Inheritance Basics

Inheritance lets a class reuse behavior from a parent class and add its own details.

inheritance.ts

class Animal {
    name: string;

    constructor(name: string) {
        this.name = name;
    }

    label(): string {
        return this.name;
    }
}

class Dog extends Animal {
    breed: string;

    constructor(name: string, breed: string) {
        super(name);
        this.breed = breed;
    }

    summary(): string {
        return `${this.label()} is a ${this.breed}`;
    }
}

const dogName: string = ;
const dog: Dog = new Dog(dogName, "terrier");

console.log(dog.summary());

class Animal {
    name: string;

    constructor(name: string) {
        this.name = name;
    }

    label(): string {
        return this.name;
    }
}

class Dog extends Animal {
    breed: string;

    constructor(name: string, breed: string) {
        super(name);
        this.breed = breed;
    }

    summary(): string {
        return `${this.label()} is a ${this.breed}`;
    }
}

const dogName: string = ;
const dog: Dog = new Dog(dogName, "terrier");

console.log(dog.summary());

class Animal {
    name: string;

    constructor(name: string) {
        this.name = name;
    }

    label(): string {
        return this.name;
    }
}

class Dog extends Animal {
    breed: string;

    constructor(name: string, breed: string) {
        super(name);
        this.breed = breed;
    }

    summary(): string {
        return `${this.label()} is a ${this.breed}`;
    }
}

const dogName: string = ;
const dog: Dog = new Dog(dogName, "terrier");

console.log(dog.summary());

extends `extends` creates a child class that starts with the parent class behavior.