如何在网页上实现进度条

进度条的实现可以通过下面的javascript实现：
<table align="center"><tr><td>
<div style="font-size:8pt;padding:2px;border:solid black 1px">
<span id="progress1">   </span>
<span id="progress2">   </span>
<span id="progress3">   </span>
<span id="progress4">   </span>
<span id="progress5">   </span>
<span id="progress6">   </span>
<span id="progress7">   </span>
<span id="progress8">   </span>
<span id="progress9">   </span>
</div>
</td></tr></table>
<script language="javascript">
var progressEnd = 9;  // set to number of progress <span>'s.
var progressColor = 'blue'; // set to progress bar color
var progressInterval = 1000; // set to time between updates (milli-seconds)

var progressAt = progressEnd;
var progressTimer;
function progress_clear() {
 for (var i = 1; i <= progressEnd; i++) document.getElementById('progress'+i).style.backgroundColor = 'transparent';
 progressAt = 0;
}
function progress_update() {
 progressAt++;
 if (progressAt > progressEnd) progress_clear();
 else document.getElementById('progress'+progressAt).style.backgroundColor = progressColor;
 progressTimer = setTimeout('progress_update()',progressInterval);
}
function progress_stop() {
 clearTimeout(progressTimer);
 progress_clear();
}
progress_update();  // start progress bar
</script>
实现的原理就是通过修改spanid的backgroundColor 值和setTimeout('progress_update()',progressInterval);
定时器函数来实现的。