# 如何实现一个深拷贝 (cloneDeep)
更多描述
const obj = {
re: /hello/,
f () {},
date: new Date(),
map: new Map(),
list: [1, 2, 3],
a: 3,
b: 4
}
cloneDeep(obj)
Issue
欢迎在 Issue 中交流与讨论: Issue 203 (opens new window)
Author
/**
* 深拷贝关注点:
* 1. JavaScript内置对象的复制: Set、Map、Date、Regex等
* 2. 循环引用问题
* @param {*} object
* @returns
*/
function deepClone(source, memory) {
const isPrimitive = (value) => {
return /Number|Boolean|String|Null|Undefined|Symbol|Function/.test(Object.prototype.toString.call(value));
}
let result = null;
memory || (memory = new WeakMap());
// 原始数据类型及函数
if (isPrimitive(source)) {
console.log('current copy is primitive', source);
result = source;
}
// 数组
else if (Array.isArray(source)) {
result = source.map(value => deepClone(value, memory));
}
// 内置对象Date、Regex
else if (Object.prototype.toString.call(source) === '[object Date]') {
result = new Date(source);
}
else if (Object.prototype.toString.call(source) === '[object Regex]') {
result = new RegExp(source);
}
// 内置对象Set、Map
else if (Object.prototype.toString.call(source) === '[object Set]') {
result = new Set();
for (const value of source) {
result.add(deepClone(value, memory));
}
}
else if (Object.prototype.toString.call(source) === '[object Map]') {
result = new Map();
for (const [key, value] of source.entries()) {
result.set(key, deepClone(value, memory));
}
}
// 引用类型
else {
if (memory.has(source)) {
result = memory.get(source);
} else {
result = Object.create(null);
memory.set(source, result);
Object.keys(source).forEach(key => {
const value = source[key];
result[key] = deepClone(value, memory);
});
}
}
return result;
}