Untitled

<html>

<head>

<script type="text/javascript">
counter=0;
function incCounter(lala)
{
counter=counter+1;
message.value=counter;
if (counter == 20)
    {
    alert("Clicked the button too many times");
    }
}
</script>

</head>

<body>

<h1>Button Example</h1>
<form>
<input type="text" readonly="yes" size="30" id="message" value="Button has not yet been pressed" />
<input type="button" value="Click Me" onclick="incCounter(this.form)"/>
</form>

</body>

</html>