案例：jQuery案例     状态：可编辑再运行    进入竖版
 运行结果　
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<!DOCTYPE html>
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<html>
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<head>
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  <script type="text/javascript" src="/js/jquery.js"></script>
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</head>
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​
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<body>
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  <ul class="first">
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     <li class="foo">list item 1</li>
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     <li>list item 2</li>
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     <li class="bar">list item 3</li>
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  </ul>
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  <ul class="second">
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     <li class="foo">list item 1</li>
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     <li>list item 2</li>
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     <li class="bar">list item 3</li>
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  </ul>
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  <script>$('ul.first').find('.foo').css('background-color', 'red')
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    .end().find('.bar').css('background-color', 'green');</script>
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</body>
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</html>
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​