ES6 减少数组中的嵌套对象

Question

我一直在使用 map 和 reduce 来处理一些迄今为止运行良好的对象和数组，但是我在使用一个数组时遇到了问题。

这里的数据示例：

var arr =
[
[
{
  "id": 6501511,
  "invoiceId": {
    "id": 1043773
  },
  "chargeBandType": "TIME",
  "jobTaskId": {
    "id": 19399852
  },
  "invoicedNet": {
    "amountString": 0,
    "currencyType": "USD"
  },
  "invoicedTaxOneOtherCurrency": null,
  "invoicedTaxOne": {
    "amountString": 0,
    "currencyType": "USD"
  },
  "taxOneRate": 0.1
},
{
  "id": 6501517,
  "invoiceId": {
    "id": 1043773
  },
  "chargeBandType": "TIME",
  "jobTaskId": null,
  "jobExpenseId": null,
  "jobThirdPartyCostId": {
    "id": 20602
  },
  "invoicedNet": {
    "amountString": 0,
    "currencyType": "USD"
  },
  "invoicedTaxOneOtherCurrency": null,
  "invoicedTaxOne": {
    "amountString": 0,
    "currencyType": "USD"
  },
  "taxOneRate": 0.1
},
{
  "id": 6501508,
  "invoiceId": {
    "id": 13773
  },
  "chargeBandType": "TIME",
  "jobTaskId": {
    "id": 19398574
  },
  "invoicedNet": {
    "amountString": 30,
    "currencyType": "USD"
  },
  "invoicedTaxOneOtherCurrency": null,
  "invoicedTaxOne": {
    "amountString": 3,
    "currencyType": "USD"
  },
  "taxOneRate": 0.1
},
{
  "id": 65014,
  "invoiceId": {
    "id": 104
  },
  "chargeBandType": "TIME",
  "jobTaskId": null,
  "jobExpenseId": null,
  "jobThirdPartyCostId": {
    "id": 206
  },
  "invoicedNet": {
    "amountString": 0,
    "currencyType": "USD"
  },
  "invoicedTaxOneOtherCurrency": null,
  "invoicedTaxOne": {
    "amountString": 0,
    "currencyType": "USD"
  },
  "taxOneRate": 0.1
}],
[
{
  "id": 6483,
  "invoiceId": {
    "id": 1042400
  },
  "chargeBandType": "TIME",
  "jobTaskId": {
    "id": 198574
  },
  "invoicedNet": {
    "amountString": 100,
    "currencyType": "USD"
  },
  "invoicedTaxOneOtherCurrency": null,
  "invoicedTaxOne": {
    "amountString": 10,
    "currencyType": "USD"
  },
  "taxOneRate": 0.1
}
]
];

我正在尝试减少 invoicedNet.amountString 的值，在上述情况下，这将带来 130 的总和。

我尝试了很多方法来解决这个问题，包括类似于以下的功能：

var sum = arr.reduce(function(a, b) {
return a += b.invoicedNet.amountString;
}, 0);

但是，无论我如何尝试，我都会收到错误消息：

TypeError: Cannot read property 'amountString' of undefined

（虽然它似乎将 b.invoicedNet 作为一个对象）。

有人可以建议一种方法吗？

谢谢！

Answer 1

您需要循环两个数组。

var arr = [[{ id: 6501511, invoiceId: { id: 1043773 }, chargeBandType: "TIME", jobTaskId: { id: 19399852 }, invoicedNet: { amountString: 0, currencyType: "USD" }, invoicedTaxOneOtherCurrency: null, invoicedTaxOne: { amountString: 0, currencyType: "USD" }, taxOneRate: 0.1 }, { id: 6501517, invoiceId: { id: 1043773 }, chargeBandType: "TIME", jobTaskId: null, jobExpenseId: null, jobThirdPartyCostId: { id: 20602 }, invoicedNet: { amountString: 0, currencyType: "USD" }, invoicedTaxOneOtherCurrency: null, invoicedTaxOne: { amountString: 0, currencyType: "USD" }, taxOneRate: 0.1 }, { id: 6501508, invoiceId: { id: 13773 }, chargeBandType: "TIME", jobTaskId: { id: 19398574 }, invoicedNet: { amountString: 30, currencyType: "USD" }, invoicedTaxOneOtherCurrency: null, invoicedTaxOne: { amountString: 3, currencyType: "USD" }, taxOneRate: 0.1 }, { id: 65014, invoiceId: { id: 104 }, chargeBandType: "TIME", jobTaskId: null, jobExpenseId: null, jobThirdPartyCostId: { id: 206 }, invoicedNet: { amountString: 0, currencyType: "USD" }, invoicedTaxOneOtherCurrency: null, invoicedTaxOne: { amountString: 0, currencyType: "USD" }, taxOneRate: 0.1 }], [{ id: 6483, invoiceId: { id: 1042400 }, chargeBandType: "TIME", jobTaskId: { id: 198574 }, invoicedNet: { amountString: 100, currencyType: "USD" }, invoicedTaxOneOtherCurrency: null, invoicedTaxOne: { amountString: 10, currencyType: "USD" }, taxOneRate: 0.1 }]],
    sum = arr.reduce(function (a, b) {
        b.forEach(function (c) {
            a += c.invoicedNet.amountString;
        });
        return a;
    }, 0);

console.log(sum);