comma

$('form input:checkbox:checked').each(function() {
		var id = $(this).val();
		var div_id = "#tr_"+id ;
		contact_id_str += id + ',';
		//if last iteration, don't include the comma
	});

//fintal result should look like
contact_id_str = "1, 2, 3, 4";

//instead of
contact_id_str = "1, 2, 3, 4,";//i don't want the last comma