1  var ScrollMiddle = {
 2          'Odiv':document.getElementById('comment'), // 目标DOM
 3          'Oli': document.getElementById('comment').getElementsByTagName('li'),
 4          'times':30,            // 配置滚动时间
 5          'delay':1000,        // 配置暂停的时间
 6          inint:function(){
 7              this.size = this.Oli.length;
 8              this.height = 59;
 9              this.countHeight =this.size * this.height;
10              this.Odiv.innerHTML+=this.Odiv.innerHTML;
11              this.timer = null;
12          },
13          scroll:function(){
14              var _this = this;
15              _this.inint();
16              function scrolls(){
17
18                  var scrollValue = _this.Odiv.scrollTop;
19                  var sub_timer = null;
20                  var num=0;
21                  if(scrollValue>=_this.countHeight){
22                      _this.Odiv.scrollTop = 0;
23                  }else{
24                      _this.Odiv.scrollTop++;
25                      if(scrollValue%_this.height==0){
26                          clearInterval(_this.timer)
27                          function delay(){
28                              num++;
29                              if(num==3){
30                                  num=0;
31                                  clearInterval(sub_timer);
32                                  sub_timer = null;
33                                  clearInterval(_this.timer)
34                                  _this.timer = setInterval(scrolls,_this.times);
35                                  return false;
36                              }
37                          }
38                          sub_timer = setInterval(delay,_this.delay)
39                      }
40                  }
41              }
42              this.timer = setInterval(scrolls,_this.times);
43          }
44      }

ScrollMiddle.scroll();

<ul id="comment"><li></li>......
</ul>

#comment{width:200px;height:200px;overflow:hidden;
}