在学js时遇到小问题，求解答

Question

 1     <script type="text/javascript">
 2         var mymenu=function(id,speed){
 3             if(this===window)
 4                 return new mymenu(id,speed);
 5             var obj=document.getElementById(id),
 6                 childs=obj.childNodes[1].childNodes;
 7             this.author="NoThinkingGao";
 8             this.menuList=childs;
 9             this.menuNume=childs.length;
10             this.currentIndex=0;
11             this.speed=speed||5000;
12             this.width=100;
13             this.runHandler=null;
14             this.len=this.menuNume;
15         }
16             
17         mymenu.prototype={
18             bindMouse:function(){
19                 for(var i=0;i<this.len;i++){
20                     this.menuList[i].onmouseover=function(i){
21                         this.menuList[1].style.border="1px solid red";
　　　　　　　　　　　　　　　　//上边这行为什么总是不对呢？TypeError: this.menuList is undefined
22                     };
23                 }
24             },
25             action:function(i){
26                 window.alert(this.author+i);
27             },
28             play:function(){
29                 window.alert(this.author);
30             },
31             
32             changeback:function(){
33                 this.menuList[1].style.border="1px solid red";
34             }
35         };
36         window.onload=function(){
37             mymenu("mymenu").bindMouse();
38             mymenu("mymenu").changeback();
39         };
40     </script>

Answer 1

把   this.menuList[1].style.border="1px solid red";改成 this.style.border="1px solid red";试试。。