Javascript函数逻辑不工作

我正在尝试创建一个具有

通货

期初余额

期末余额

我有以下数据

var _ = require('underscore');

var accounts=[
    {
      "id":"20",
      "name":"OASIS MALL-RMB Account",
      "branchId":"6",
      "type_id":"1",
      "currency_id":"1",
      "balance":"0",
      "createdBy":"2",
      "active":"1",
      "ts":"2017-06-30 00:12:08"
    },
    {
      "id":"21",
      "name":"OASIS MALL-USD Account",
      "branchId":"6",
      "type_id":"1",
      "currency_id":"2",
      "balance":"0",
      "createdBy":"2",
      "active":"1",
      "ts":"2017-06-30 00:12:09"
    },
    {
      "id":"22","name":"OASIS MALL-DIRHAM Account",
      "branchId":"6",
      "type_id":"1",
      "currency_id":"3",
      "balance":"0",
      "createdBy":"2",
      "active":"1",
      "ts":"2017-06-30 00:12:09"
    },
    {
      "id":"23",
      "name":"OASIS MALL-UGX Account",
      "branchId":"6",
      "type_id":"1",
      "currency_id":"4",
      "balance":"0",
      "createdBy":"2",
      "active":"1",
      "ts":"2017-06-30 00:12:09"
    },
    {
      "id":"24",
      "name":"OASIS MALL-KSH Account",
      "branchId":"6",
      "type_id":"1",
      "currency_id":"5",
      "balance":"0",
      "createdBy":"2",
      "active":"1",
      "ts":"2017-06-30 00:12:09"
    }
]

var balances =[
  {
    "id":"101",
    "branchId":"6",
    "accountId":"20",
    "openingBalance":"3260000",
    "closingBalance":"3260000",
    "date":"2017-08-15",
    "ts":"2017-08-15 02:27:08"
  },
  {
    "id":"102",
    "branchId":"6",
    "accountId":"21",
    "openingBalance":"1882492",
    "closingBalance":"1882492",
    "date":"2017-08-15",
    "ts":"2017-08-15 02:27:08"
  },
  {
    "id":"103","branchId":"6",
    "accountId":"22",
    "openingBalance":"-3000",
    "closingBalance":"-3000",
    "date":"2017-08-15",
    "ts":"2017-08-15 02:27:08"
  },
  {
    "id":"104",
    "branchId":"6",
    "accountId":"23",
    "openingBalance":"95199318",
    "closingBalance":"95199318",
    "date":"2017-08-15",
    "ts":"2017-08-15 02:27:08"
  },
  {
    "id":"105",
    "branchId":"6",
    "accountId":"24",
    "openingBalance":"1847000",
    "closingBalance":"1847000",
    "date":"2017-08-15",
    "ts":"2017-08-15 02:27:08"
  }
]

我知道如何在循环和if语句中执行。但我想用功能性的方式来做 我试过写这段代码

var DisplayAccounts = function(accounts,balances){

  var displayaccounts = _(accounts).map((x)=>{


      var mybalance = _(balances)
      .reduce((acc,z)=>{
         acc={
           currency :x.currency_id,
           openingBalance : z.openingBalance,
           closingBalance : z.closingBalance
         };
         return acc;
      },{});
     return mybalance;

  });
  return  displayaccounts;
}

console.log(DisplayAccounts(accounts,balances));

但它给了我一个我不喜欢的答案。 它给了我

[ { currency: '1',
    openingBalance: '1847000',
    closingBalance: '1847000' },
  { currency: '2',
    openingBalance: '1847000',
    closingBalance: '1847000' },
  { currency: '3',
    openingBalance: '1847000',
    closingBalance: '1847000' },
  { currency: '4',
    openingBalance: '1847000',
    closingBalance: '1847000' },
  { currency: '5',
    openingBalance: '1847000',
    closingBalance: '1847000' } ]

相同的期初和期末余额。我需要每种货币都有相应的期初和期末余额，如下所示

[ { currency: '1',
    openingBalance: '3260000',
    closingBalance: '3260000' },
  { currency: '2',
    openingBalance: '1882492',
    closingBalance: '1882492' },
  { currency: '3',
    openingBalance: '-3000',
    closingBalance: '-3000' },
  { currency: '4',
    openingBalance: '95199318',
    closingBalance: '95199318' },
  { currency: '5',
    openingBalance: '1847000',
    closingBalance: '1847000' } ]

---

它是如何做到这一点的？

这不是一种纯粹的功能性方法，而是产生所需的结果：

function displayAccounts(acc, bal) {
    return acc.map(x => {
        let b = bal.find(b => b.accountId === x.id);
        return {
            currency: x.currency_id,
            openingBalance: b.openingBalance,
            closingBalance: b.closingBalance
        }
    });
}

console.log(displayAccounts(accounts, balances));

---

非常感谢。如果有人给了我一个纯功能性的答案，我会给它打分并接受它，但是等待@DevDig，这对我来说似乎是一个纯功能。“你能告诉我为什么它不是纯的吗？”HenryBbosa，因为函数式编程是一个范例，有些人可能认为这是实用的。然而，一些纯粹主义者可能将函数编程定义为“组成纯函数”，因此accounts map函数（b变量）中不会有“状态”。