//父类
        class Person {
            constructor(name, age) {
                this.name = name
                this.age = age
            }

            printInfo() {
                console.log(this.name)
                console.log(this.age)
            }
        }

        //字类
        class Student extends Person {
            constructor(name, age, major) {
                // this.name = name
                // this.age = age

                //调用父类的构造函数
                super(name, age)
                this.major = major
            }
            //定义在字类自身的原型对象上
            study() {
                console.log("好好学习")
            }

            //定义在字类自身的原型对象上
            //方法的覆盖、重写
            printInfo() {
                // console.log(this.name)
                // console.log(this.age)
                
                //调用父类的printInfo
                super.printInfo()
                console.log(this.major)
            }

        }

        let s1 = new Student("tom", 18, "IT")
        console.log(s1.name, s1.age, s1.major)
        //调用父类的继承来的方法
        s1.printInfo()
        //调用字类自身的方法
        s1.study()

        console.log(s1)