ES6 按字段类型分组数组对象答案

【问题标题】：ES6 group array objects by field typeES6 按字段类型分组数组对象
【发布时间】：2018-09-09 13:15:38
【问题描述】：

是否有一种简洁的 es6 函数式方法可以按类型对项目进行分组，因为它是不可变的？

accounts.json

   [
         {"account": {"name": "Bob's credit", "type": "credit", "id": "1"}},
         {"account": {"name": "savings", "type": "savings", "id": "2"}},
         {"account": {"name": "vacation savings", "type": "savings", "id": "3"}},
         {"account": {"name": "son's savings", "type": "savings", "id": "4"},
         {"account": {"name": "wife's credit card", "type": "savings", "id": "5"}
   ]

预期

[
{"savings": [
    {"account": {"name": "savings", "type": "savings", "id": "2"}},
    {"account": {"name": "vacation savings", "type": "savings", "id": "3"}},
    {"account": {"name": "son's savings", "type": "savings", "id": "4"}
]},

{"checking": [
   {"account": {"name": "wife's credit card", "type": "savings", "id": "5"}
]

【问题讨论】：

请分享您的尝试。
es6没有内置函数来实现，需要自己过滤数组或者使用第三方库如lodash。

标签： javascript collections ecmascript-6

【解决方案1】：

您可以使用Array#reduce 将列表按其内部type 属性的元素分组：

const data = [
     {"account": {"name": "Bob's credit", "type": "credit", "id": "1"}},
     {"account": {"name": "savings", "type": "savings", "id": "2"}},
     {"account": {"name": "vacation savings", "type": "savings", "id": "3"}},
     {"account": {"name": "son's savings", "type": "savings", "id": "4"}},
     {"account": {"name": "wife's credit card", "type": "savings", "id": "5"}}
];

const res = data.reduce((acc, curr) => {
  if(!acc[curr.account.type]) acc[curr.account.type] = []; //If this type wasn't previously stored
  acc[curr.account.type].push(curr);
  return acc;
},{});

console.log(res);

【讨论】：