小程序单独设置数组对象中某一个属性值

如题，js代码如下

page({
  data:{
    list:[{a:1,b:2,c:3},{a:12,b:22,c:32},{a:13,b:23,c:33}],
    test:{aa:1,bb:2,cc:3}
  },
  jian(e){
    let i = e.currentTarget.dataset.index
    let that = this
    let currentDysl = `list[${i}].a`
    this.setData({
       [currentDysl]:parseInt(that.data.list[i].a) - 1
    })
  },
  jia(e){
    this.setData({
      ['test.aa']:22
    })
  }
})