微信小程序动态样式

<view class="{{theindex==index?'left-item-active':'left-item'}}" bindtap="changeIndex" data-item="{{item}}"
          data-index="{{index}}">
          {{item.name}}
        </view>
           

changeIndex(e) {
    // console.log(e.currentTarget.dataset.item, e.currentTarget.dataset.index);
    this.setData({
      theindex: e.currentTarget.dataset.index
    })
  },
           

.left-item {
  padding: 15px 5px;
}
.left-item-active{
  padding: 15px 5px;
  background: #fff;
}