W3School TIY
编辑您的代码：
<html> <body> <script type="text/javascript"> var test1="300" var test2="Hello World!" document.write(Number(test1)+ "<br />") document.write(Number(test2)+ "<br />") document.write(isNaN(test1)+ "<br />") document.write(isNaN(test2)) </script> </body> </html>
查看结果: