网页返回顶端的JS代码 

 1 <script >
 2 $(function(){
 3 $(window).bind("scroll", function(){ 
 4 var sh = $(document).scrollTop();
 5 if(isie6Fun()){
 6 var wh = $(window).height();
 7 var ssss= wh*0.8+sh;
 8 $("#returntop").css("top",ssss+"px");
 9 }
10 if($("#returntop").is(":visible")){
11 if(sh<260){
12 $("#returntop").hide();
13 }
14 }
15 if($("#returntop").is(":hidden")){
16 if(sh>260){
17 $("#returntop").show();
18 }
19 }
20 }); 
21 $("#returntop").click(function(){
22 $(document).scrollTop(0);
23 });
24 });
25 function isie6Fun(){
26 var userAgent = navigator.userAgent.toLowerCase();
27 var browserId = userAgent.match(/(firefox|chrome|safari|opera|msie)/)[1];
28 Var browserVersion = (userAgent.match(new RegExp('.+(?:version)[\/: ]([\\d.]+)')) || userAgent.match(new RegExp('(?:'+browserId+')[\/: ]([\\d.]+)')) || [0,'0'])[1];
29 var isIe6 = (browserId + browserVersion == "msie6.0");
30 return isIe6;
31 }
32 </script>

<a id="returntop" href="javascript:void(0)" style="display:none;" title="返回顶部"></a>

 

posted @ 2013-06-04 16:19  菜-鸟  阅读(200)  评论(0)  编辑  收藏  举报