What is inheritance?

Inheritance means one class can reuse and extend another class. The new class inherits properties and methods from the old one.

Example 1 — Basic inheritance

JavaScript Example:

class Animal {
  speak() {
    console.log("Some sound");
  }
}

class Dog extends Animal {
  bark() {
    console.log("Woof!");
  }
}

const d = new Dog();
d.speak(); // "Some sound" (inherited)
d.bark();  // "Woof!"      (its own method)

• Dog extends Animal ? gets all of Animal’s methods for free.
• You can also add new ones (like bark()).

Example 2 — Overriding a method

JavaScript Example:

class Animal {
  speak() {
    console.log("Some sound");
  }
}

class Cat extends Animal {
  speak() {
    console.log("Meow!");
  }
}

const c = new Cat();
c.speak(); // "Meow!"

• The Cat class replaces the parent’s speak() with its own version.

Example 3 — Using super

JavaScript Example:

class Animal {
  speak() {
    console.log("Some sound");
  }
}

class Dog extends Animal {
  speak() {
    super.speak(); // call parent method
    console.log("Woof!"); // then add something
  }
}

const dog = new Dog();
dog.speak();
// "Some sound"
// "Woof!"

• super lets you call the parent’s version inside the child’s method.

In short:

Inheritance lets you build on existing classes instead of starting from scratch.