检查数字是否非法 - 在线编辑器

          <script>
  document.write(isNaN(123) + "<br>");
  document.write(isNaN(-1.23) + "<br>");
  document.write(isNaN(5 - 2) + "<br>");
  document.write(isNaN(0) + "<br>");
  document.write(isNaN("Hello") + "<br>");
  document.write(isNaN("2005/12/12") + "<br>");
</script>
        