我想用javascript做一个下载等待的进度条,怎么做

<title>loadpage</title>
<meta http-equiv=Content-Type content=text/html; charset=gb2312><style type=text/css><!--.unnamed1 {  background-color: #000000}--></style></head><body><table border=0 cellpadding=0 cellspacing=0 width=100% height=100%><tr><form name=loading>      <td align=center>        <p align=center>&nbsp;</p>        <p align=center><font color=#00FF00 size=2></font></p>        <p>
          <input type=text name=chart size=46 style=font-family:Arial; font-weight:bolder;color:#00FF00; background-color:black; padding:0px; border-style:none;>
          <br>
          <br>
          <input type=text name=percent size=46 style=font-family:Arial; color:#00FF00;text-align:center; border-width:medium; border-style:none; class=unnamed1>
          <br>
          <br>
          <font color=#00FF00 size=2 >
          <script>
var bar = 0var line = ||var amount =||count()function count(){bar= bar+2amount =amount + linedocument.loading.chart.value=amountdocument.loading.percent.value=bar+%if (bar<99)
{
setTimeout(count(),100);
}else
{
alert(载入完毕)
window.location = http://www.csdn.net;
}}</script>
         
          <noscript></noscript></font></p>
       
                  </td><!--//-->
</form></tr></table></body></html>