js分组求和

后端返回的数据是所有的,但是前端需要的数据是需要分组并且进行计算求和的

// 数组分组求和
  let groupSum = {
    groupBy: function (array, callback) {
      return new Promise((resolve) => {
        let groups = {};
        array.forEach(item => {
          let group = JSON.stringify(callback(item));
          groups[group] = groups[group] || [];
          groups[group].push(item);
        });
        let res = Object.keys(groups).map(group => {
          return groups[group];
        });
        resolve(res)
      })
    },
    getSum: function (arr,bykey) {
      return new Promise((resolve) => {
        let res = this.groupBy(arr, function (item) {
          return item.shopId
        }).then(res => {
          console.log(res)
          let resultSum = res.map(item => {
            let sum = item.reduce((total, curr) => {
              return total + curr[bykey]
            }, 0);
            return sum
          })
          return resultSum
        })
        resolve(res)
      })
    }
  }
  let testArr = [
    { shopId: 1, shopName: '测试', money: 0, },
    { shopId: 2, shopName: '123', money: 1 },
    { shopId: 1, shopName: '测试', money: 2 },
    { shopId: 1, shopName: '测试', money: 3 },
    { shopId: 2, shopName: '123', money: 4 },
    { shopId: 1, shopName: '测试', money: 5 },
    { shopId: 2, shopName: '123', money: 6 },
  ]
  groupSum.getSum(testArr,'money').then(res => {
    console.log(res)
  }).catch(err => {
    console.log(err)
  })