Skip to content

JavaScript, how to extend a class

How to extend a class in JavaScript

JavaScript inheritance works using classes.

Suppose you have a class Animal:

class Animal {
  breathe() {
    //...
  }
}

All animals breathe. I think. We can take this as a general rule for this example.

But not animals walk. Some animals can fly, etc.

So we can extend this class to form species, and we extend from the base class to inherit the breathe() method, and provide specific methods and properties:

class Fish extends Animal {
  swim() {
    //...
  }
}
class Bird extends Animal {
  fly() {
    //...
  }
}

You can instantiate an instance of a class using the new keyword, and you end up with an object:

const randomAnimal = new Animal()
const hummingbird = new Bird()

→ Here's my latest YouTube video

→ Get my JavaScript Beginner's Handbook

→ I wrote 17 books to help you become a better developer, download them all at $0 cost by joining my newsletter

JOIN MY CODING BOOTCAMP, an amazing cohort course that will be a huge step up in your coding career - covering React, Next.js - next edition February 2025

Bootcamp 2025

Join the waiting list