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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<form>
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Male: <input id="male" type="radio" name="Sex" value="Male" />
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<br />
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Female: <input id="female" type="radio" name="Sex" value="Female" />
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</form> 
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<script type="text/javascript">
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document.getElementById('male').focus();
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</script>
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</body>
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</html>
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