elevatorsaga.com solution

{
    init: function(elevators, floors) {
        var stopRequested = [];
        _.each(floors, function(floor) {
            floor.on("up_button_pressed down_button_pressed", function() {
                var elevatorsDistance = _.map(elevators, function(elevator) { return [elevator, elevator.loadFactor()* (elevator.currentFloor() - floor.level)]; });
                var choosenElevatorDistance = _.min(elevatorsDistance, function(elevatorDistance){ return elevatorDistance[1]; });
                var choosenElevator = choosenElevatorDistance[0];
                choosenElevator.goToFloor(floor.level);
            }); 
        });
        _.each(elevators, function(elevator) {
            elevator.on("floor_button_pressed", function(floorNum) {
                elevator.goToFloor(floorNum, true);
            });
            elevator.on("idle", function() {
                elevator.goToFloor(0);
            });
        });
    },
    update: function(dt, elevators, floors) {
        // We normally don't need to do anything here
    }
}