span class="attribute">text-align</span>:<span class="value">center;</span></span> <span class="rule">}</span></code></div></div><div class="container"><div class="line"><code> <span class="tag">span</span> <span class="rules">{ <span class="rule"><span class="attribute">color</span>:<span class="value">red;</span></span> <span class="rule">}</span></span></code></div></div><div class="container"><div class="line"><code> <span class="tag"></<span class="title">style</span>></span></code></div></div><div class="container"><div class="line"><code> <span class="tag"><<span class="title">script</span> <span class="attribute">src</span>=<span class="value">"https://code.jquery.com/jquery-latest.js"</span>></span><span class="javascript"></span><span class="tag"></<span class="title">script</span>></span></code></div></div><div class="container"><div class="line"><code><span class="tag"></<span class="title">head</span>></span></code></div></div><div class="container"><div class="line"><code><span class="tag"><<span class="title">body</span>></span></code></div></div><div class="container"><div class="line"><code> <span class="tag"><<span class="title">button</span>></span>Change colors<span class="tag"></<span class="title">button</span>></span></code></div></div><div class="container"><div class="line"><code> <span class="tag"><<span class="title">span</span>></span><span class="tag"></<span class="title">span</span>></span></code></div></div><div class="container"><div class="line"><code> <span class="tag"><<span class="title">div</span>></span><span class="tag"></<span class="title">div</span>></span></code></div></div><div class="container"><div class="line"><code> <span class="tag"><<span class="title">div</span>></span><span class="tag"></<span class="title">div</span>></span></code></div></div><div class="container"><div class="line"><code> </code></div></div><div class="container"><div class="line"><code> <span class="tag"><<span class="title">div</span>></span><span class="tag"></<span class="title">div</span>></span></code></div></div><div class="container"><div class="line"><code> <span class="tag"><<span class="title">div</span>></span><span class="tag"></<span class="title">div</span>></span></code></div></div><div class="container"><div class="line"><code> <span class="tag"><<span class="title">div</span> <span class="attribute">id</span>=<span class="value">"stop"</span>></span>Stop here<span class="tag"></<span class="title">div</span>></span></code></div></div><div class="container"><div class="line"><code> <span class="tag"><<span class="title">div</span>></span><span class="tag"></<span class="title">div</span>></span></code></div></div><div class="container"><div class="line"><code> </code></div></div><div class="container"><div class="line"><code> <span class="tag"><<span class="title">div</span>></span><span class="tag"></<span class="title">div</span>></span></code></div></div><div class="container"><div class="line"><code> <span class="tag"><<span class="title">div</span>></span><span class="tag"></<span class="title">div</span>></span></code></div></div><div class="container"><div class="line"><code><span class="tag"><<span class="title">script</span>></span><span class="javascript"></span></code></div></div><div class="container"><div class="line"><code> $( <span class="string">"button"</span> ).click(<span class="function"><span class="keyword">function</span> <span class="params">()</span> {</span></code></div></div><div class="container"><div class="line"><code> $( <span class="string">"div"</span> ).each(<span class="function"><span class="keyword">function</span> <span class="params">( index, domEle)</span> {</span></code></div></div><div class="container"><div class="line"><code> <span class="comment">// domEle == this</span></code></div></div><div class="container"><div class="line"><code> $( domEle ).css( <span class="string">"backgroundColor"</span>, <span class="string">"yellow"</span> );</code></div></div><div class="container"><div class="line"><code> <span class="keyword">if</span> ( $(<span class="keyword">this</span>).is( <span class="string">"#stop"</span> ) ) {</code></div></div><div class="container"><div class="line"><code> $( <span class="string">"span"</span> ).text( <span class="string">"Stopped at div index #"</span> + index );</code></div></div><div class="container"><div class="line"><code> <span class="keyword">return</span> <span class="literal">false</span>;</code></div></div><div class="container"><div class="line"><code> }</code></div></div><div class="container"><div class="line"><code> });</code></div></div><div class="container"><div class="line"><code> });</code></div></div><div class="container"><div class="line"><code> </code></div></div><div class="container"><div class="line"><code><span class="tag"></<span class="title">script</span>></span></code></div></div><div class="container"><div class="line"><code> </code></div></div><div class="container"><div class="line"><code><span class="tag"></<span class="title">body</span>></span></code></div></div><div class="container"><div class="line"><code><span class="tag"></<span class="title">html</span>></span></code></div></div></pre>
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</td>
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</tr>
|
||
</tbody>
|
||
</table>
|
||
</div>
|
||
<h4>Demo:</h4>
|
||
<div class="demo code-demo"></div>
|
||
</div></section>
|
||
</div></article> </div>
|
||
</article> |