案例：javascript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">
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function isEventCancelable(event)
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  {
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  alert(event.cancelable);
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  }
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</script>
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</head>
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​
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<body onmousedown="isEventCancelable(event)">
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​
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<p>Click somewhere in the document. An alert box will tell if the event is a cancelable event.</p>
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​
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</body>
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</html>
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​