My Elevator Saga solution

elevator.js

{
  init: function(elevators, floors) {
    var MAX_LOAD = 4, elevatorSize = elevators.length;
    var fetchElevator = function (floor, callback) {
      var candidateIdx = -1, candidateDiff = elevatorSize + 1, candidateLoadFactor = .4;
      var currf, fdiff;
      for (var i = 0; i < elevatorSize; i++) {
        currf = elevators[i].currentFloor();
        fdiff = Math.abs(currf - floor.floorNum());
        if (elevators[i].destinationQueue.length === 0 &&
            elevators[i].loadFactor() <= candidateLoadFactor &&
            fdiff < candidateDiff) {
          candidateIdx = i;
          candidateDiff = fdiff;
          candidateLoadFactor = elevators[i].loadFactor();
        }
      }
      if (candidateIdx === -1) {
        setTimeout(function () {
          fetchElevator(floor, callback);
        }, 10);
        return;
      }
      return callback(elevators[candidateIdx]);
    };
    var sortQueue = function (floorNum, elevator) {
      var newQueue = [], oldQueue = elevator.destinationQueue, l = oldQueue.length;
      outerLoop:
      for (var i = 0; i < l; i++) {
        if (newQueue.length === 0) {
          newQueue.push(oldQueue[i]);
          continue;
        }
        for (var j = 0; j < newQueue.length; j++) {
          if (Math.abs(floorNum - oldQueue[i]) < Math.abs(floorNum - newQueue[j])) {
            newQueue.splice(j, 0, oldQueue[i]);
            continue outerLoop;
          }
        }
        newQueue.push(oldQueue[i]);
      }
      return newQueue;
    };

    _.each(floors, function (floor) {
      var num = floor.floorNum();
      floor.on("up_button_pressed down_button_pressed", function () {
        fetchElevator(floor, function (elevator) {
          elevator.goToFloor(num);
        })
      });
    });

    _.each(elevators, function (elevator) {
      elevator.on("floor_button_pressed", function onFloorButtonPressed(floorNum) {
        if (this.destinationQueue.indexOf(floorNum) > -1) {
          return
        } else {
          this.goToFloor(floorNum);
          this.destinationQueue = sortQueue(this.currentFloor(), this);
          this.checkDestinationQueue();
        }
      }).on("stopped_at_floor", function () {
        if (this.destinationQueue.length > 1) {
          this.destinationQueue = sortQueue(this.currentFloor(), this);
          this.checkDestinationQueue();

          if (this.destinationQueue.length > 2) {
            if (this.destinationQueue[0] > this.destinationQueue[1]) {
              this.goingUpIndicator(false);
              this.goingDownIndicator(true);
            } else if (this.destinationQueue[0] < this.destinationQueue[1]) {
              this.goingUpIndicator(true);
              this.goingDownIndicator(false);
            }
          }
        } else {
          this.goingUpIndicator(true);
          this.goingDownIndicator(true);
        }
      }).on("idle", function () {
        this.goToFloor(parseInt(Math.random() * 8));
      });
    });

    // init
    for (var i = 1; i < elevators.length; i++) {
      elevators[i].goToFloor(i*2);
    }
  },
  update: function(dt, elevators, floors) {
  }
}