Qq suspension code of compatible with all browsers

<script language="JavaScript" type="text/javascript">
lastScrollY=0;
function heartBeat(){ 
var diffY;
if (document.documentElement && document.documentElement.scrollTop)
diffY = document.documentElement.scrollTop;
else if (document.body)
diffY = document.body.scrollTop
else
{}
//alert(diffY);
percent=.1*(diffY-lastScrollY); 
if(percent>0)percent=Math.ceil(percent); 
else percent=Math.floor(percent); 
document.getElementById("ad_left").style.top=parseInt(document.getElementById
("ad_left").style.top)+percent+"px";
document.getElementById("ad_right").style.top=parseInt(document.getElementById
("ad_left").style.top)+percent+"px";
lastScrollY=lastScrollY+percent; 
//alert(lastScrollY);
}
function hidead(num)
{
showad = false;
if(num==1)
document.getElementById("ad_left").style.display="none";
else if(num==2)
document.getElementById("ad_right").style.display="none";
}
var ClosebuttonHtml1 = '<div style="position: absolute;bottom:0px;right:25px;margin:2px;padding:2px;z-index:2000;"><a href="javascript:void(0);" onclick="hidead(1)" style="color:#ffffff;text-decoration:none;font-size:12px;"> Shut down </a></div>';
var ClosebuttonHtml2 = '<div style="position: absolute;bottom:0px;right:25px;margin:2px;padding:2px;z-index:2000;"><a href="javascript:void(1);" onclick="hidead(2)" style="color:#ffffff;text-decoration:none;font-size:12px;"> Shut down </a></div>';
ad1="<div id=/"ad_left/" style='right:10px;POSITION:absolute;TOP:160px;'></div>"
ad2="<DIV id=/"ad_right/" style='right:10px;POSITION:absolute;TOP:160px;'><br><a href='tencent://message/?uin=758541860&Menu=yes'><img height='120' src='../images/qq.gif' border='0' width='110'></a></div>";
document.write(ad1); 
document.write(ad2); 
window.setInterval("heartBeat()",1);
</script>