js 深拷贝和浅拷贝

/*

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## 深拷贝 => 复制体改变, 原体不改变 => 只保存在栈内存上

## 包含的数据类型 : Number String Boolean NULL undefined Symbol

let a = 100;

let aCopy = a;

aCopy = 200;

console.log(a);

    打印结果 :

    100

console.log(aCopy);

    打印结果 :

    200

======================================

let ccc = { name: "zhansan", age: 11 }

let b = ccc.name;

b = "zhaoliu";

let k = ccc.age;

k = 100;

console.log(ccc);

    打印结果:

    {

        age: 11,

        name: "张三",

    }


======================================

let newArr = [{ name: "zhangsan", age: 18 }, { name: "lisi", age: 20 }]

let y = newArr[0].name;

y = "wangwu";

console.log(newArr);

    打印结果:

    [

        {

            age: 18,

            name: "zhangsan",

        },

        {

            age: 20,

            name: "lisi",

        }

    ]

---------------------------------------------------------------------

## 浅拷贝 => 复制体改变, 原体改变 => 保存在堆内存,通过地址引用

## 包含的数据类型 : Function Array Object Date Math RegExp


let newObj = { name: "张三", age: 18 };

let newObjCopy = newObj;

newObjCopy.name = "李四";

newObjCopy.age = 26;

console.log(newObj);

    打印结果 :

    {

        age:26,

        name:"李四",

    }

console.log(newObjCopy);

    打印结果 :

    {

        age:26,

        name:"李四",

    }

======================================

let newArr = [{ name: "zhangsan", age: 18 }, { name: "lisi", age: 20 }]

let y = newArr[0];

y.name = "wangwu";

console.log(newArr);

    打印结果:

    [

        {

            age: 18,

            name: "wangwu",

        },

        {

            age: 20,

            name: "lisi",

        }

    ]

---------------------------------------------------------------------

## 浅拷贝 变成 深拷贝的方法

方法1 : JSON.parse(JSON.stringify())

## 缺陷:

        1. 函数无法拷贝

        2. 正则无法拷贝

        3. undefuned 无法拷贝

## 优点:

        1. 二级以后的也会被拷贝

let newObj = { name: "张三", age: 18 };

let newObjCopy2 = JSON.parse(JSON.stringify(newObj))

newObjCopy2.name = "王五";

newObjCopy2.age = 30;

console.log(newObj);

    打印结果 :

    {

        age:18,

        name:"张三",

    }

console.log(newObjCopy2);

    打印结果 :

    {

        age:30,

        name:"王五",

    }

========================================

方法2: Object.assign(target, source)

## 缺陷:

        1. 二级以后的不会被拷贝

## 优点:

        1. 函数可以拷贝

        2. 正则可以拷贝

        3. undefuned 可以拷贝

let newObj = {

    name: "张三",

    age: 18,

    say() {

        console.log("hello world !");

    },

    reg: /d/,

    data: undefined,

};

let newObjCopy2 = {};

Object.assign(newObjCopy2, newObj)

newObjCopy2.name = "王五";

newObjCopy2.age = 30;

console.log(newObj);

打印结果:

{

    name: "张三",

    age: 18,

    say() {

        console.log("hello world !");

    },

    reg: /d/,

    data: undefined,

}

---------------------------------------------------------------------

*/


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