以下是我根據(jù)題主的問題所寫的代碼。

let users = [
    { 'name': 'barney', 'active': 1 },
    { 'name': 'fred', 'active': 2 },
    { 'name': 'pebbles', 'active': 3 }
];
let usersaaa = [
    { 'name': 'fred', 'active': 6 },
    { 'name': 'pebbles', 'active': 3 }
];

for(let i = 0; i < users.length; i++) {
    // 可將 find 替換成 for 循環(huán)
    let userItem = usersaaa.find(function(item) {
        return users[i].name === item.name;
    });

    if(userItem) {
        users[i] = userItem;
    }
}

小白一個(gè)，大神的代碼太高大上，跟不上節(jié)奏，只能寫點(diǎn)基礎(chǔ)的找找存在感
for(let i = 0;i<users.length;i++){
for (let j = 0; j < usersaaa.length; j++) {

if (users[i]["name"] == usersaaa[j]["name"]){
    users[i]["active"] = usersaaa[j]["active"];
    break;
}

}
}
console.log(users)

const users1 = [
    { 'name': 'barney', 'active': 1 },
    { 'name': 'fred', 'active': 2 },
    { 'name': 'pebbles', 'active': 3 }
];
const users2 = [
    { 'name': 'fred', 'active': 6 },
    { 'name': 'pebbles', 'active': 3 }
];

// https://www.npmjs.com/package/normalizer
const normalizer = function normalizer (arr, key) {
    let entities = {}
    let result = arr.map(item => {
        entities[item[key]] = item
        return item[key]
    })
    return { entities, result }
}

const merge = key => (users1, users2) => {
    let nml1 = normalizer(users1, key)
    let nml2 = normalizer(users2, key)
    let result = nml1.result.concat(nml2.result.filter(k => !nml1.entities[k]))
    let entities = Object.assign(nml1.entities, nml2.entities)
    return result.map(k => entities[k])
}

console.log(merge('name')(users1, users2))

t = {i['name']: i['active'] for i in usersaaa}
for i in users:
    if i['name'] in t:
        i['active'] = t[i['name']]

看錯(cuò)了，以為是python的額。。。

t = new Map();
usersaaa.forEach((i)=>{t.set(i.name, i)})
for(var i = 0; i < users.length; i++) {
    if(t.has(users[i].name)){
        users[i] = t.get(users[i].name)
    }
}
console.log(users)

時(shí)間復(fù)雜度O(m+n), 二重循環(huán)時(shí)間復(fù)雜度O(mn)

users.map((item) => {
    usersaaa.forEach((citem) => {
        if (item.name == citem.name) {
            Object.assign(item, citem)
        }
    })
})

console.log(users)