jquery textarea 자동 늘어났다 줄어드는 방법-2

<Script language="JavaScript">
 function memoheight(){
  if (event.keyCode == 13){
   var etcmemo = $("#memo").val();
   var em_index = etcmemo.split('\n');
   var etcmemo_row = (em_index.length * 1) +1;
   memo_l_height = (18 * (etcmemo_row * 1)) + 4;
   memo_r_height = ((memo_l_height * 1) + 4);
   memo_height = (18 * (etcmemo_row * 1));

   $("#etc_memo").attr('style', 'height:'+memo_height+'px;width:95%;border:1px solid #D4DBE4;');
  }

 

  if (event.keyCode == 8 || event.keyCode == 46){
   var etcmemo = $("#etc_memo").val();
   var em_index = etcmemo.split('\n');
   var etcmemo_row = (em_index.length * 1);
   if (etcmemo_row > 0){
    memo_l_height = (18 * (etcmemo_row * 1)) + 4;
    memo_r_height = ((memo_l_height * 1) + 4);
    memo_height = (18 * (etcmemo_row * 1));

    $("#etc_memo").attr('style', 'height:'+memo_height+'px;width:95%;border:1px solid #D4DBE4;');
   }
  }
 }

</script>

 

<textarea name="memo" id="memo" style="width:95%;height:20px;border:1px solid #D4DBE4;" onKeyDown="javascript:memoheight();"><%=etc_memo%></textarea>

 

딱 2줄만 바꾼 업그레이드 버전