var speed=50;  //设置向上滚动速度
    var dome=document.getElementById("dome");
   var dome1=document.getElementById("dome1");
   var dome2=document.getElementById("dome2");
         function moveTop(){
   dome2.innerHTML=dome1.innerHTML //复制dome1为dome2
   if(dome2.offsetTop-dome.scrollTop<=0)   //当滚动至dome1与dome2交界时
   dome.scrollTop-=dome1.offsetHeight      //dome跳到最顶端
   else{
   dome.scrollTop++
   }
   }
    var MyMar=setInterval(moveTop,speed) //设置定时器
   dome.onmouseover=function() {clearInterval(MyMar)}//鼠标移上时清除定时器达到滚动停止的目的
   dome.onmouseout=function() {MyMar=setInterval(moveTop,speed)}//鼠标移开时重设定时器，继续滚动