无衔接js滚动

<div id=demo style=overflow:hidden;height:9;width:232;>
<div id=demo1>
1<br/>1<br/>1<br/>1<br/>1<br/>1<br/>1<br/>1<br/>1<br/>1<br/>1<br/>1<br/>1<br/>1<br/>
</div>
<div id=demo2></div>
</div>
<script>
var speed=50
demo2.innerHTML=demo1.innerHTML
function Marquee(){
if(demo2.offsetTop-demo.scrollTop<=0)
demo.scrollTop-=demo1.offsetHeight
else{
demo.scrollTop++
}
}
var MyMar=setInterval(Marquee,speed)
demo.onmouseover=function() {clearInterval(MyMar)}
demo.onmouseout=function() {MyMar=setInterval(Marquee,speed)}
</script>