div层一直处于页面中间 

<html>
     <head>
         <title>测试</title>
     </head>
 <body>
fdfdfadf
 <table width="200" height="3600" border="1">
<tr>
<td>qqxcxcxzc .dfd...,dsfsd,dfds</td>
</tr>
</table>
 <div id="a" style="POSITION: absolute;border:1px solid red;">11dsfsdf23</div>
 <script>
 function $(id){
         return document.getElementById(id);
 }
     
 function getPageTopScroll(){ 
 var yScroll;
 if (self.pageYOffset) {
 yScroll = self.pageYOffset;
 } else if (document.documentElement && document.documentElement.scrollTop){
 yScroll = document.documentElement.scrollTop;
 } else if (document.body) {
 yScroll = document.body.scrollTop;
 }
 return yScroll;
 }
 
 window.onload=function div(){
   
               var aa=getPageTopScroll();                              
              $("a").style.top=aa+document.body.clientHeight/2;
            setTimeout("div()",100)
             }
 </script>
 </body>
 </html>
posted @ 2012-08-27 11:41  沐雪架构师  阅读(600)  评论(0)    收藏  举报