演示效果请看渐变效果进度条，具体代码如下：
<!DOCTYPE html>
<html>
<head>
<title>渐变效果进度条</title>
<script language="javascript">
var _Hex = Array("00","01","02","03","04","05","06","07","08","09","0A","0B","0C","0D","0E","0F","10","11","12","13","14","15","16","17","18","19","1A","1B","1C","1D","1E","1F","20","21","22","23","24","25","26","27","28","29","2A","2B","2C","2D","2E","2F","30","31","32","33","34","35","36","37","38","39","3A","3B","3C","3D","3E","3F","40","41","42","43","44","45","46","47","48","49","4A","4B","4C","4D","4E","4F","50","51","52","53","54","55","56","57","58","59","5A","5B","5C","5D","5E","5F","60","61","62","63","64","65","66","67","68","69","6A","6B","6C","6D","6E","6F","70","71","72","73","74","75","76","77","78","79","7A","7B","7C","7D","7E","7F","80","81","82","83","84","85","86","87","88","89","8A","8B","8C","8D","8E","8F","90","91","92","93","94","95","96","97","98","99","9A","9B","9C","9D","9E","9F","A0","A1","A2","A3","A4","A5","A6","A7","A8","A9","AA","AB","AC","AD","AE","AF","B0","B1","B2","B3","B4","B5","B6","B7","B8","B9","BA","BB","BC","BD","BE","BF","C0","C1","C2","C3","C4","C5","C6","C7","C8","C9","CA","CB","CC","CD","CE","CF","D0","D1","D2","D3","D4","D5","D6","D7","D8","D9","DA","DB","DC","DD","DE","DF","E0","E1","E2","E3","E4","E5","E6","E7","E8","E9","EA","EB","EC","ED","EE","EF","F0","F1","F2","F3","F4","F5","F6","F7","F8","F9","FA","FB","FC","FD","FE","FF");
function go()
{
setTimeout('start();',100);
}
var i=0;
function start()
{
if(i++<256)
{
ps.innerHTML += "<span style='display:inline-block; width:1px; height:100%; background-color:#FF"+_Hex[256-i]+"00;'>";
bn.innerHTML = Math.floor(i/2.56)+"%";
setTimeout('start();',10);
}
}
</script>
<style type="text/css">
#ps {
background-color:#ddd;
width:256px;
margin: 1px;
float:left;
height: 18px;
/*overflow: hidden;*/
}
#bn {
width:39px;
margin: 1px;
float:right;
text-align:center;
color:#FFFFFF;
font-family:Arial;
font-size:13px;
}
</style>
</head>
<body onload="go();">
<div style="background-color:black;width:300px;height:20px;">
<div id="ps"></div>
<div id="bn"></div>
</div>
</body>
</html>