拷贝
浅拷贝 shallowClone
function shallowClone(obj) {
if (typeof obj !== 'object' || obj === null) {
return obj;
}
if (obj instanceof Date) {
return new Date(obj);
}
if (obj instanceof RegExp) {
return new RegExp(obj);
}
if (obj instanceof Set) {
let objClone = new Set();
obj.forEach(item => objClone.add(item));
return objClone;
}
if (obj instanceof Map) {
let objClone = new Map();
obj.forEach((value, key) => objClone.set(key, value));
return objClone;
}
const keys = Object.keys(obj);
let objClone = Array.isArray(obj) ? [] : {};
if (keys.length < 1) {
return objClone;
}
keys.forEach(key => (objClone[key] = obj[key]));
return objClone;
}
深拷贝 deepClone
判断数据类型 + 循环递归
function deepClone(obj, hash = new WeakMap()) {
// Primitive Type
if (typeof obj !== 'object' || obj === null) {
return obj;
}
// Date
if (obj instanceof Date) {
return new Date(obj);
}
//RegExp
if (obj instanceof RegExp) {
return new RegExp(obj);
}
// Set
if (obj instanceof Set) {
let objClone = new Set();
obj.forEach(item => objClone.add(deepClone(item)));
return objClone;
}
// Map
if (obj instanceof Map) {
let objClone = new Map();
obj.forEach((value, key) => objClone.set(deepClone(key), deepClone(value)));
return objClone;
}
// search hash map
if (hash.has(obj)) return hash.get(obj);
// Array Object
const keys = Object.keys(obj);
let objClone = Array.isArray(obj) ? [] : {};
if (keys.length < 1) {
return objClone;
}
// add key->value to hash
hash.set(obj, objClone);
keys.forEach(key => {
objClone[key] =
typeof obj[key] === 'object'
? deepClone(obj[key], hash)
: deepClone(obj[key]);
});
return objClone;
}
这里有个点大家要注意下，对于 function 类型，这里是直接赋值的，还是共享一个内存值。这是因为函数更多的是完成某些功能，有个输入值和返回值，而且对于上层业务而言更多的是完成业务功能，并不需要真正将函数深拷贝。
但是 function 类型要怎么拷贝呢？
javascript 深拷贝(deepClone) https://www.google.com/url?q=https://segmentfault.com/a/1190000006687581&sa=D&ust=1570449321569000