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<!doctype html> <html> <head> <meta charset="utf-8"> <title>无标题文档</title> <style> #wrap{ height:2000px; background:pink; position:relative; } #ontop{ position:absolute; bottom:0px; right:0px; background:red; color:#FFF; font-weight:bold; height:100px; width:100px; line-height:100px; text-align:center; cursor:pointer; } </style> <script type="text/javascript"> window.onload = function () { var otop = document.getElementById(‘ontop‘); var timer = null; otop.onclick = function () { timer = setInterval(function() { document.body.scrollTop -= 50; document.documentElement.scrollTop -= 50; if(document.body.scrollTop == 0 && document.documentElement.scrollTop == 0 ) { clearInterval(timer); } },20) }; }; </script> </head> <body> <div id="wrap"> <span id="ontop">回到顶部</span> </div> </body> </html>
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原文地址：http://www.cnblogs.com/mayufo/p/4208100.html
