使用类型构造函数扩展类

function Animal(name) {
    this.name = name;
}

Animal.prototype.sayName = function() {
    console.log('My name is ' + this.name);
};

function Dog(name, breed) {
    Animal.call(this, name); // 调用父类构造函数
    this.breed = breed;
}

// 设置Dog的原型为Animal的实例，实现继承
Dog.prototype = Object.create(Animal.prototype);
Dog.prototype.constructor = Dog; // 修复constructor指向

Dog.prototype.sayBreed = function() {
    console.log('My breed is ' + this.breed);
};

var myDog = new Dog('Buddy', 'Golden Retriever');
myDog.sayName(); // My name is Buddy
myDog.sayBreed(); // My breed is Golden Retriever

class Animal {
    constructor(name) {
        this.name = name;
    }

    sayName() {
        console.log(`My name is ${this.name}`);
    }
}

class Dog extends Animal {
    constructor(name, breed) {
        super(name); // 调用父类构造函数
        this.breed = breed;
    }

    sayBreed() {
        console.log(`My breed is ${this.breed}`);
    }
}

const myDog = new Dog('Buddy', 'Golden Retriever');
myDog.sayName(); // My name is Buddy
myDog.sayBreed(); // My breed is Golden Retriever