<!-- Start Script Example -->
<script LANGUAGE="JavaScript">
<!-- Begin
function onKeyPress () {
var keycode;
if (window.event) keycode = window.event.keyCode;
else if (e) keycode = e.which;
else return true;
if (keycode == 13) {
alert("Please Click on the Submit button to proceed");
return false
}
return true
}
document.onkeypress = onKeyPress;
//  End -->
</script>
<!-- End Script Example -->

<!-- Start Script Example Visualize -->
<p>Try hitting <b>Enter</b> to continue...</p><br>
<form name="buttons" method="post">
<input type="text">
<input type="submit" value=" Submit ">
</form>     
<!-- End Script Example -->