js实现文字列表无缝滚动效果

<div id="rule">
        <div class="list" id="list">
          <p>用户185****0000  获得xxx优惠券</p>
          <p>用户185****0000  获得xxx优惠券</p>
          <p>用户185****0000  获得xxx优惠券</p>
          <p>用户185****0000  获得xxx优惠券</p>
          <p>用户185****0000  获得xxx优惠券</p>
          <p>用户185****0000  获得xxx优惠券</p>
          <p>用户185****0000  获得xxx优惠券</p>
          <p>用户185****0000  获得xxx优惠券</p>
          <p>用户185****0000  获得xxx优惠券</p>
          <p>用户185****0000  获得xxx优惠券</p>
          <p>用户185****0000  获得xxx优惠券</p>
          <p>用户185****0000  获得xxx优惠券</p>
        </div>
   <div class="list2" id="list2"></div>
</div>

var speed=50;
var list=document.getelementbyid('list');
var list2=document.getelementbyid('list2');
var rule=document.getelementbyid('rule');
list2.innerhtml=list.innerhtml;
function marquee(){
  if(list2.offsettop-rule.scrolltop<=0)
    rule.scrolltop-=list.offsetheight;
  else{
    rule.scrolltop++;
  }
}
var mymar=setinterval(marquee,speed);
rule.onmouseover=function() {clearinterval(mymar)}
rule.onmouseout=function() {mymar=setinterval(marquee,speed)}