大厂面试必须掌握的六种继承方式，你会吗？

// 1：原型链继承
function Father() {
    this.name = 'justin';
}
Father.prototype.getName = function () {
    return this.name
}
function Child() { }
Child.prototype = new Father();
const child = new Child();
console.log(child.getName());
复制代码

// 2：构造函数继承
function Father() {
    this.name = 'justin';
    this.say = {haha: 111}
}
function Child(age) {
    Father.call(this);
    this.age = age;
}
const child1 = new Child(10);
const child2 = new Child(20);
child1.say.haha = 222;
console.log(child1);
console.log(child2);
复制代码

// 3：组合继承（组合指的是组合了原型链继承和构造函数继承）
function Father(age) {
    this.colors = ['red','pink'];
    this.age = age;
}
Father.prototype.say = () => '你好';
function Child(name,age) {
    // 构造函数的方式
    Father.call(this,age);
    this.name = name;
} 
// 原型链
Child.prototype = new Father();
Child.prototype.constructor = Child;
const child1 = new Child('张三',20);
const child2 = new Child('李四',25);
Child.prototype
child1
child1.colors.push('black');
console.log(child1.colors);
console.log(child2.colors);
console.log(child1.say());
复制代码

// 4：原型式继承
function createObj(o) {
    function F() { };
    F.prototype = o;
    return new F();
}
const obj = {
    name: 'justin',
    friends: [1, 2, 3, 4]
}
// 方式1
const m1 = createObj(obj);
const m2 = createObj(obj);
// 方式2
const m3 = Object.create(obj);
console.log(m1.name);  //justin
console.log(m2.name);  //justin
m1.friends.push(666);
console.log(m1.friends);  // [1,2,3,4,666]
console.log(m2.friends);  // [1,2,3,4,666]
复制代码

// 5：寄生式继承
function objCopy(o) {
    function F() {};
    F.prototype = o;
    return new F();
}
function enhanceObj(o) {
    const clone = objCopy(o);
    clone.say = function() {
        return 'hi';
    }
    return clone;
}
const obj = {
    name: 'justin',
    colors: [1,2,3]
}
const m1 = enhanceObj(obj);
const m2 = enhanceObj(obj);
console.log(m1.name);  //justin
console.log(m1.colors); //[1,2,3]
console.log(m1.say());  //hi
m1.colors.push(777)
console.log(m2.colors); // [1,2,3,777]
复制代码

// 6：寄生组合式继承
function Father(name) {
    this.name = name;
    this.colors = [1,2,3];
}
Father.prototype.say = function() {
    return 'hi';
}
function Child(name,age) {
    Father.call(this,name);
    this.age = age;
}
function createObj(o) {
    function F() {}
    F.prototype = o;
    return new F();
}
function inheritPrototype(Child,Father) {
    // 先构造一个指向父类构造函数原型对象的对象
    const prototype = createObj(Father.prototype);
    // 让这个对象的构造函数指向Child
    prototype.constructor = Child;
    Child.prototype = prototype;
}
inheritPrototype(Child,Father);
const child1 = new Child('justin',666);
const child2 = new Child('心飞扬',777);
console.log(child1.colors); //[1,2,3]
console.log(child2.colors); //[1,2,3]
child1.colors.push(666);
console.log(child1.colors);  // [1,2,3,666]
console.log(child2.colors);  // [1,2,3]
复制代码