(function () {
    class Animal {
        constructor(name) {
            this.name = name;
        }
        say() {
            console.log(`我是一只${this.name}`);
        }
    }
    /**
     * super 调用父类中要继承的属性
     * 若子类要添加新的属性
     * 子类的构造器要对弗雷德构造函数进行重写
     */
    class Cat extends Animal {
        constructor(name, age) {
            super(name);
            this.age = age;
        }
    }
    let cat1 = new Cat('小猫', 3);
    console.log(cat1);
    cat1.say();
})();