You have try like this.
Solution 1 :
============
<script lanugage=javascript runat=server>
function ontextchange()
{
document.getElementById("lableid").value = "change in text or whatever";
}
</script>
Solution 2 :
============
<script lanugage=javascript runat=server>
function ontextchange()
{
// check if browser is IE
if(ie)
document.getElementById("lableid").innerHTML = "change in text or whatever";
else
document.all('labelid').innerHTML ="hello word"
}
</script>
Hope this will helpful to you.!