wxml

<!--pages/test/test.wxml-->
<block wx:for="{{a}}" wx:for-index="father_index" wx:for-item="father_item">

  <view data-index="{{father_index}}">

    <block wx:for="{{father_item}}" wx:for-index="son_index" wx:for-item="son_item">

      <input type="text" wx:if="{{son_item.value!=undefined}}" value="{{son_item.value+father_index+son_index}}" data-index="{{father_index}}" 
      data-len="{{father_item.length}}"
       bindtap="clickHandle" data-son="{{son_index}}" wx:key="{{index}}"
      class="{{son_index == a[father_index][father_item.length - 1].flag?‘active‘:‘‘}}"
      />
    
     
    </block>

  </view>
</block>

js

// pages/test/test.js
Page({

  /**
   * 页面的初始数据
   */
  data: {
    a: [

      [{ value: "a" }, { value: "b" }, { value: "c" }],

      [{ value: "d" }, { value: "e" }, { value: "f" }],

      [{ value: "g" }, { value: "h" }, { value: "i" }]

    ]
  },
  clickHandle(e){
  // console.log(e)
  let parentIndex = e.currentTarget.dataset.index
  let sonIndex = e.currentTarget.dataset.son
  let len = e.currentTarget.dataset.len
  console.log(e)
    this.data.a[parentIndex][len - 1].flag = sonIndex
    console.log( this.data.a)
    let bb = this.data.a
    this.setData({
      a:bb
    })
  },
  /**
   * 生命周期函数--监听页面加载
   */
  onLoad: function (options) {
    let A = this.data.a;
A.map(el=>{
      return el.push({flag:0})
    })
    console.log(A,‘B‘)
    this.setData({
      a:A
    })
   
    console.log(this.data.a,‘jjj‘)
  },

  /**
   * 生命周期函数--监听页面初次渲染完成
   */
  onReady: function () {

  },

  /**
   * 生命周期函数--监听页面显示
   */
  onShow: function () {

  },

  /**
   * 生命周期函数--监听页面隐藏
   */
  onHide: function () {

  },

  /**
   * 生命周期函数--监听页面卸载
   */
  onUnload: function () {

  },

  /**
   * 页面相关事件处理函数--监听用户下拉动作
   */
  onPullDownRefresh: function () {

  },

  /**
   * 页面上拉触底事件的处理函数
   */
  onReachBottom: function () {

  },

  /**
   * 用户点击右上角分享
   */
  onShareAppMessage: function () {

  }
})

wxss

/* pages/test/test.wxss */
.active{
  color: red;
}

效果

小程序双重for循环实现tab切换小demo