数字那里滑过怎么都没效果了么？
var wrap=document.getElementById('wrap');
var pic=document.getElementById('pic');
var list=document.getElementById('list').getElementsByTagName('li');
var index=0;
var timer=null;
for(var i = 0; i < list.length; i++){
list[i].id = i;
list[i].onmouseover = function(){
for(var j = 0; j < list.length; j++){
list[i].className = '';
}
list[this.id].className = 'on';
}
}
