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<!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 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); document.getElementById("demo").innerHTML = result; </script> </body> </html>