实例对象和原型对象 继承 组合继承

版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/jeekmary/article/details/82023647

    <script>
        //一,实例对象中的属性和原型对象中的属性相同的问题
        function Person(name, age,sex) {
            this.name= name;
            this.age= age;
            this.sex = sex;
        }
        /**JS是一门动态的语言,只要使用了对象点，就产生了属性，如果没有赋值就会为null*/
        Person.prototype.sex = "女";
        let per = new Person("lily", 25, "男");
        console.log(per.name);
        console.log(per.age);
        console.log(per.sex);
        /**
         * 实例对象访问属性，首先是从实例对象中找,找到了就直接用，找不到就通过原型对象来找。
         *1, 通过实例对象是不能改变原型对象中的属性中
         * 2,想要改变原型对象中的值，就通过原型对象.属性来改变
         */
        console.log("--------------------------------------------");
        //二，继承
        function People(name, age, sex) {
            this.name = name;
            this.age = age;
            this.sex = sex;
        }
        People.prototype.eat = function () {
            console.log("人吃东西")
        };
        People.prototype.sleep = function () {
            console.log("人在睡觉")
        };
        People.prototype.play = function () {
            console.log("人在玩")
        };

        function Student(score) {
            console.log("小明得了"+score+"分.....")
        }
        Student.prototype = new People("丽丽", 26, "女");
        Student.prototype.study=function () {
            console.log("学习很累很累的哦.");
        };
        Student.prototype.playgame = function () {
            console.log("小明喜欢玩游戏")
        };
        let stu = new Student(29);
        console.log(stu.sex);
        console.log(stu.name);
        console.log(stu.age);
        stu.study();
        stu.play();
        stu.sleep();
        stu.eat();
        // 继承案例
        function Animal(name, weight) {
            this.name = name;
            this.weight = weight;
        }
        Animal.prototype.eat = function () {
            console.log("天天吃东西,就是吃")
        };
        function Dog(color) {
            this.color = color;
        }
        Dog.prototype = new Animal("哮天犬", "50kg");
        Dog.prototype.bitePerson = function () {
            console.log("哼 往往咬死你")
        };
        //哈士奇
        function ErHa(sex) {
            this.sex = sex;
        }
        ErHa.prototype = new Dog("黑白色");
        ErHa.prototype.playHost = function () {
            console.log("能陪主人玩的很开心")
        };
        let erha = new ErHa("男");
        console.log(erha.name,erha.weight,erha.color);
        erha.playHost();
        //三 以上的这种继承是不能继承原型属性的，所以这里需要采用组合继承来实现相关的功能
        function Father(name, age, sex) {
            this.name = name;
            this.age = age;
            this.sex = sex;
        }
        Father.prototype.smoke = function () {
            console.log("长辈喜欢抽烟")
        };
        function Son(name, age, sex, study) {
            Father.call(this.name,age,sex);
            this.study = study;
        }
        Son.prototype = new Father();//这里不用写
        Son.prototype.eat = function () {
            console.log("吃东西")
        };
        let st = new Son("lili" , "男" ,25 , "学习");
        st.eat();
        st.smoke();

    </script>