合并数组中具有相同ID的对象 [英] Merge objects with same id in array

问题描述

我想我有一个死的简单问题，但仍然没有找到解决方案.我有一个看起来像这样的数组:

I guess I have a dead simple problem but still didn't find a solution. I have an array which looks like this:

var originalArray = [{
  id: 1,
  elements: [1, 2]
},
{
  id: 1,
  elements: [3, 4]
},
{
  id: 5,
  elements: ['a', 'b']
},
{
  id: 5,
  elements: ['c', 'd']
}, {
  id: 27,
  elements: []
}]

我想将其修改为如下形式(通过id和join元素合并):

I'd like to modify it to look like this (merge by id and join elements):

newArray = [{
  id: 1,
  elements: [1, 2, 3, 4]
}, {
  id: 5,
  elements: ['a', 'b', 'c', 'd']
}, {
  id: 27,
  elements: []
}]

我已经尝试过多次，但仍然没有找到一种优雅的方法.

I already had multiple tries but still didn't find an elegant way of doing it.

推荐答案

您可以创建一个由ID键控的对象，并将具有相同ID的元素压入它们，然后转换回数组.这比遍历较大数组的每次迭代都更有效:

You can create an object keyed by ID and push elements with the same ID to them, then convert back to an array. This is more efficient than looping through on every iteration for larger arrays:

var originalArray = [{
  id: 1,
  elements: [1, 2]
},
{
  id: 1,
  elements: [3, 4]
},
{
  id: 5,
  elements: ['a', 'b']
},
{
  id: 5,
  elements: ['c', 'd']
}, {
  id: 27,
  elements: []
}];

const arrayHashmap = originalArray.reduce((obj, item) => {
  obj[item.id] ? obj[item.id].elements.push(...item.elements) : (obj[item.id] = { ...item });
  return obj;
}, {});

const mergedArray = Object.values(arrayHashmap);

console.log(mergedArray);

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