兼容IE和Firefox火狐的上下、左右循环无间断滚动JS代码

<style type="text/css" media="all">
.d1{
margin:10px auto;
width:200px;
background-color:#CCCCCC;
height:20px;
overflow:hidden;
white-space:nowrap;
}
.d2{
margin:0px auto;
background-color:#FF9933;
}
.div2{
width:auto;
height:20px;
font-size:12px;
}
</style>
<script language="javascript" type="text/javascript">
var s,s2,s3,s4,timer,i=0;
function init(){
s=getid("div1");
s2=getid("div2");
s3=getid("div3");
s4=getid("div4");
s4.innerHTML=s3.innerHTML;
s2.style.width=s.offsetWidth+"px";
s2.style.height=s.offsetHeight+"px";
timer=setInterval(mar,30)
}
function mar(){
//s2.innerHTML=s.scrollLeft;
if(s3.offsetWidth<=s.scrollLeft){
s.scrollLeft-=s3.offsetWidth;
}else{s.scrollLeft++;}
}
function getid(id){
return document.getElementById(id);
}
window.onload=init;
</script>
<div class="d1" id="div1">
<span class="div2" id="div3"> 余志国网站设计工作室提供专业的外贸网站建站服务。</span>
<span id="div4" class="div2"></span>
</div>
<div class="d2" id="div2"></div>