手动切换时加入延时，并没有效果，能帮我看看如何写吗？
<!doctype html>
<html>
<head>
<meta charset="UTF-8">
<title>Document</title>
<style>
*{margin:0;
padding:0;
list-style:none;}
.wrap{height:170px;
width:490px;
overflow: hidden;
position: relative;
margin:10px auto;}
.wrap ul{position:absolute;}
.wrap ul li{height:170px;
cursor:pointer;}
.wrap ol{position:absolute;
right:2px;
bottom:5px;}
.wrap ol li{height:20px;
width: 20px;
background:#ccc;
border:solid 1px #666;
box-shadow:2px 2px 2px grey;
border-radius:5px;
margin-left:5px;
color:#000;
float:left;
line-height:20px;
text-align:center;
cursor:pointer;}
.wrap ol .on{background:#E97305;
color:#fff;}
</style>
<script type="text/javascript">
window.onload=function(){
var wrap=document.getElementById('wrap');
var pics=document.getElementById('pic').getElementsByTagName("li");
var lists=document.getElementById('list').getElementsByTagName('li');
//图片轮播
var index=0;
var timer=null;
timer=setInterval(function(){
index++;
if(index>=lists.length){
index=0;
}
for(var j=0;j<lists.length;j++){
lists[j].className="";
pics[j].style.display="none";
}
lists[index].className="on";
pics[index].style.display="block";
},2000);
//鼠标滑过、滑出事件
for(var i=0;i<lists.length;i++){
lists[i].id=i;
lists[i].onmouseover=function(){
clearInterval(timer); //必须清除定时器！
//延时切换
if(timer){
clearTimeout(timer);
}
var that=this;
timer=setTimeout(function(){
for(var j=0;j<lists.length;j++){
lists[j].className="";
pics[j].style.display="none";
}
lists[that.id].className="on";
pics[that.id].style.display="block";
},500);
index=this.id;
/*
*for(var j=0;j<lists.length;j++){
lists[j].className="";
pics[j].style.display="none";
}
lists[this.id].className="on";
pics[this.id].style.display="block";
index=this.id; //解决鼠标离开后跳栏的问题！！很重要！
*/
}
pics[i].onmouseover=function(){
clearInterval(timer);
}
lists[i].onmouseout=function(){
timer=setInterval(function(){
index++;
if(index>=lists.length){
index=0;
}
for(var j=0;j<lists.length;j++){
lists[j].className="";
pics[j].style.display="none";
}
lists[index].className="on";
pics[index].style.display="block";
},2000);
}
pics[i].onmouseout=function(){
timer=setInterval(function(){
index++;
if(index>=lists.length){
index=0;
}
for(var j=0;j<lists.length;j++){
lists[j].className="";
pics[j].style.display="none";
}
lists[index].className="on";
pics[index].style.display="block";
},2000);
}
}
}
</script>
</head>
<body>
<div id='wrap'>
<ul id="pic">
<li><img src="http://img1.sycdn.imooc.com//54111cd9000174cd04900170.jpg" alt=""></li>
<li><img src="http://img1.sycdn.imooc.com//54111dac000118af04900170.jpg" alt=""></li>
<li><img src="http://img1.sycdn.imooc.com//54111d9c0001998204900170.jpg" alt=""></li>
<li><img src="http://img1.sycdn.imooc.com//54111d8a0001f41704900170.jpg" alt=""></li>
<li><img src="http://img1.sycdn.imooc.com//54111d7d00018ba604900170.jpg" alt=""></li>
</ul>
<ol id="list">
<li>1</li>
<li>2</li>
<li>3</li>
<li>4</li>
<li>5</li>
</ol>
</div>
</body>
</html>
