탭클릭시 active

<div id="dv">
 <ul>
  <li style="margin:0;" id="dv1" class="active" onclick="javascript:click_item('item_explan');chgOver(1)"><a href="#" class="screen_out">상품상세정보</a></li>
  <li id="dv2" onclick="javascript:click_item('item_use');chgOver(2)"><a href="#" class="screen_out">상품사용후기</a></li>
  <li id="dv3" onclick="javascript:click_item('item_qa');chgOver(3)"><a href="#" class="screen_out">상품문의</a></li>
  <li id="dv4" onclick="javascript:click_item('item_baesong');chgOver(4)"><a href="#" class="screen_out">배송/교환/반품</a></li>
  <div class="clear"></div>
 </ul>
</div>
<script language="JavaScript">
function chgOver(num) {
 for(i=1;i<5;i++) { 
  $("#dv"+i).removeClass("active");
 }
 $("#dv"+num).addClass("active");
}

</script>