通过jquery更新数据值

Question

我需要更新两个数据值。  当我点击带有类.messageconv的div时，抓取data-unread_mess_n值并从data-menutop_mess_nr和相同的data-unread_mess_n中减去它。
如果data-menutop_mess_nr == 0的值改变了类。
我无法更新data-unread_mess_n和data-menutop_mess值为什么？

   

$(document).on('click touchstart', '.messageconv', function(e) {
		e.preventDefault();
		messagesNumber($(this));

	});
function messagesNumber(elem) {
		var numMess = elem.parent().data('unread_mess_n');
		var numMessMenutop = $('#menutop_mess_nr').data('menutop_mess_nr');
		if (numMess != 0) {
			elem.children('p').remove();
		}
		var remainingMess = numMessMenutop - numMess;
		$('#menutop_mess_nr').html(remainingMess);
		if (remainingMess == 0) {
			$('#menutop_mess_nr').addClass('bluecount').removeClass('redcount');
		}
		elem.parent().data('unread_mess_n','0');
		$('#menutop_mess_nr').data('menutop_mess_nr',remainingMess);
		
	}

 .messageconv{
  border: 2px solid red;
  height: 50px;
  
  }
 .redcount {
  background: #de2424;
  width:30px;
  }

 .bluecount {
  background: #333399;
  width:30px;
   }

  .redcount:hover {
   background: #ed4747;
   text-decoration: none;
   }

     <script src="http://code.jquery.com/jquery-latest.min.js"></script>
  <a data-unread_mess_n="2" href="5">
 <div class="messageconv">
  test
 <p class="incmessage redcount">2</p></div>
 </a>
 <a data-unread_mess_n="3" href="4">
 <div class="messageconv">
 test1
 <p class="incmessage redcount">3</p></div>
 </a>
 <p data-menutop_mess_nr="5" id="menutop_mess_nr" class="incmessage redcount">5</p>

Answer 1

你可以试试这个

elem.parent().attr('unread_mess_n','0');