get id of clicked element javascript

1<button id="3" onClick="reply_click(this.id)">B3</button>
2    
3<script type="text/javascript">
4  function reply_click(clicked_id)
5  {
6      alert(clicked_id);
7  }
8</script>

1<button id="1" onClick="reply_click(this.id)">B1</button>
2<button id="2" onClick="reply_click(this.id)">B2</button>
3<button id="3" onClick="reply_click(this.id)">B3</button>
4    
5<script type="text/javascript">
6  function reply_click(clicked_id)
7  {
8      alert(clicked_id);
9  }
10</script>