Attempting to work out which algorithm to use

random-quality-test.js

var randomBytes = require('crypto').randomBytes;

var RANDOM_GENERATORS = {
  'randomUInt8Crypto': function() {
    return randomBytes(1).readUInt8();
  },
  'randomUInt8Old': function() {
    return 0 | Math.random() * 256;
  }
};

var ALGORITHMS = {
  'Current': function(randomUInt8, radix) {
   return 0 | Math.random() * radix;
  },
  'While Loop': function(randomUInt8, radix) {
    var maxRandom = 255 - (256 % radix);

    var randomValue;
    do {
      randomValue = randomUInt8();
    } while (randomValue > maxRandom);

    return randomValue % radix;
  },
  'Round with radix to 0': function(randomUInt8, radix) {
    var result = Math.round(randomUInt8() / 256 * radix);
    return result === radix ? 0 : result;
  },
  'Floor': function(randomUInt8, radix) {
    return Math.floor(randomUInt8() / 256 * radix);
  }
};

var RADIX = 10;
var ROUNDS = 10000000;
var IDEAL = ROUNDS / RADIX;

var MORE_DETAIL = false;

function devation(value) {
  return IDEAL - value;
}

function test(algoKey, randomUInt8Key) {
  var algo = ALGORITHMS[algoKey];
  var randomUInt8 = RANDOM_GENERATORS[randomUInt8Key];

  var results = [];
  for (var i = 0; i < RADIX; i++) { results[i] = 0; }

  var before = Date.now();
  for (var i = 0; i < ROUNDS; i++) { results[algo(randomUInt8, RADIX)] += 1; }
  var after = Date.now();

  var deviations = results.map(devation);
  var averageDeviation = deviations.map(Math.abs).reduce(function(a, b) { return a + b; }) / RADIX;

  console.log(algoKey, 'with', randomUInt8Key, 'took', after - before, 'millis, with', averageDeviation, '"average" deviance');
  if (MORE_DETAIL) {
    results.forEach(function(result, idx) {
      console.log('', idx, '\t', result, '\t', devation(result));
    });
  }
}

Object.keys(ALGORITHMS).map(function(algoKey) {
  Object.keys(RANDOM_GENERATORS).map(function(randomUInt8Key) {
    test(algoKey, randomUInt8Key);
  });
});