heroes-bind.js

class Hero {
  constructor(name) {
      this.name = name
  }

  prepareForBattle(increaseCount) {
      console.log(`I am ${this.name}! Let's go fighting!`)
      increaseCount()
  }
}

class Battle {
  constructor(heroes) {
      this.heroes = heroes
      this.preparedHeroesCount = 0

      this.heroes.forEach(heroe => {
          heroe.prepareForBattle(this.increaseCount)
      })
  }

  increaseCount() {
      this.preparedHeroesCount++
      console.log(`${this.preparedHeroesCount} heroes are now ready to fight!`)
  }
}

const firstHero = new Hero('Flash')
const secondHero = new Hero('Thor')

new Battle([firstHero, secondHero])