enemies.js

  //
  // Werewolf, it shall have 30 HP and 5 DMG
  class Werewolf extends Enemy {
      constructor(){
        super('Werewolf', 30, 5);
      }
  }
  // Vampire, it shall have 50 HP and 10 DMG
  class Vampire extends Enemy {
    constructor(){
      super('Vampire', 50, 10);
    }
  }
  // AntonioZequila, it shall have 80 HP, 20 DMG and should growl a different sound
  class AntonioZequila extends Enemy {
    
    constructor(){
        super("AntonioZequila",80,20)
    }
    growl() {
      console.log('Antonio!!!!');
    }
  }

  // Then create an EnemyFactory class that can be used to create random instances of enemies, like the following:
  class EnemyFactory {
    static create(){

        const enemies = [Vampire,AntonioZequila,Werewolf]
        const count = enemies.length 
        const ranges = Array.from(Array(count).keys()).map(i => ((i+1)/count))
        
        const random = Math.random()
        
        let founded = false
        let istance
        ranges.forEach((r,index) => {
            if(!founded &&  random < r){
                founded = true
                istance = enemies[index]
            }
        })
        return new istance()
    }
  }