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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<body>
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<script type="text/javascript">
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var Month=30;
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if (Month < 1 || Month > 12)
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{
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Month = Number.NaN;
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}
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document.write(Month);
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</script>
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</body>
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</html>
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