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

<h2>JavaScript 数字</h2>

<p>调用 myMethod() 来显示一个数字的半值:</p>

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

<script>
Number.prototype.myMethod = function() {
  return this.valueOf() / 2;
};

let n = 55;
document.getElementById("demo").innerHTML = n.myMethod();
</script>

</body>
</html>
运行结果: