Article: Composition Alone Can't Replace Inheritance - original inheritance example

originalInheritanceExample.js

export class Monster {
  constructor() {
    if (this.constructor === Monster) {
      throw new Error('This is an abstract class. Do not instantiate it directly.');
    }
  }

  attack() {
    playHurtAnimation()
  }

  die() {
    userInventory.add(this.dropLoot())
    removeFromUi(this)
  }

  dropLoot() {
    throw new Error('This is an abstract function. It should be shadowed.')
  }
}

export class Slime extends Monster {
  dropLoot() {
    return [new SlimeBall()]
  }
}

export class Skeleton extends Monster {
  dropLoot() {
    return [new Bone()]
  }
}

export class Clown extends Monster {
  dropLoot() {
    return [new Key()]
  }

  attack() {
    super.attack()
    if (itsTime()) {
      showCutScene()
    }
  }
}