<!DOCTYPE html>
<html>
<body>
<h1>JavaScript 数字</h1>
<h2>Number.isNaN() 方法</h2>
<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>
<p id="demo"></p>
<p>Internet Explorer 11（或更早版本）不支持 Number.isNaN()。</p>
<script>
let result =
"Is 5-2 NaN? " + Number.isNaN(5-2) + "<br>" +
"Is 0 NaN? " + Number.isNaN(0) + "<br>" +
"Is 'Hello' NaN? " + Number.isNaN('Hello') + "<br>" +"Is '2005/12/12\ NaN? " + Number.isNaN('2005/12/12') + "<br>" +"Is ' ' NaN? " + Number.isNaN('');
document.getElementById("demo").innerHTML = result;</script>
</body>
</html>