我如何将相同的对象值推入数组

Question

我这几天一直在尝试处理下面的json。

[
  {createdAt: "2021-09-09 07:37", user_id: "admin", type: "click", query: "spider"},
  {createdAt: "2021-09-09 07:37", user_id: "admin", type: "search", query: "spider"},
  {createdAt: "2021-09-09 07:38", user_id: "user", type: "click", query: "hi"},
]

如果某个值是重复的，我想将它添加到一个新数组中。像这样

[
  {
    createdAt: "2021-09-09 07:37", 
    user_id: "admin",
    query: "spider",
    type: "click",
    result: [
     {createdAt: "2021-09-09 07:37", user_id: "admin", type: "search", query: "spider"}
    ]
  },
  {createdAt: "2021-09-09 07:38", user_id: "user", type: "click", query: "hi"}
]

lodash的groupBy函数最相似，但是我对JavaScript不熟悉。
任何人都可以帮助我如何处理那些 json？

Answer 1

您可以使用Map 和forEach 轻松实现结果

const arr = [
  {
    createdAt: "2021-09-09 07:37",
    user_id: "admin",
    type: "click",
    query: "spider",
  },
  {
    createdAt: "2021-09-09 07:37",
    user_id: "admin",
    type: "search",
    query: "spider",
  },
  {
    createdAt: "2021-09-09 07:38",
    user_id: "user",
    type: "click",
    query: "hi",
  },
];

let map = new Map();

arr.forEach((obj) => {
  const { user_id, createdAt } = obj;
  if (map.has(`${user_id}|${createdAt}`))
    map.get(`${user_id}|${createdAt}`).push(obj);
  else map.set(`${user_id}|${createdAt}`, [obj]);
});

const result = [];
for (let [, v] of map) {
  const [first, ...rest] = v;
  const temp = Object.assign({}, first);
  if (rest.length) temp.result = rest;
  result.push(temp);
}

console.log(result);

/* This is not a part of answer. It is just to give the output fill height. So IGNORE IT */
.as-console-wrapper { max-height: 100% !important; top: 0; }

Answer 2

下面是另一种方法。

1. 使用一个Array.reduce构建一个字典来存储key出现的次数以及key的数据保存在哪里。

2. 使用另一个Array.reduce 循环所有元素，然后应用您的逻辑。

const data = [
  {createdAt: "2021-09-09 07:37", user_id: "admin", type: "click", query: "spider"},
  {createdAt: "2021-09-09 07:37", user_id: "admin", type: "search", query: "spider"},
  {createdAt: "2021-09-09 07:38", user_id: "user", type: "click", query: "hi"},
]

function relayout() {
  const indexes = data.reduce((pre, cur) => {
    pre[`${cur.createdAt}-${cur.user_id}`] = [0, 0] // count, position in result array
    return pre
  }, {})
  return data.reduce((pre, cur) => {
    const key = `${cur.createdAt}-${cur.user_id}`
    if (indexes[key][0] > 0) {
      pre[indexes[key][1]].result = [
        ...(pre[indexes[key][1]].result || []),
        cur
      ]
    } else {
      pre.push(cur)
      indexes[key][1] = pre.length - 1
    }
    indexes[key][0] += 1
    return pre
  }, [])
}

console.log(relayout(data))