javascript - 如何根据 Javascript 中的对象键从对象数组添加对象值

Question

我想根据另一个对象键从对象数组中添加一些对象值。我想知道如何通过纯 JavaScript 或使用像 lodash 这样的辅助库来实现这一点。

我已经尝试过使用 lodash 的 _.groupBy 和 Array.prototype.reduce()，但还没有成功。数据如下:

{
  "2019-01-04": [
    {
        "payments": [
            {
                "sum": "12",
                "currency": "€"
            }
        ]
    }
  ],

  "2019-01-06": [
    {
        "payments": [
            {
                "sum": "50",
                "currency": "€"
            },
            {
                "sum": "30",
                "currency": "£"
            },
            {
                "sum": "40",
                "currency": "Lek"
            },
            {
                "sum": "2",
                "currency": "£"
            },
            {
                "sum": "60",
                "currency": "£"
            }
        ]
    }
  ]
}

我期望的结果是 sum 属性包含该日期以来相同类型的所有货币的总和:

{
  "2019-01-04": [
    {
        "payments": [
            {
                "sum": "12",
                "currency": "€"
            }
        ]
    }
  ],

  "2019-01-06": [
    {
        "payments": [
            {
                "sum": "50",
                "currency": "€"
            },
            {
                "sum": "92",
                "currency": "£"
            },
            {
                "sum": "40",
                "currency": "Lek"
            }
        ]
    }
  ]
}

Answer 1

const result = {};
Object.keys(input).forEach(date => {
    result[date] = [{ }];
    result[date][0].payments = input[date][0].payments.reduce((payments, c) => {
        const grp = payments.find(p => p.currency === c.currency);
        grp ? grp.sum = +grp.sum + +c.sum : payments.push(c);
        return payments;
    }, []);
});