Learn Class Inheritance with extends | Inheritance and Encapsulation

Understanding how to build relationships between classes is a key part of mastering object-oriented programming in JavaScript. The extends keyword is central to this process. When you use extends, you create a new class (a subclass or child class) that inherits the properties and methods of another class (the parent or base class). This allows you to reuse and organize code efficiently, letting subclasses specialize or expand on the behavior defined in their parent classes.

For example, you might have a general Animal class that describes features common to all animals. Then, you can create a Dog class that extends Animal, automatically gaining all the abilities and properties of Animal while also adding features unique to dogs.


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class Animal {
  constructor(name) {
    this.name = name;
  }
  speak() {
    console.log(`${this.name} makes a sound.`);
  }
}

class Dog extends Animal {
  bark() {
    console.log(`${this.name} barks.`);
  }
}

const myDog = new Dog("Rex");
myDog.speak(); // Rex makes a sound.
myDog.bark(); // Rex barks.

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Section 2. Chapter 1

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              123456789101112131415161718
            
class Animal {
  constructor(name) {
    this.name = name;
  }
  speak() {
    console.log(`${this.name} makes a sound.`);
  }
}

class Dog extends Animal {
  bark() {
    console.log(`${this.name} barks.`);
  }
}

const myDog = new Dog("Rex");
myDog.speak(); // Rex makes a sound.
myDog.bark(); // Rex barks.

Everything was clear?

Thanks for your feedback!

Section 2. Chapter 1