Favor Composition Over Inheritance

Deep inheritance chains are brittle. When requirements change, you end up fighting the hierarchy.

// dirty — inheritance chain
class Animal { constructor(name) { this.name = name; } }
class Dog extends Animal { bark() { return this.name + ' says: woof'; } }
class Cat extends Animal { meow() { return this.name + ' says: meow'; } }

Refactor using composition: create createAnimal(name, sound) that returns an object with a speak() method. No classes, no inheritance.
solve(name, sound) calls createAnimal(name, sound).speak().

solve('Rex', 'woof') → 'Rex says: woof'