wxml代码:
<scroll-view scroll-x="true" scroll-with-animation class="horizontal" scroll-left="{{scroll}}" id="horizontal">
  <view class="tabs">
    <view class="tab {{active==index?'activeTab':''}}" wx:for="{{list}}" wx:key="index" bindtap="getItem" data-index="{{index}}" id="item-{{index}}">{{item.name}}</view>
    <view class='line' id="line" style="left:{{list[active].offsetLeft}}px;width:{{list[active].width}}px;"></view>
  </view>
</scroll-view>
js部分
  data: {
    list: [{
        id: "0",
        name: "测试"
      },
      {
        id: "0",
        name: "测试测试"
      },
      {
        id: "0",
        name: "测试测试测试"
      },
    ],
  }
  传入list给list增加offsetLeft和width属性
 initItem(e) {
    return new Promise((resolve, reject) => {
      e.forEach((item, index) => {
        let view = wx.createSelectorQuery().select("#item-" + index)
        view.boundingClientRect(res => {
          item.offsetLeft = res.left
          item.width = res.width
        }).exec()
      })
      resolve(e)
    })
  },
  在生命周期onReady初始化打印res可以，res[0]就不行，昨天我问了下是异步问题，所以加了promise，但是.then还是打印res[0]为未定义。求大佬解决
万分感谢
    this.initItem(this.data.list).then(res=>{
      console.log(res)
      console.log(res[0])
    })