An effecient random selector observing weighted sets

Random selection from weighted set

(function(){
  function verify(weights, chosen, trialCount) {
    var variance = 0, ttl = chosen.length;
    for(var ix = 0; ix < ttl; ix++) {
      console.log(weights[ix],  chosen[ix] / trialCount);
      variance += Math.sqrt(Math.abs(Math.pow(weights[ix], 2) - Math.pow(chosen[ix] / trialCount, 2)));
    }
    console.log(variance / ttl);
  }

  function array(count, fn) { 
    return Array.apply(0, Array(count)).map(fn);
  }

  function getRandomInt(min, max) {
    min = Math.ceil(min);
    max = Math.floor(max);
    return Math.floor(Math.random() * (max - min)) + min;
  }

  function Sequence(max) {
    var 
      ix = 0,
      current = max - 1,
      slosh,
      list = array(max, function(){ return ix++ });

    return function() {
      var index = (current === 0) ? 0 : getRandomInt(0, current);
          res = list[index];

      slosh = list[index];
      list[index] = list[current];
      list[current] = slosh;

      if(current == 0) {
        current = max;
      }

      current --;
      return res;
    }
  }


  var number_of_weights = 0,
      number_of_trials = 1000,//0000,
      scaling_factor = 1/30,
      weights = [],
      ttl = 0,
      index = 0,
      max_weight;
  
  while(true) {
    index = scaling_factor * Math.random();
    if(ttl + index > 1.0) {
      index = 1.0 - ttl;
      weights.push(index);
      break;
    }
    weights.push(index);
    ttl += index;
  }
  number_of_weights = weights.length;
  max_weight = 0.99 * weights.reduce(function(a, b) { return a > b ? a : b });

  /*
  var buckets = new Array(10).map(function() { return [] });

  weights.forEach(function(sample) {
    buckets[sample.toString()[2]].push( sample );
  });
  
  */

  var attempt_machine = Sequence(number_of_weights);

  // For the bucket we need to make sure that the things in the '9' bucket
  // get chosen more than the '8' and so on.
  //
  // so first we have a sample, this will be our sample for the duration 
  // of our choice.
  var sample, attempt, trials = 0, ix, chosen = array(number_of_weights, function() { return 0 });
  
  for(ix = 0; ix < number_of_trials; ix ++) {
    sample = Math.random() * max_weight;

    while(true){ 
      attempt = attempt_machine();
      if(weights[attempt] > sample) {
        break;
      }
      trials++;
    };
    chosen[attempt] ++;
  }
  verify(weights, chosen, number_of_trials);
  console.log(trials / number_of_trials);
})();