js无间断滚动只针对IE

<div id=demo style="overflow:hidden;WIDTH: 235px; HEIGHT: 490px;text-align:left;padding:0px 5px 0px 5px;line-height:20px"> 
<div id=demo1>
sdfsdfsdfsdfds
</div>

<div id=demo2></div>
<div class="w_cont_box"></div>
</div>
</div>
<script> 
var speed=30 
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>