js图片轮播左右滚动

#scroll{width:800px; height:150px; margin:10px auto; position:relative;overflow:hidden;}
#scroll ul{position:absolute; left:-16px;; top:-5px;}
#scroll ul li{float:left; width:200px; height:150px; list-style:none; border:#CCC 1px solid;}
#scroll ul li img{width:100%; height:150px;}
window.onload=function(){
var oDiv=document.getElementByIdx_x('scroll');
var oUl=oDiv.getElementsByTagName_r('ul')[0];
var aLi=oUl.getElementsByTagName_r('li');
var Timer=null;
var speed=2;
oUl.innerHTML=oUl.innerHTML+oUl.innerHTML;
oUl.style.width=aLi[0].offsetWidth*aLi.length+'px';
function move(){
if(oUl.offsetLeft<-oUl.offsetWidth/2)    //向左滚动
{
oUl.style.left='0';
}
  else  if(oUl.offsetLeft>0)          //向右滚动
{
oUl.style.left=-oUl.offsetWidth/2+'px';
} 
  
      //向左滚动
oUl.style.left=oUl.offsetLeft+speed+'px'; 
}
Timer=setInterval(move,30)
oDiv.onmouseover=function(){            //鼠标点击停止
clearInterval(Timer);
};
oDiv.onmouseout=function(){             //鼠标离开继续
Timer=setInterval(move,30);
}
 document.getElementsByTagName_r('a')[0].onclick=function(){
 speed=-2;
 }
       document.getElementsByTagName_r('a')[1].onclick=function(){
 speed=2;
 }
};