javascript问题 求解答？

[无尽追逐]

var new_object = function (){

/**填写代码*/

}

var obj = new_object;
obj.a = 2;
obj.b = 3;
obj.addfunction(); //填写代码让返回结果为5

[CodeVitamin]

var new_object = function (){

/**填写代码*/
this.a=0;
this.b=0;
this.addfunction=function(){
return this.a+this.b;
}
}

[Thinkingjava2010]

[whumr1]

<script language="javascript">
var new_object = function (){

/**填写代码*/
	var a,b;
	

}

	Object.prototype.addfunction = function() {
		return new_object.a + new_object.b;
	}
  
var obj = new_object;
  obj.a = 2;
  obj.b = 3;
  obj.addfunction(); //填写代码让返回结果为5
  alert(obj.addfunction());
  
 
</script>