Attacker vs Defender with big armies in risk

riskroll.js

function roll() {
  return Math.ceil(Math.random() * 6);
}

function compare() {
  var one = [roll(), roll(), roll()].sort(function (a, b) { return b-a }).slice(0,2);
  var two = [roll(), roll()].sort(function (a, b) { return b-a });
  var score = 0;

  one.forEach(function (item, index) {
    if (item > two[index]) {
      score++;
    } else {
      score--;
    }
  });

  return score;
}

var wins = 0;
var losses = 0
var ties = 0;

for (var i = 0; i < 1000000; i++) {
  var result = compare();
  if (result > 0) {
    wins++;
  } else if (result < 0) {
    losses++;
  } else {
    ties++
  }
}
console.log(wins, losses, ties);