javascript - ES6 javascript继承

Question

提供以下代码:

class Person {
    constructor(name) {
        this.name = name;
    }
    sayHello() {
        console.log('Hello, my name is ' + this.name);
    }
    sayHelloAndBy() {
        this.sayHello();
        console.log('Bye');
    }

}
class Student extends Person {
    constructor(name, grade) {
        super(name);
        this.grade = grade;
    }
    sayHello() {
        console.log(`Hi, I'm a studend and my name is ` + this.name);
    }
}


let b = new Student("Some guy", 5);

b.sayHelloAndBy();

我想找出一种调用 sayHello 的方法，如 Person 中定义的那样，而不是在 Student 中定义。可能吗？

在 php 中有 self:: 允许这样做，但我不确定 JS 是否有类似的概念。

Answer 1

您可以通过 Person 的原型(prototype)属性引用 Person 中定义的 sayHello 版本，并使用必要的 调用它这使用Function#call :

sayHelloAndBye() {
    Person.prototype.sayHello.call(this);
    console.log('Bye');
}

可运行:

class Person {
    constructor(name) {
        this.name = name;
    }
    
    sayHello() {
        console.log('Hello, my name is ' + this.name);
    }
    
    sayHelloAndBye() {
        Person.prototype.sayHello.call(this);
        console.log('Bye');
    }
}

class Student extends Person {
    constructor(name, grade) {
        super(name);
        this.grade = grade;
    }
    sayHello() {
        console.log(`Hi, I'm a studend and my name is ` + this.name);
    }
}

let b = new Student("Some guy", 5);

b.sayHelloAndBye();