Javascript类扩展了子类功能

Question

如何在javascript ES6中调用子类中的父类函数？

Answer 1

在子类构造函数中调用super()以访问ES6中的父方法。

class Parent{
  constructor(){}
  sayHello(){ // <--------access this method from Parent class.
     console.log('Hello!');
  }
}

class Child extends Parent{ // <-----extend the Parent class
   constructor(){ 
     super(); // <-----you have to call the "super();" here in constructor
   } 
   alertit(){
      super.sayHello(); // <----now here parent class methods can be accessed here
  }
}

var c = new Child();

c.alertit(); // <----will log Hello!

Demo

Answer 2

关于super关键字的MDN文章中明确提到了这一点。

super([arguments]); // calls the parent constructor.
super.functionOnParent([arguments]);