实例代码“Ctrl+/”提示“F11/ESC”全屏 返回 格式化 恢复 运行
​x
 
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<!DOCTYPE html>
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<html>
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<body>
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​
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<p id="demo"></p>
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​
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<script>
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document.getElementById("demo").innerHTML =
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typeof undefined + "<br>" +
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typeof null + "<br>" +
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(null === undefined) + "<br>" +
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(null == undefined);
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</script>
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​
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</body>
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</html>
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