SOURCE CODE:
<form name = "form1">
<input type="button" value="CAPS ON"
name="btn1" onClick="changeit()">
</form>

<script language = "javascript">
function changeit(){
if (document.form1.btn1.value == "CAPS ON")
   document.form1.btn1.value="CAPS OFF";
else
   document.form1.btn1.value="CAPS ON";
}
</script>