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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<html>
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<head>
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<script type="text/javascript" src="/js/jquery.js"></script>
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<script type="text/javascript">
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i=0;
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$(document).ready(function(){
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  $("input").keypress(function(){
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    $("span").text(i+=1);
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  });
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});
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</script>
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</head>
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<body>
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Enter your name: <input type="text" />
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<p>Keypresses:<span>0</span></p>
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</body>
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</html>
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​