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<!DOCTYPE html>
<html>
<body>
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<h1>JavaScript 数字</h1>
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<h2>Number.isNaN() 方法</h2>
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<p>如果值为 NaN 且数据类型为 Number，则 Number.isNaN() 返回 true，否则返回 false。</p>
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<p id="demo"></p>
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<p>Internet Explorer 11（或更早版本）不支持 Number.isNaN()。</p>
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<script>
let result =
"Is 123 NaN? " + Number.isNaN(123) + "<br>" +
"Is -123 NaN? " + Number.isNaN(-1.23) + "<br>" +
"Is '123' NaN? " + Number.isNaN('123') + "<br>" +
"Is 0/0 NaN? " + Number.isNaN(0 / 0);
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document.getElementById("demo").innerHTML = result;
</script>
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</body>
</html>
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