How do you create a subclass using extends?

extends sets up prototype-based inheritance between classes, and super() inside the subclass's constructor calls the parent class's constructor to initialize inherited state before adding subclass-specific properties.

class Animal {
  constructor(name) { this.name = name; }
}
class Dog extends Animal {
  constructor(name, breed) {
    super(name);
    this.breed = breed;
  }
}