Vue获取WdatePicker插件日期的值

<div class="col-xs-2-10">
  <div class="col-xs-2-10" style="width: 100%">
    <div class="col-xs-6 noPadding" style="width: 100%">
     <input class="Wdate form-control form-date certificateEndDate" :id="'certificateEndDate'+index" v-model="item.certificateEndDate" v-on:blur="changeDate(index)"
   onfocus="WdatePicker({skin:'twoer',lang:'#springMessage("common.datePicker")'})">
      </div>
   </div>
 </div>

changeDate: function (index) {
                vm.certificateListShow[index].certificateEndDate = $("#certificateEndDate" + index).val();
            }