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 id="myForm">
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<select id="mySelect">
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  <option id="apple">Apple</option>
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  <option id="orange">Orange</option>
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  <option id="pineapple">Pineapple</option>
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  <option id="banana">Banana</option>
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</select>
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</form>
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<p>The id of the form is:
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<script type="text/javascript">
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document.write(document.getElementById("apple").form.id)
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</script>
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</p>
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</body>
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</html>
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