小程序 绑定class

<view class="list-wrapper">
      <view class="list-top">
         <view data-num="1" class="list-menu list-menu1 {{_num==1?‘cur‘:‘‘}}" bindtap="menuClick">头条</view>
         <view data-num="2" class="list-menu list-menu2 {{_num==2?‘cur‘:‘‘}}" bindtap="menuClick">活动</view>
         <view data-num="3" class="list-menu list-menu3 {{_num==3?‘cur‘:‘‘}}" bindtap="menuClick">公告</view>
      </view>
</view>

menuClick:function(e){
      this.setData({
         _num:...
      })
  },