JavaScript - 复制对象数组并在不修改原始数组的情况下进行更改

Question

我有一个对象数组.我想深度复制对象数组并对每个对象进行一些更改.我想这样做而不修改原始数组或该数组中的原始对象.

这就是我做的方式.但是,作为JavaScript的新手,我想确保这是一个很好的方法.

有一个更好的方法吗？

const users = 
[
    {
        id       : 1,    
        name     : 'Jack',
        approved : false
    },
    {
        id       : 2,    
        name     : 'Bill',
        approved : true
    },
    {
        id       : 3,    
        name     : 'Rick',
        approved : false
    },
    {
        id       : 4,    
        name     : 'Rick',
        approved : true
    }
];


const users2 = 
    users
        .map(
            (u) => 
            {
                return Object.assign({}, u);
            }
        )    
        .map(
            (u) => 
            {
                u.approved = true;
                return u;
            }
        );    


console.log('New users2 array of objects:')
console.log(users2);

console.log('This was original users array is untouched:')
console.log(users);

输出:

New users2 array of objects:
[ { id: 1, name: 'Jack', approved: true },
  { id: 2, name: 'Bill', approved: true },
  { id: 3, name: 'Rick', approved: true },
  { id: 4, name: 'Rick', approved: true } ]
This was original users array is untouched:
[ { id: 1, name: 'Jack', approved: false },
  { id: 2, name: 'Bill', approved: true },
  { id: 3, name: 'Rick', approved: false },
  { id: 4, name: 'Rick', approved: true } ]

Answer 1

对于单次传递,您也可以使用Object.assign已更改的属性.

const users = [{ id: 1, name: 'Jack', approved: false }, { id: 2, name: 'Bill', approved: true }, { id: 3, name: 'Rick', approved: false }, { id: 4, name: 'Rick', approved: true }];
const users2 = users.map(u => Object.assign({}, u, { approved: true }));

console.log(users2);
console.log(users);

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Answer 2

我更喜欢 JSON.stringify 和 JSON.parse

var users = [ { id: 1, name: 'Jack', approved: false },
{ id: 2, name: 'Bill', approved: true },
{ id: 3, name: 'Rick', approved: false },
{ id: 4, name: 'Rick', approved: true } ];

// user2 will be copy of array users without reference
var users2 = JSON.parse(JSON.stringify(users));

Answer 3

是的，看起来不错。您也可以在克隆时执行修改，以避免两次映射数组。

const users2 = users.map((u) => {
    const copiedUser = Object.assign({}, u);
    copiedUser.approved = true;
    return copiedUser;
});