小程序scroll-view点击项自动居中

<scroll-view scroll-x scroll-left="{{scrollLeft}}" scroll-with-animation class="scroll-view">
  <view class="class-item" wx:for="{{classList}}" wx:key="id" bindtap="switchClass">
    <text class="name">{{item.className}}</text>
  </view>
</scroll-view>

onReady(){
  wx.createSelectorQuery().select('.scroll-view').boundingClientRect((rect)=>{
    this.data.scrollViewWidth = Math.round(rect.width)
  }).exec()
},
switchClass(){
  let offsetLeft = e.currentTarget.offsetLeft
  this.setData({
    scrollLeft: offsetLeft - this.data.scrollViewWidth/2
  })
}