HTML代码(即需要漂浮的广告)：  <div class="christmas_ad" style="width:155px; height:220px; position:absolute; top:250px; right:25px;">  <a href="javascript:void(0)" ><img src="/themes/mall/wowsai/topics/images/christmas_2012/christmasAcvance.png" border="0" /></a>  </div>    js代码：前提是必须要引入jquery文件  <script type="text/javascript">  $(function(){        $(window).scroll(function(){            var scrollTop = document.body.scrollTop || document.documentElement.scrollTop || 0;            $(".christmas_ad").stop();            var scrollTop2 = (scrollTop+160) - $(".christmas_ad").position().top;            if(scrollTop> 440){                $(".christmas_ad:not(:animated)").animate({top:"+="+scrollTop2+"px"},1000);            }else{                $(".christmas_ad").css("top",370+"px");            }        })    })   </script>