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();

我想找出一种方法sayHello，而不是Person中定义的Student。有可能吗？

在php中有self::允许人们这样做，但我不确定JS是否有类似的概念。

Answer 1

您可以参考sayHello到Person的prototype属性中定义的Person版本，并使用Function#call使用必要的this进行调用：

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

可运行：

＆＃13;

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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();

＆＃13;

＆＃13;

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