js深度刻隆-clone.js

const mapTag = '[object Map]';
const setTag = '[object Set]';
const arrayTag = '[object Array]';
const objectTag = '[object Object]';
const argsTag = '[object Arguments]';

const boolTag = '[object Boolean]';
const dateTag = '[object Date]';
const numberTag = '[object Number]';
const stringTag = '[object String]';
const symbolTag = '[object Symbol]';
const errorTag = '[object Error]';
const regexpTag = '[object RegExp]';
const funcTag = '[object Function]';

const deepTag = [mapTag, setTag, arrayTag, objectTag, argsTag];

function forEach(array, iteratee) {
let index = -1;
const length = array.length;
while (++index < length) {
iteratee(array[index], index);
}
return array;
}

function isObject(target) {
const type = typeof target;
return target !== null && (type === 'object' || type === 'function');
}

function getType(target) {
return Object.prototype.toString.call(target);
}

function getInit(target) {
const Ctor = target.constructor;
return new Ctor();
}

function cloneSymbol(targe) {
return Object(Symbol.prototype.valueOf.call(targe));
}

function cloneReg(targe) {
const reFlags = /\w*$/;
const result = new targe.constructor(targe.source, reFlags.exec(targe));
result.lastIndex = targe.lastIndex;
return result;
}

function cloneFunction(func) {
const bodyReg = /(?<={)(.|\n)+(?=})/m;
const paramReg = /(?<=\().+(?=\)\s+{)/;
const funcString = func.toString();
if (func.prototype) {
const param = paramReg.exec(funcString);
const body = bodyReg.exec(funcString);
if (body) {
if (param) {
const paramArr = param[0].split(',');
return new Function(...paramArr, body[0]);
} else {
return new Function(body[0]);
}
} else {
return null;
}
} else {
return eval(funcString);
}
}

function cloneOtherType(targe, type) {
const Ctor = targe.constructor;
switch (type) {
case boolTag:
case numberTag:
case stringTag:
case errorTag:
case dateTag:
return new Ctor(targe);
case regexpTag:
return cloneReg(targe);
case symbolTag:
return cloneSymbol(targe);
case funcTag:
return cloneFunction(targe);
default:
return null;
}
}

function clone(target, map = new WeakMap()) {

// 克隆原始类型
if (!isObject(target)) {
return target;
}

// 初始化
const type = getType(target);
let cloneTarget;
if (deepTag.includes(type)) {
cloneTarget = getInit(target, type);
} else {
return cloneOtherType(target, type);
}

// 防止循环引用
if (map.get(target)) {
return map.get(target);
}
map.set(target, cloneTarget);

// 克隆set
if (type === setTag) {
target.forEach(value => {
cloneTarget.add(clone(value, map));
});
return cloneTarget;
}

// 克隆map
if (type === mapTag) {
target.forEach((value, key) => {
cloneTarget.set(key, clone(value, map));
});
return cloneTarget;
}

// 克隆对象和数组
const keys = type === arrayTag ? undefined : Object.keys(target);
forEach(keys || target, (value, key) => {
if (keys) {
key = value;
}
cloneTarget[key] = clone(target[key], map);
});

return cloneTarget;
}

export default clone;