1つの面接問題は深いコピーと再帰で実現されます(仮想domツリーに似ています)

実装方法:
再帰
深いコピーの3つの実装方法
1、JSON方法実現

//_tmp result      ，      ，        。
let deepClone = function (obj) {
    let _tmp = JSON.stringify(obj);//      json     
    let result = JSON.parse(_tmp);//              js  
    return result;
};

let obj1 = {
    weiqiujaun: {
        age: 20,
        class: 1502
    },
    liuxiaotian: {
        age: 21,
        class: 1501
    }
};

let test = deepClone(obj1);
console.log(test);

2、for...inで遍歴と複製を実現する

function deepClone(obj) {
    let result = typeof  obj.splice === "function" ? [] : {};
    if (obj && typeof obj === 'object') {
        for (let key in obj) {
            if (obj[key] && typeof obj[key] === 'object') {
                result[key] = deepClone(obj[key]);//         object   ，    deepClone,                      。
            } else {
                result[key] = obj[key];//          object   ，                          。
            }

        }
        return result;
    }
    return obj;
}

let testArray = ["a", "b", "c", "d"];
let testRes = deepClone(testArray);
console.log(testRes);
console.log(typeof testRes[1]);

let testObj = {
    name: "weiqiujuan",
    sex: "girl",
    age: 22,
    favorite: "play",
    family: {brother: "son", mother: "haha", father: "heihei"}
};
let testRes2 = deepClone(testObj);
testRes2.family.brother = "weibo";
console.log(testRes2);

3、配列を利用するArray.prototype.forEach進copy

let deepClone = function (obj) {
    let copy = Object.create(Object.getPrototypeOf(obj));
    let propNames = Object.getOwnPropertyNames(obj);
    propNames.forEach(function (items) {
        let item = Object.getOwnPropertyDescriptor(obj, items);
        Object.defineProperty(copy, items, item);

    });
    return copy;
};

let testObj = {
    name: "weiqiujuan",
    sex: "girl",
    age: 22,
    favorite: "play",
    family: {brother: "wei", mother: "haha", father: "heihei"}
}
let testRes2 = deepClone(testObj);
console.log(testRes2);

4、浅いコピー(object.assignメソッドを使用)

let target=[];
let testArr=[2,3,5,8];
Object.assign(target,testArr);
console.log(target);
testArr.push(8);
console.log("     "+target+",     "+testArr);