js右下角广告[兼容]

<div style="position:absolute;right:0;width: 300px; height:280px; text-align:right; font-size:14px; line-height:22px; color:#000;" id="rb_ad">
<!--注意，height,280,和下面-260的，需要根据图片大小做个调整，本测试图为300x250大小-->
  <a href="javascript:close_rbad();" target="_self">关闭</a><br />
  <img src="/images/AWt3tZQiel6.jpg"" border="0">
</div>
<script language="JavaScript" type="text/javascript">
function rightBottomAd(){
  var abc = document.getElementById("rb_ad");
  var scrollTop=document.documentElement.scrollTop??document.body.scrollTop;
  var clientHeight=document.documentElement.clientHeight;
  abc.style.top = scrollTop + clientHeight-260+"px";
  setTimeout(function(){rightBottomAd();},100);
}
rightBottomAd();
function close_rbad(){
  document.getElementById("rb_ad").style.display="none";
}
</script>