js 实现深拷贝

function deepClone(obj) {
  return JSON.parse(JSON.stringify(obj));
}

const original = { a: 1, b: { c: 2 } };
const clone = deepClone(original);
console.log(clone); // { a: 1, b: { c: 2 } }
console.log(clone === original); // false
console.log(clone.b === original.b); // false

function deepClone(obj, hash = new WeakMap()) {
  if (Object(obj) !== obj) return obj; // 基本类型直接返回
  if (hash.has(obj)) return hash.get(obj); // 处理循环引用
  let result = Array.isArray(obj) ? [] : {};
  hash.set(obj, result);
  Reflect.ownKeys(obj).forEach(key => {
    result[key] = deepClone(obj[key], hash);
  });
  return result;
}

const original = { a: 1, b: { c: 2 } };
const clone = deepClone(original);
console.log(clone); // { a: 1, b: { c: 2 } }
console.log(clone === original); // false
console.log(clone.b === original.b); // false

const _ = require('lodash');

const original = { a: 1, b: { c: 2 } };
const clone = _.cloneDeep(original);
console.log(clone); // { a: 1, b: { c: 2 } }
console.log(clone === original); // false
console.log(clone.b === original.b); // false