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<!DOCTYPE html>
<html>
<body>
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<h1>JavaScript 数字</h1>
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<h2>Number.Nan 属性</h2>
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<p>Number.NaN 返回 NaN ("Not a Number")：</p>
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<p id="demo"></p>
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<script>
let x = Number.NaN;
document.getElementById("demo").innerHTML = x;
</script>
​
</body>
</html>
​