js实现返回页面顶部功能详解编程语言

// JavaScript Document 
function goTopEx(){ 
        var obj=document.getElementById("goTopBtn"); 
        function getScrollTop(){ 
                return document.documentElement.scrollTop; 
            } 
        function setScrollTop(value){ 
                document.documentElement.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); 
                } 
        } 
    }