class Animal {
  constructor(name) {
    this.name = name;
  }

  speak() {
    return `${this.name} makes a sound`;
  }
}

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

  bark() {
    return `${this.name} barks loudly!`;
  }
}

const rex = new Dog('Rex', 'Labrador');
console.log(rex.speak()); // "Rex makes a sound" — inherited
console.log(rex.bark());  // "Rex barks loudly!" — own method

class Animal {
  speak() {
    return `${this.name} makes a sound`;
  }
}

class Dog extends Animal {
  speak() {
    return `${this.name} barks!`; // overrides parent
  }
}

const rex = new Dog('Rex');
console.log(rex.speak()); // "Rex barks!" — Dog's version

class Animal {
  speak() {
    return `${this.name} makes a sound`;
  }
}

class Dog extends Animal {
  speak() {
    // Call parent method, then extend it
    const parentMessage = super.speak();
    return `${parentMessage} — specifically, it barks!`;
  }
}

const rex = new Dog('Rex');
console.log(rex.speak());
// "Rex makes a sound — specifically, it barks!"

flowchart TD
    A["Animal\n- constructor(name)\n- speak()"]
    B["Mammal extends Animal\n- constructor(name, hasFur)\n- walk()"]
    C["Dog extends Mammal\n- constructor(name, breed)\n- bark()"]
    D["rex = new Dog('Rex', 'Lab')"]

    A --> B --> C
    C --> D

    D -.->|"rex.speak() → Animal.prototype"| A
    D -.->|"rex.walk() → Mammal.prototype"| B
    D -.->|"rex.bark() → Dog.prototype"| C

class Animal {
  constructor(name) {
    this.name = name;
  }
}

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

// Without super:
class BadDog extends Animal {
  constructor(name, breed) {
    // ❌ ReferenceError: Must call super first
    this.breed = breed;
    super(name);
  }
}

function createBase(prefix) {
  return class {
    greet() { return `${prefix}: Hello!`; }
  };
}

class Specific extends createBase('API') {
  // ...
}

const obj = new Specific();
console.log(obj.greet()); // "API: Hello!"