Abstract Classes In TypeScript

Abstract classes are like interfaces with superpowers. The keyword abstract makes sure, that you can not instantiate this class. But you can give some default implementations.

abstract class Animal {
  breathe (): void { //default implementation
    console.log('In and out, and in and out, ...');
  }

  abstract hunt (): void; // no specific implementation
}

class Dog extends Animal {
  hunt (): void {
    console.log('Woof, grrr, woof!');
  }
}

class Cat extends Animal {
  hunt (): void {
    console.log('...');
  }
}

class Horse extends Animal {
  hunt (): void {
    throw new Error('Where is my grass?');
  }
}

// Compiler error, because Animal is an abstract class
// const anonymous = new Animal();

const dark = new Horse();
dark.breathe();
dark.hunt();

export {}

Links

1. Interfaces in TypeScript
2. Creating classes that implement an interface in TypeScript