26_JavaScript之继承性

在ES6继承方式有多种，但存在一些弊端，这里介绍ES6之前终极继承方式

    <script>
        function Person(myName, myAge) {
            this.name = myName;
            this.age = myAge;
        }

        Person.prototype.say = function() {
            console.log(this.name, this.age);
        }

        function Student(myName, myAge, myScore) {
            Person.call(this, myName, myAge); //在子类的构造函数中通过call借助父类的构造函数,这里的this指的是Student
            this.score = myScore;
            this.study = function() {
                console.log("day day up");
            }
        }

        Student.prototype = new Person(); //将子类的原型对象修改为父类的实例对象
        Student.prototype.constructor = Student;

        Student.prototype.run = function() {
            console.log("run");
        }

        let stu = new Student("ww", 19, 99);
        console.log(stu.score);
        stu.say();
        stu.study();
    </script>

控制台输出：

js中继承的终极方法

在子类的构造函数中通过call借助父类的构造函数
将子类的原型对象修改为父类的实例对象

从ES6开始，继承又是另外一种写法 关键词extends

    <script>
        class Person {
            constructor(myName, myAge) {
                this.name = myName;
                this.age = myAge;
                this.say = function() {
                    console.log("Hello World");

                }
            }
        }
        class Student extends Person {
            constructor(myName, myAge, myScore) {
                super(myName, myAge);
                this.score = myScore;
                this.study - function() {
                    console.log("day day up");

                }
            }
        }

        let p = new Student("Durant", 30, 100);
        console.log(p);
    </script>

控制台输出：