SOURCE

// 深拷贝
function cloneDeep(obj, map = new WeakMap()) {
    if (obj === null) return obj;

    if (obj instanceof Date) return new Date(obj);

    if (obj instanceof RegExp) return new RegExp(obj);

    if (typeof obj !== 'object') return obj;

    if (map.get(obj)) return map.get(obj);

    const cloneObj = new obj.constructor();

    map.set(obj, cloneObj)

    for (key in obj) {
        if (obj.hasOwnProperty(key)) {
            cloneObj[key] = cloneDeep(obj[key], map);
        }
    }

    return cloneObj;

}

const obj = {
    name: 'cc',
    arr: [1, 2, 3],
    getName() {
        console.log(this.name);
    }
}

const cloneObj = cloneDeep(obj)
cloneObj.arr.push(4)
cloneDeep.name = 'zz'

console.log(obj)
console.log(cloneObj)

obj.getName();
cloneObj.getName()

console.log(obj.getName === cloneObj.getName)