javascript count number
<pre><code>&lt;html&gt;
&lt;head&gt;
&lt;script type="text/javascript"&gt;
var c=0;
var t;
var timer_is_on=0;

function timedCount()
{
document.getElementById('txt').value=c;
c=c+1;
t=setTimeout("timedCount()",30);
}

function doTimer()
{
if (!timer_is_on)
  {
  timer_is_on=1;
  timedCount();
  }
}
&lt;/script&gt; 
&lt;/head&gt;

&lt;body&gt;
&lt;form&gt;
&lt;input type="button" value="Start count!" onClick="doTimer()"&gt;
&lt;input type="text" id="txt"&gt;
&lt;/form&gt;
&lt;p&gt;Click on the button above. The input field will count forever, starting at 0.&lt;/p&gt;
&lt;/body&gt;
&lt;/html&gt;
</code></pre>

<p>How can I modify this code to let it stop at 100?
Thanks!</p>
