代码示例:(标识:eg_js_number_valueof)
<!DOCTYPE html>
<html>
<body>

<h1>JavaScript 数字方法</h1>

<p>valueOf() 把数字返回为数字:</p>

<p id="demo"></p>

<script>
var x = 123;

document.getElementById("demo").innerHTML = 
  x.valueOf() + "<br>" +
  (123).valueOf() + "<br>" +
  (100 + 23).valueOf();
</script>

</body>
</html>
运行结果: