<style type="text/css">
*{ margin:0px auto; padding:0px}
#kuang{ width:200px; height:10px; border:1px solid #60F;}
#jindu{ height:10px; background-color:#F03; float:left}
</style>
</head>
<body>
<br />
<div id="kuang">
<div id="jindu" style="width:0px"></div>
</div>
<script type="text/javascript">
window.setTimeout("jindu()",30);
//调一下进度前进1%
function jindu()
{
//获取进度div的宽度
var div = document.getElementById("jindu");
//获取到的是字符串"0px"
var str = div.style.width;
//处理字符串获取数字
var cd = str.substr(0,str.length-2);
//判断长度是否到最大值
if(cd<200)
{
//将长度转为整数加2
var cd = parseInt(cd)+2;
//让进度的DIV长度变为cd
div.style.width = cd+"px";
//调用自身
window.setTimeout("jindu()",30);
}
}
</script>
原文：http://www.cnblogs.com/qdlj/p/6188313.html