utils.js

var shuffleArray;
(function () {
  shuffleArray = function (array){
    var currentIndex = array.length, temporaryValue, randomIndex ;

    // While there remain elements to shuffle...
    while (0 !== currentIndex) {

      // Pick a remaining element...
      randomIndex = Math.floor(Math.random() * currentIndex);
      currentIndex -= 1;

      // And swap it with the current element.
      temporaryValue = array[currentIndex];
      array[currentIndex] = array[randomIndex];
      array[randomIndex] = temporaryValue;
    }

    return array;
  };

  if (!Object.assign) {
    Object.defineProperty(Object, 'assign', {
      enumerable: false,
      configurable: true,
      writable: true,
      value: function(target) {
        if (target === undefined || target === null) {
          throw new TypeError('Cannot convert first argument to object');
        }

        var to = Object(target);
        for (var i = 1; i < arguments.length; i++) {
          var nextSource = arguments[i];
          if (nextSource === undefined || nextSource === null) {
            continue;
          }
          nextSource = Object(nextSource);

          var keysArray = Object.keys(Object(nextSource));
          for (var nextIndex = 0, len = keysArray.length; nextIndex < len; nextIndex++) {
            var nextKey = keysArray[nextIndex];
            var desc = Object.getOwnPropertyDescriptor(nextSource, nextKey);
            if (desc !== undefined && desc.enumerable) {
              to[nextKey] = nextSource[nextKey];
            }
          }
        }
        return to;
      }
    });
  }
})();