Battle simulation for a D&D game

battle.js

let forces = [{
    name: 'enemy',
    health: 3360,
    random: 10
  }, {
    name: 'friendly',
    health: 2700,
    random: 6
  }]

let routedForces = {
  7: 600,
  15: 550,
  22: 800
}

let round = 0
let interval = setInterval(() => {
  console.log('battle: round ' + round++)
  forces.forEach((f, index) => {
    let strength = (f.health / 200).toFixed(0)
    let damage = ((Math.random() * f.random) + 1).toFixed(0) * strength
    if (damage === 0)
      damage = (Math.random() * f.random).toFixed(0) + 1

    if (routedForces[round] && index === 1) {
      damage += routedForces[round]
      console.log('heroes route ' + routedForces[round] + ' enemy forces')
    }

    forces[(index + 1) % 2].damageTaken = damage
  })

  forces = forces.map(f => {
    f.health -= f.damageTaken
    console.log(f.name + ' forces took ' + f.damageTaken + ' damage (' + f.health + ' remaining)')
    //delete f.damageTaken

    if (f.health < 0) {
      clearInterval(interval);
      console.log(f.name + ' forces were defeated')
    }
    return f
  })
}, 500)