D&D Bonus XP Analysis

let experimentCount = 10000;
console.log(`Performing ${experimentCount} experiments using two fighters until one of them reaches level 12.`);
repeatExperiments(experimentCount, 5, 0.2);
repeatExperiments(experimentCount, 10, 0.2);
repeatExperiments(experimentCount, 20, 0.2);

repeatExperiments(experimentCount, 5, 0.4);
repeatExperiments(experimentCount, 10, 0.4);
repeatExperiments(experimentCount, 20, 0.4);

repeatExperiments(experimentCount, 5, 0.8);
repeatExperiments(experimentCount, 10, 0.8);
repeatExperiments(experimentCount, 20, 0.8);

repeatExperiments(experimentCount, 5, 1.6);
repeatExperiments(experimentCount, 10, 1.6);
repeatExperiments(experimentCount, 20, 1.6);

function repeatExperiments(experimentCount, bonusXp, xpGainFactor) {
    let sumMattered = 0;
    let sumSessions = 0;

    for(let i = 0; i < experimentCount; i++) {
        let results = performExperiment(bonusXp, xpGainFactor);
        sumMattered += results.mattered;
        sumSessions += results.sessions;
    }

    let ratio = Math.round(1000 * sumMattered / sumSessions) / 10;
    let averageSessions = Math.round(sumSessions / experimentCount);
    let averageMattered = Math.round(ratio * 0.01 * averageSessions);

    console.log(`${bonusXp}% Bonus XP was on average relevant to ${averageMattered} sessions (${ratio}%), ${averageSessions} sessions to hit level 12.`);
}

function performExperiment(bonusXp, xpGainFactor) {
    let bonusXpPercent = (bonusXp * 0.01) + 1;
    let fighterXp = [200,400,800,1500,3000,6500,12000,20000,30000,40000,60000];

    let fighter1 = { xp: 0, level: 1 };
    let fighter2 = { xp: 0, level: 1 };
    let sessions = 0;
    let bonusXpMattered = 0;

    for(let i = 0; i < 200; i++) {
        sessions++;
        let threshold = fighter1.xp < 20000 ? fighter1.xp : 20000;
        threshold = threshold < 200 ? 200 : threshold;

        let xpGain = threshold * xpGainFactor * Math.random();

        fighter1.xp += Math.round(xpGain);
        fighter2.xp += Math.round(xpGain * bonusXpPercent);

        fighter1.level = getFighterLevel(fighter1.xp);
        fighter2.level = getFighterLevel(fighter2.xp);

        //console.log(`Session ${sessions}. Fighter ${fighter1.level} (${fighter1.xp}), Fighter ${fighter2.level} (${fighter2.xp})`);

        if (fighter1.level != fighter2.level) {
            bonusXpMattered++;
        }

        if (fighter1.level == 12) break;
    }

    function getFighterLevel(xp) {
        let level = fighterXp.findIndex(x => x > xp);
        if (level == -1) level = 11;
        return level + 1;
    }

    return { sessions, mattered: bonusXpMattered };
}