JavaScript Class extends Keyword

Definition and Usage

extends Keywords are used to create a subclass (parent) of another class.

The subclass inherits all methods of another class.

Inheritance is very useful for code reusability: when creating a new class, reuse the properties and methods of the existing class.

Note:From the above example, you can see that,super() This method refers to the parent class. By calling super() Methods, we will call the parent class's constructor and can access the properties and methods of the parent class.

Instance

Create a class named "Model" that will inherit the methods of the "Car" class:

class Car {
  constructor(brand) {
    this.carname = brand;
  }
  present() {
    return 'I have a ' + this.carname;
  }
}
class Model extends Car {
  constructor(brand, mod) {
    super(brand);
    this.model = mod;
  }
  show() {
    return this.present() + ', it is a ' + this.model;
  }
}
mycar = new Model("Ford", "Mustang");
document.getElementById("demo").innerHTML = mycar.show();

Try It Yourself

Syntax

class childClass extends parentClass

Technical Details

JavaScript Version: ECMAScript 2015 (ES6)

Browser Support

Keywords Chrome IE Firefox Safari Opera
extends 49.0 13.0 45.0 9.0 36.0

Related pages

JavaScript Tutorial:Classe do JavaScript

JavaScript Tutorial:JavaScript ES6 (EcmaScript 2015)

Manual de referência do JavaScript:Palavra-chave super

Manual de referência do JavaScript:Método constructor()