Object.assign 与对象扩展运算符 [重复]答案

【问题标题】：Object.assign vs object spread operator [duplicate]Object.assign 与对象扩展运算符 [重复]
【发布时间】：2021-01-17 23:33:30
【问题描述】：

我总是不确定是否应该使用 Object.assign

const options = Object.assign({}, defaultOptions, localOptions);

或对象扩展运算符

const options = {...defaultOptions, ...localOptions};

何时考虑性能影响？

【问题讨论】：

我会说检查 jsperf jsperf.com/object-assign-vs-object-spread-2 但最近似乎总是下降。
我会说总是使用扩展运算符。它更新更干净。即使存在性能差异，大多数时候干净的代码是可取的。
当想要变异一个对象时，assign很有帮助

标签： javascript

【解决方案1】：

TLDR：对于小物体，我认为它们的性能相似

我用 jest 做了一些小测试。

这些都是我的代码示例来自JSON Data set example

// example 4
const optionsA = {
    "id": "0001",
    "type": "donut",
    "name": "Cake",
    "ppu": 0.55,
    "batters":
        {
            "batter":
                [
                    { "id": "1001", "type": "Regular" },
                    { "id": "1002", "type": "Chocolate" },
                    { "id": "1003", "type": "Blueberry" },
                    { "id": "1004", "type": "Devil's Food" }
                ]
        },
    "topping":
        [
            { "id": "5001", "type": "None" },
            { "id": "5002", "type": "Glazed" },
            { "id": "5005", "type": "Sugar" },
            { "id": "5007", "type": "Powdered Sugar" },
            { "id": "5006", "type": "Chocolate with Sprinkles" },
            { "id": "5003", "type": "Chocolate" },
            { "id": "5004", "type": "Maple" }
        ]
}

// example 8
const optionsB = {
    "items":
        {
            "item":
                [
                    {
                        "id": "0001",
                        "type": "donut",
                        "name": "Cake",
                        "ppu": 0.55,
                        "batters":
                            {
                                "batter":
                                    [
                                        { "id": "1001", "type": "Regular" },
                                        { "id": "1002", "type": "Chocolate" },
                                        { "id": "1003", "type": "Blueberry" },
                                        { "id": "1004", "type": "Devil's Food" }
                                    ]
                            },
                        "topping":
                            [
                                { "id": "5001", "type": "None" },
                                { "id": "5002", "type": "Glazed" },
                                { "id": "5005", "type": "Sugar" },
                                { "id": "5007", "type": "Powdered Sugar" },
                                { "id": "5006", "type": "Chocolate with Sprinkles" },
                                { "id": "5003", "type": "Chocolate" },
                                { "id": "5004", "type": "Maple" }
                            ]
                    }

                ]
        }
}

module.exports = {optionsA, optionsB}

这是Assign.test.js

const { optionsA, optionsB } = require("./Options");

test('jest assign test', () => {
  let options = Object.assign({}, optionsA,optionsB);
  expect(options).toEqual({
    "id": "0001",
    "type": "donut",
    "name": "Cake",
    "ppu": 0.55,
    "batters":
        {
            "batter":
                [
                    { "id": "1001", "type": "Regular" },
                    { "id": "1002", "type": "Chocolate" },
                    { "id": "1003", "type": "Blueberry" },
                    { "id": "1004", "type": "Devil's Food" }
                ]
        },
    "topping":
        [
            { "id": "5001", "type": "None" },
            { "id": "5002", "type": "Glazed" },
            { "id": "5005", "type": "Sugar" },
            { "id": "5007", "type": "Powdered Sugar" },
            { "id": "5006", "type": "Chocolate with Sprinkles" },
            { "id": "5003", "type": "Chocolate" },
            { "id": "5004", "type": "Maple" }
    ],
    "items":
        {
            "item":
                [
                    {
                        "id": "0001",
                        "type": "donut",
                        "name": "Cake",
                        "ppu": 0.55,
                        "batters":
                            {
                                "batter":
                                    [
                                        { "id": "1001", "type": "Regular" },
                                        { "id": "1002", "type": "Chocolate" },
                                        { "id": "1003", "type": "Blueberry" },
                                        { "id": "1004", "type": "Devil's Food" }
                                    ]
                            },
                        "topping":
                            [
                                { "id": "5001", "type": "None" },
                                { "id": "5002", "type": "Glazed" },
                                { "id": "5005", "type": "Sugar" },
                                { "id": "5007", "type": "Powdered Sugar" },
                                { "id": "5006", "type": "Chocolate with Sprinkles" },
                                { "id": "5003", "type": "Chocolate" },
                                { "id": "5004", "type": "Maple" }
                            ]
                    }

                ]
        }
  })
})

这是Spread.test.js

const { optionsA, optionsB } = require("./Options");

test('jest spread test', () => {
  let options = {...optionsA,...optionsB};
  expect(options).toEqual({
    "id": "0001",
    "type": "donut",
    "name": "Cake",
    "ppu": 0.55,
    "batters":
        {
            "batter":
                [
                    { "id": "1001", "type": "Regular" },
                    { "id": "1002", "type": "Chocolate" },
                    { "id": "1003", "type": "Blueberry" },
                    { "id": "1004", "type": "Devil's Food" }
                ]
        },
    "topping":
        [
            { "id": "5001", "type": "None" },
            { "id": "5002", "type": "Glazed" },
            { "id": "5005", "type": "Sugar" },
            { "id": "5007", "type": "Powdered Sugar" },
            { "id": "5006", "type": "Chocolate with Sprinkles" },
            { "id": "5003", "type": "Chocolate" },
            { "id": "5004", "type": "Maple" }
    ],
    "items":
        {
            "item":
                [
                    {
                        "id": "0001",
                        "type": "donut",
                        "name": "Cake",
                        "ppu": 0.55,
                        "batters":
                            {
                                "batter":
                                    [
                                        { "id": "1001", "type": "Regular" },
                                        { "id": "1002", "type": "Chocolate" },
                                        { "id": "1003", "type": "Blueberry" },
                                        { "id": "1004", "type": "Devil's Food" }
                                    ]
                            },
                        "topping":
                            [
                                { "id": "5001", "type": "None" },
                                { "id": "5002", "type": "Glazed" },
                                { "id": "5005", "type": "Sugar" },
                                { "id": "5007", "type": "Powdered Sugar" },
                                { "id": "5006", "type": "Chocolate with Sprinkles" },
                                { "id": "5003", "type": "Chocolate" },
                                { "id": "5004", "type": "Maple" }
                            ]
                    }

                ]
        }
  })
})

当我做这些测试时，他们有相似的时间做这项工作：

【讨论】：