javascript 实现页面加载进度条代码

<!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> <TITLE> New Document </TITLE> <meta http-equiv="Content-Type" content="text/html; charset=gb2312" /> <script type="text/javascript"><!-- document.write('<span>加载中，请耐心等待</span><img src="http://files.jb51.net/upload/2010-4/20100411182122592.gif" width="160" height="20" />'); window.onload = function () { document.getElementById('loadbox').style.display="none"; document.getElementById('imglist').style.display="block"; } // --> </script> <style type="text/css"> <!-- body {background-color:#000;} #imglist { display:none;color:#FFFFFF;} #loadbox { width:160px;height:60px; position:absolute;top:50%;left:50%;margin-left:-80px;margin-top:-30px;} #loadbox span {height:30px;display:block;width:160px;text-align:center; color:#FFF; font-size:12px;} --> </style> </HEAD> <BODY> <h1>欧文加油！</h1> <img src="http://img.gxlcms.com//Uploads-s/new/2019-09-17-201917/20100411182122712.jpg" width="500" height="413" /> <img src="http://img.gxlcms.com//Uploads-s/new/2019-09-17-201917/20100411182123800.jpg" width="800" height="600" /> </BODY> </html>
[Ctrl+A 全选 注:如需引入外部Js需刷新才能执行]