bracket.js

function choice(set, choice) {
    return set.indexOf(choice) > -1 ? choice : '';
}

function blankArray(l) {
    return (new Array(l)).map(function(){ return ''; });
}

Array.prototype.pairChoice = function(c) {
    return this.pairs().map(function(pair) { return choice(pair, c); });
};

Array.prototype.elevate = function(team, step) {
    var set = this
      , i = set.indexOf(team);

    if (typeof step === 'undefined') { step = set.length - 1; }

    var loop = function(acc, set) {
        var beyond = (acc + 1) > step
          , l = set[acc].length;
        if (l == 2) { return set.ipush(beyond ? blankArray(1) : [team]); }
        return loop(acc + 1, set.ipush(beyond ? blankArray(l / 2) : set[acc].pairChoice(team) ));
    };
    return loop(0, [set]);
}