如何将每月的账单总和统计

Question

array:[

            {

                "tradeTime":[

                    {

                        "amount":5000,

                        "goodsInfo":"翡翠城租金",

                        "tradeTime":"2019-04-20"

                    },

                    {

                        "amount":1200,

                        "goodsInfo":"五联西苑租金",

                        "tradeTime":"2019-04-25"

                    },

                    {

                        "amount":200,

                        "goodsInfo":"爱与家宾馆",

                        "tradeTime":"2019-04-30"

                    }

                ]

            },

            {

                "tradeTime":[

                    {

                        "amount":3800,

                        "goodsInfo":"丁香花园",

                        "tradeTime":"2019-05-20"

                    },

                    {

                        "amount":2500,

                        "goodsInfo":"滨兴小区",

                        "tradeTime":"2019-05-28"

                    }

                ]

            },

            {

                "tradeTime":[

                    {

                        "amount":2800,

                        "goodsInfo":"滨苑小区",

                        "tradeTime":"2019-06-08"

                    }

                ]

            }

        ]

Answer 1

arr.map((item) => {
  if(item.tradeTime[0]) {
    let amount = item.tradeTime.reduce((total, item1) => {
                   return total + item1.amount
                 }, 0)
    return {
      month: item.tradeTime[0].tradeTime.slice(0, 7),
      amount: amount
    }
  }
})