一、实现浅拷贝

直接赋值

let obj = { a: 1, b: { x: 2 }, arr: [1, [2], 3]};let obj1 = objobj1.b.x = 20;console.log(obj1);// expected output: { a: 1, b: { x: 20 }, arr: [1, [2], 3]};console.log(obj);// expected output: { a: 1, b: { x: 20 }, arr: [1, [2], 3]};

Object.assign方法

let obj = { a: 1, b: { x: 2 }, arr: [1, [2], 3]};let obj1 = Object.assign(obj);obj1.b.x = 20;console.log(obj1);// expected output: { a: 1, b: { x: 20 }, arr: [1, [2], 3]};console.log(obj);// expected output: { a: 1, b: { x: 20 }, arr: [1, [2], 3]};

for···in循环

function lightCopy(obj) {  let copy = Array.isArray(obj) ? [] : {};  for (let i in obj) {    copy[i] = obj[i];  }  return copy;}let obj = { a: 1, b: { x: 2 }, arr: [1, [2], 3]};let obj1 = lightCopy(obj);obj1.b.x = 20;console.log(obj1);// expected output: { a: 1, b: { x: 20 }, arr: [1, [2], 3]};console.log(obj);// expected output: { a: 1, b: { x: 20 }, arr: [1, [2], 3]};

二、实现深拷贝

JSON.stringify方法

function deepCopy(obj) {  let copy = JSON.parse(JSON.stringify(obj))  return copy}let obj = { a: 1, b: { x: 2 }, arr: [1, [2], 3]};let obj1 = deepCopy(obj);obj1.b.x = 20;console.log(obj1);// expected output: { a: 1, b: { x: 20 }, arr: [1, [2], 3]};console.log(obj);// expected output: { a: 1, b: { x: 2 }, arr: [1, [2], 3]};

for···in循环加递归

function deepCopy(obj) {  let copy = obj instanceof Array ? [] : {};  for (let i in obj) {    if (obj.hasOwnProperty(i)) {      copy[i] = typeof obj[i] === "object" ? deepCopy(obj[i]) : obj[i];    }  }  return copy;}let obj = { a: 1, b: { x: 2 }, arr: [1, [2], 3]};let obj1 = deepCopy(obj);obj1.b.x = 20;console.log(obj1);// expected output: { a: 1, b: { x: 20 }, arr: [1, [2], 3]};console.log(obj);// expected output: { a: 1, b: { x: 2 }, arr: [1, [2], 3]};

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