Active button

<div class="menu">
<span class="btactive" ><a href="#"  >buton1</a></span>
<span ><a href="#" >buton2</a></span>
<span ><a href="#" >buton3</a></span>
</div>

<script language="Javascript">
$(document).ready(function() {
$('a[rel*=bt]').each(function() {
	$(this).click(function() {
	var id = $(this).attr('id');
		$('span[id*=sb]').each(function() {
		var spid = $(this).attr('id');
		var check = 's'+id;

			if (spid == check) {
			$(this).addClass('btactive');
			}
			else {
			$(this).removeClass('btactive');
			}
		});
	});
});
});
</script>

<div class="menu">
<span id="sb1" class="btactive"><a href="#" id="b1" rel="bt">buton1</a></span>
<span id="sb2"><a href="#" id="b2" rel="bt">buton2</a></span>
<span id="sb3"><a href="#" id="b3" rel="bt">buton3</a></span>
</div>