SOURCE

// 原型继承
// 缺陷
//1：如果父类有引用类型（对象、数组、函数）的属性，其中一个实例修改了这个属性，所有的实例上的这个属性都会被修改。
//2：实例无法向其构造函数传递参数
const A = function () {
    function Animal() {
        this.species = '动物';
        this.friend = ['cow']
    }
    function Cat() {
        this.eat = 'fish'
    }
    Cat.prototype = new Animal();
    Cat.prototype.constructor = Cat;
    let smallCat = new Cat();
    let middleCat = new Cat();
    console.log(smallCat.species, middleCat.species);//动物
    smallCat.species = '猫咪';
    smallCat.friend.push('dog');
    console.log(smallCat.friend, middleCat.friend);
}
// Class继承
const B = function () {
    class Animal {
        constructor() {
            this.species = '动物';
            this.friend = ['cow']
        }
    }
    class Cat extends Animal {
        constructor() {
            super();
            this.eat = 'fish'
        }
    }
    let smallCat = new Cat();
    let middleCat = new Cat();
    smallCat.friend.push('dog');
    console.log(smallCat.friend, 'smallCat.friend');
    console.log(middleCat.friend, 'smallCat.friend')
}
B()