var rollspeed=30 
   rolllink2.innerHTML=rolllink1.innerHTML //克隆rolllink1为rolllink2 
   
   var MyMar=setInterval(Marquee,rollspeed) //设置定时器 
   rolllink.onmouseover=function() {clearInterval(MyMar)}//鼠标移上时清除定时器达到滚动停止的目的 
   rolllink.onmouseout=function() {MyMar=setInterval(Marquee,rollspeed)}//鼠标移开时重设定时器 
  
   function Marquee(){ 
   if(rolllink2.offsetWidth-rolllink.scrollLeft<=0)
   { //当滚动至rolllink1与rolllink2交界时 
      rolllink.scrollLeft-=rolllink1.offsetWidth  //rolllink跳到最顶端 
      }
   else{ 
      rolllink.scrollLeft++
   } 
   }