弹性回到顶部js代码

JS部分

function goTopEx(){
        var obj=document.getElementById("goTopBtn");
        function getScrollTop(){
            return document.documentElement.scrollTop || window.pageYOffset || document.body.scrollTop; 
            }
        function setScrollTop(value){
            (/(chrome|version)/i).test(navigator.userAgent) ? document.body.scrollTop = value : document.documentElement ? document.documentElement.scrollTop = value : document.body.scrollTop = value;
            }   
            window.onscroll=function(){getScrollTop()>0?obj.style.display="":obj.style.display="none";}
            obj.onclick=function(){
            var goTop=setInterval(scrollMove,10);
            function scrollMove(){
                    setScrollTop(getScrollTop()/1.1);
                    if(getScrollTop()<1)clearInterval(goTop);
                }
        }
    };

CSS部分

#goTopBtn {
    background:url("../images/lanren_top.jpg") no-repeat;
    display:block;
    position: fixed; 
    width: 60px; 
    bottom: 35px; 
    height: 60px; 
    font-size: 12px; 
    cursor: pointer; 
    right: 25px;
    _position: absolute; 
    _right: auto;
    z-index:500;
}

html部分

<div style="display: none" id=goTopBtn></div>
<script type=text/javascript>goTopEx();</script>