本文实例讲述了JS采用绝对定位实现回到顶部效果。分享给大家供大家参考，具体如下：
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd" <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>绝对定位回到顶部按钮</title> <style type="text/css"> body{margin:0px;padding:0px;height:2500px;background:#6f0024;} #div1{width:120px;height:34px;right:4px;bottom:5px;cursor:pointer;background:url(images/ToTop.png) no-repeat;position:fixed;_position:absolute;display:none;} </style> <script type="text/javascript"> //绝对定位隐藏显示 function getScroll(id){ var obj = document.getElementById(id); var timer = null; positionFixed(obj); if(obj){ obj.style.display = 'none'; window.onscroll=function(){ getScrollTop() > 0 ? obj.style.display = "block" : obj.style.display = "none"; } obj.onclick=function(){ var timer = setInterval(sMove,10); function sMove(){ setScrollTop(getScrollTop() / 1.5); if(getScrollTop() < 1)clearInterval(timer); } } } } //判断IE6 function positionFixed(obj){ var iE6 = !-[1,] && !window.XMLHttpRequest; if(obj){ var top = obj.offsetTop; if(iE6){ document.documentElement.style.textOverflow = "ellipsis"; obj.style.position = "absolute"; obj.style.setExpression("top", "eval(documentElement.scrollTop + " + top + ') + "px"'); } } } //获取滚动条Top function getScrollTop(){ return document.documentElement.scrollTop || document.body.scrollTop; } //回到顶部 function setScrollTop(value){ document.documentElement.scrollTop = value; document.body.scrollTop = value; } window.onload = function(){ getScroll('div1'); }; </script> </head> <body> <div id="div1"></div> </body> </html>
希望本文所述对大家JavaScript程序设计有所帮助。