js右侧漂浮广告的小例子

<script language="javascript" type="text/javascript">
var w3c = (document.getelementbyid) ? true : false;
var agt = navigator.useragent.tolowercase();
var ie = ((agt.indexof("msie") != -1) && (agt.indexof("opera") == -1) && (agt.indexof("omniweb") == -1));
var mymovey = new number();
function ietruebody(){
return (document.compatmode && document.compatmode!="backcompat") ? document.documentelement : document.body;
}
function getscrolltop(){
return ie ? ietruebody().scrolltop : window.pageyoffset;
}
</script>

<style type="text/css">
body {
margin:0px;
padding:0px;
font-size: 12px;
height:100%;
}
</style>
<div style="height:1500px; background:#eee; ">右侧漂浮</div>
<!--右侧漂浮qq开始-->
<div style="width:790px;margin:auto;">
<div style="float:right;">
    <div id=backi style="z-index:2;width: 106px; position: absolute; top: 50px; height:auto">
      <img src="qq.jpg" width="106" height="205" />
    </div>
    <script language="javascript1.1">
    //右侧漂浮广告代码
    function heartbeat(){
     diffy=getscrolltop();
     mymovey += math.floor((diffy-document.getelementbyid('backi').style.top.replace("px","")+50)*0.1);
     document.getelementbyid('backi').style.top = mymovey+"px";
    }
    window.setinterval("heartbeat()",1);
   </script>
</div>
</div>
<!--右侧漂浮qq结束-->