class Soldier {
  handEquip(weapon) {
    this.equipedWeapon = weapon;
  }
  useHandEquipmentAgainst(enemy) {
    this.equipedWeapon.shoot(enemy);
  }
}

class MachineGun {
  open(bottle) {
    alert('*Opening A Bottle With The Machine Gun*');
  }
  shoot(enemy) {
    alert('*Shooting The Machine Gun Against The Enemy*');
  }
}

// ...

const john = new Soldier();
john.handEquip(new MachineGun());
john.useHandEquipmentAgainst(new Soldier());