ES6 - 基于两个键的不同元素[重复]答案

【问题标题】：ES6 - Distinct elements based on two keys [duplicate]ES6 - 基于两个键的不同元素[重复]
【发布时间】：2018-03-07 14:07:47
【问题描述】：

在下面的数组中，有重复的元素（具有相同的日期和ID）

[{date: "2018-02-20", id: "ccff5cae-0d38-450d-90f9-2490256db84c"},
{date: "2018-02-21", id: "8ffc7266-6a19-40a7-b181-7c7d73be8467"},
{date: "2018-02-22", id: "147afdd1-8c8b-4fde-b992-d8d8465a1771"},
{date: "2018-02-23", id: "72f10683-17a5-49d1-9e78-5fc2b380a314"},
{date: "2018-02-24", id: "2d2cd12c-2472-4e1d-96c9-84d8a0df1eda"},
{date: "2018-03-05", id: "5daf20a7-7106-419d-9761-3e96dfedf5ff"},
{date: "2018-03-08", id: "4bbcc474-ff88-4fc0-aede-abde0ae42b93"},
{date: "2018-03-08", id: "2a883953-df6a-45b1-9e0a-eb67cc1752b3"},
{date: "2018-03-08", id: "578b78cb-6d2c-4e91-a5a1-6d081945a51b"},
{date: "2018-03-09", id: "defb35e5-1a43-4347-ac4b-a85093551900"},
{date: "2018-02-20", id: "ccff5cae-0d38-450d-90f9-2490256db84c"},
{date: "2018-02-21", id: "8ffc7266-6a19-40a7-b181-7c7d73be8467"},
{date: "2018-02-22", id: "147afdd1-8c8b-4fde-b992-d8d8465a1771"},
{date: "2018-02-23", id: "72f10683-17a5-49d1-9e78-5fc2b380a314"},
{date: "2018-02-24", id: "2d2cd12c-2472-4e1d-96c9-84d8a0df1eda"},
{date: "2018-03-05", id: "5daf20a7-7106-419d-9761-3e96dfedf5ff"},
{date: "2018-03-08", id: "4bbcc474-ff88-4fc0-aede-abde0ae42b93"},
{date: "2018-03-08", id: "2a883953-df6a-45b1-9e0a-eb67cc1752b3"},
{date: "2018-03-08", id: "578b78cb-6d2c-4e91-a5a1-6d081945a51b"},
{date: "2018-03-09", id: "defb35e5-1a43-4347-ac4b-a85093551900"},]

（在 ES6 中）删除重复项的最佳方法是什么？

【问题讨论】：

标签： javascript ecmascript-6

【解决方案1】：

不完全是 ES6，但一种方法是使用 Lodash uniq 函数

_.uniq([2, 1, 2]);
// => [2, 1]

编辑：UniqBy 可能更符合您的要求：

// The `_.property` iteratee shorthand.
_.uniqBy([{ 'x': 1 }, { 'x': 2 }, { 'x': 1 }], 'x');
// => [{ 'x': 1 }, { 'x': 2 }]

【讨论】：

【解决方案2】：

您可以使用地图，并根据日期和 ID 制作唯一键..

下面是一个例子。

var data =
[{date: "2018-02-20", id: "ccff5cae-0d38-450d-90f9-2490256db84c"},
{date: "2018-02-21", id: "8ffc7266-6a19-40a7-b181-7c7d73be8467"},
{date: "2018-02-22", id: "147afdd1-8c8b-4fde-b992-d8d8465a1771"},
{date: "2018-02-23", id: "72f10683-17a5-49d1-9e78-5fc2b380a314"},
{date: "2018-02-24", id: "2d2cd12c-2472-4e1d-96c9-84d8a0df1eda"},
{date: "2018-03-05", id: "5daf20a7-7106-419d-9761-3e96dfedf5ff"},
{date: "2018-03-08", id: "4bbcc474-ff88-4fc0-aede-abde0ae42b93"},
{date: "2018-03-08", id: "2a883953-df6a-45b1-9e0a-eb67cc1752b3"},
{date: "2018-03-08", id: "578b78cb-6d2c-4e91-a5a1-6d081945a51b"},
{date: "2018-03-09", id: "defb35e5-1a43-4347-ac4b-a85093551900"},
{date: "2018-02-20", id: "ccff5cae-0d38-450d-90f9-2490256db84c"},
{date: "2018-02-21", id: "8ffc7266-6a19-40a7-b181-7c7d73be8467"},
{date: "2018-02-22", id: "147afdd1-8c8b-4fde-b992-d8d8465a1771"},
{date: "2018-02-23", id: "72f10683-17a5-49d1-9e78-5fc2b380a314"},
{date: "2018-02-24", id: "2d2cd12c-2472-4e1d-96c9-84d8a0df1eda"},
{date: "2018-03-05", id: "5daf20a7-7106-419d-9761-3e96dfedf5ff"},
{date: "2018-03-08", id: "4bbcc474-ff88-4fc0-aede-abde0ae42b93"},
{date: "2018-03-08", id: "2a883953-df6a-45b1-9e0a-eb67cc1752b3"},
{date: "2018-03-08", id: "578b78cb-6d2c-4e91-a5a1-6d081945a51b"},
{date: "2018-03-09", id: "defb35e5-1a43-4347-ac4b-a85093551900"}];

const d = Array.from(new Map(data.map((v) => {
  return [v.date + v.id, v];
})).values());

console.log(`Old length: ${data.length}`);
console.log(`New length: ${d.length}`);
console.log(d);

【讨论】：