​x
 
<html>
<body>
​
<script type="text/javascript">
​
Object.prototype.showValue = function () {
  document.write(this.valueOf());
};
​
var str = "hello";
var iNum = 25;
​
str.showValue();
document.write("<br />")
iNum.showValue();
​
</script>
​
</body>
</html>
​