如何在javascript中根据日期有条件地连接两个数组

Question

我有两个具有相同ID的用户数组。我想根据每个用户拥有的updatedAt属性合并它们。具有更新的updatedAt属性的用户具有优先级。

const users1 = [
{ id: 1, name: 'user1', childUsers: [2], updatedAt: '2022-02-23T00:00:00.000Z' },
{ id: 2, name: 'user2', childUsers: [3, 4], updatedAt: '2022-01-26T00:00:00.000Z' },
{ id: 3, name: 'user3', childUsers: [2, 3], updatedAt: '2022-02-24T00:00:00.000Z' },
{ id: 4, name: 'user4', childUsers: [2, 4], updatedAt: '2022-02-26T00:00:00.000Z' },
]

const users2 = [
{ id: 1, name: 'user1', childUsers: [2], updatedAt: '2022-02-26T00:00:00.000Z' },
{ id: 2, name: 'user2.1', childUsers: [3, 4], updatedAt: '2022-02-27T00:00:00.000Z' },
{ id: 3, name: 'user3', childUsers: [2, 3], updatedAt: '2022-02-26T00:00:00.000Z' },
{ id: 4, name: 'user4.1', childUsers: [2, 4], updatedAt: '2022-02-27T00:00:00.000Z' },
]

输出应为

const mergedUsers = [
{ id: 1, name: 'user1', childUsers: [2], updatedAt: '2022-02-26T00:00:00.000Z' },
{ id: 2, name: 'user2.1', childUsers: [3, 4], updatedAt: '2022-02-27T00:00:00.000Z' },
{ id: 3, name: 'user3', childUsers: [2, 3], updatedAt: '2022-02-26T00:00:00.000Z' },
{ id: 4, name: 'user4.1', childUsers: [2, 4], updatedAt: '2022-02-27T00:00:00.000Z' },

]

Answer 1

您可以使用Array.reduce()按id对用户进行分组，用更新的updatedAt属性替换任何条目。

一旦我们有了分组的用户，我们就可以使用Object.values()来获得所需的结果：

const users1 = [
{ id: 1, name: 'user1', childUsers: [2], updatedAt: '2022-02-23T00:00:00.000Z' },
{ id: 2, name: 'user2', childUsers: [3, 4], updatedAt: '2022-01-26T00:00:00.000Z' },
{ id: 3, name: 'user3', childUsers: [2, 3], updatedAt: '2022-02-24T00:00:00.000Z' },
{ id: 4, name: 'user4', childUsers: [2, 4], updatedAt: '2022-02-26T00:00:00.000Z' },
]
const users2 = [
{ id: 1, name: 'user1', childUsers: [2], updatedAt: '2022-02-26T00:00:00.000Z' },
{ id: 2, name: 'user2.1', childUsers: [3, 4], updatedAt: '2022-02-27T00:00:00.000Z' },
{ id: 3, name: 'user3', childUsers: [2, 3], updatedAt: '2022-02-26T00:00:00.000Z' },
{ id: 4, name: 'user4.1', childUsers: [2, 4], updatedAt: '2022-02-27T00:00:00.000Z' },
]
const result = Object.values([...users1, ...users2].reduce((acc, user) => { 
// Entry either does not exist or has an older updatedAt property
if (!acc[user.id] || (user.updatedAt > acc[user.id].updatedAt)) {
acc[user.id] = user;
}
return acc;
}, {}))
console.log('Result:', result)

Answer 2

您希望将第一个数组中的每个用户与其第二个数组中相似的用户进行比较，然后选择更新日期较高的用户。

const users1 = [...];
const users2 = [...];
const merged = users1.map((user1) => {
// loop through the users1 array 
const duplicateUser = users2.find((user2) => user1.id === user2.id);
// if a similar user was found
if (duplicateUser) {
// compare and return the user with the newer updatedAt date
return new Date(duplicateUser.updatedAt) > new Date(user1.updatedAt)
? duplicateUser
: user1;
}
return user1; // in the case of no duplicates 
});
console.log(merged);