纵向滚动js代码

<div id=demo style=overflow:hidden;height:100;width:20;
background:#214984;color:#ffffff>
<div id=demo1>
 <img src="images/smilies/icon_mrgreen.gif">
 <img src="images/smilies/icon_mrgreen.gif">
 <img src="images/smilies/icon_mrgreen.gif">
 <img src="images/smilies/icon_mrgreen.gif">
 <img src="images/smilies/icon_mrgreen.gif">
 <img src="images/smilies/icon_mrgreen.gif">
 <img src="images/smilies/icon_mrgreen.gif">
 <img src="images/smilies/icon_mrgreen.gif">
 <img src="images/smilies/icon_mrgreen.gif">
 </div>
 <div id=demo2></div>
 </div>
   <script>
   var speed=30
   demo2.innerHTML=demo1.innerHTML //克隆demo1为demo2
   function Marquee(){ //当滚动至demo1与demo2交界时
if(demo2.offsetTop-demo.scrollTop<=0)  
demo.scrollTop-=demo1.offsetHeight //demo跳到最顶端
else{
demo.scrollTop++
   }
   }
   var MyMar=setInterval(Marquee,speed)//设置定时器
//鼠标移上时清除定时器达到滚动停止的目的
   demo.onmouseover=function() {clearInterval(MyMar)}
//鼠标移开时重设定时器
   demo.onmouseout=function(){MyMar=setInterval(Marquee,speed)}
</script>