parameters. Do it like this:
<button id="1" onClick="reply_click(
this.id)">B1</button> <button id="2" onClick="reply_click(
this.id)">B2</button> <button id="3" onClick="reply_click(
this.id)">B3</button> <script type="text/javascript"> function reply_click(clicked_id) { alert(clicked_id); } </script>