基于jquery的返回顶部效果（兼容IE6）

<div class="scroll"></div> 
<script type="text/javascript" src="../skins/css/jQuery.js" charset="UTF-8"></script> 
<script type="text/javascript" src="../skins/css/top.js" charset="UTF-8"></script>

.scroll{ 
background:url(../image/scroll.gif) no-repeat center top transparent; 
bottom:100px; 
cursor:pointer; 
height:67px; 
width:18px; 
position:fixed; 
_position:absolute; /*兼容IE6*/ 
_top: expression(eval(document.documentElement.scrollTop)+700); /*700为图片距离顶部的设定距离，可以修改。不加700则图片紧贴在顶部滚动*/ 
} 
html{_text-overflow:ellipsis;} /*解决IE6下图片抖动*/

$(document).ready(function(){ 
var show_delay; 
var scroll_left=parseInt((document.body.offsetWidth-960)/2)+961; //960为页面宽度 
$(".scroll").click(function (){ 
document.documentElement.scrollTop=0; 
document.body.scrollTop=0; 
}); 
$(window).resize(function (){ 
scroll_left=parseInt((document.body.offsetWidth-960)/2)+961; 
$(".scroll").css("left",scroll_left); 
}); 
reshow(scroll_left,show_delay); 
}); 
function reshow(marign_l,show_d) { 
$(".scroll").css("left",marign_l); 
if((document.documentElement.scrollTop+document.body.scrollTop)!=0) 
{ 
$(".scroll").css("display","block"); 
} 
else 
{ 
$(".scroll").css("display","none");} 
if(show_d) window.clearTimeout(show_d); 
show_d=setTimeout("reshow()",500); 
}