根据字段进行数组分组

  // list数组分组 根据名字
    const groupYear = this.groupBy(list, (item) => {
      return item.year// 按照year进行分组
    })

    groupBy(list, fn) {
      const groups = {}
      list.forEach(function(o) {
        const group = fn(o)
        groups[group] = groups[group] || []
        groups[group].push(o)
      })
      const resData = []
      Object.keys(groups).forEach((key) => {
        resData.push({
          departName: key,
          children: groups[key]
        })
      })
      return resData
    },

 分组后的数据格式