gistfile1.js

{
    init: function(elevators, floors) {
        passengersGoingDown = new Set();
        passengersGoingUp = new Set();

        idleElevators = [];

        function provisionElevatorOrAdd(queue){
            return function(){
                if(idleElevators.length){
                    // We should probbly pick the cloesest one.
                    var elevator = idleElevators.shift();
                    elevator.goToFloor(this.level);

                    elevator.goingUpIndicator(elevator.currentFloor < this.level);
                    elevator.goingDownIndicator(elevator.currentFloor > this.level);
                }else{
                    queue.add(this.level);
                }
            }
        }

        floors.forEach(function(floor){
            floor.on("up_button_pressed", provisionElevatorOrAdd(passengersGoingUp));
            floor.on("down_button_pressed", provisionElevatorOrAdd(passengersGoingDown));
        });

        elevators.forEach(function(elevator){
           elevator.on("idle", function(){
             idleElevators.push(elevator);
           });

           elevator.on("floor_button_pressed", function(floorNum){
            // Can this happen at any point? Docs are unclear.
            elevator.goToFloor(floorNum);
           });
           
           elevator.on("passing_floor", function(floorNum, direction){
             // If we are passing a floor, and we have space for more passangers, 
             // and they are going in the same direction, pick them up.
             if(elevator.loadFactor < 1 && (
                    elevator.goingUpIndicator() && passengersGoingUp.has(floorNum) || 
                    elevator.goingDownIndicator() && passengersGoingDown.has(floorNum))
                ){
                    elevator.goToFloor(floorNum, true);
                    elevator.checkDestinationQueue();
             }
           });

           elevator.on("stopped_at_floor", function(floorNum){
             // If we came to pickup passengers and the light is still on after pickup, we should reschedule.
             if(elevator.goingUpIndicator() && floors[floorNum].up){
                provisionElevatorOrAdd(passangersGoingUp)(floorNum);
             }
             if(elevator.goingDownIndicator() && floors[floorNum].down){
                provisionElevatorOrAdd(passangersGoingDown)(floorNum);
             }
             // Set the desitnation to the nearest queued floor.
             elevator.destinationQueue = elevator.destinationQueue.sort(function(a,b){return Math.abs(a-4) > Math.abs(b-4)});
             elevator.checkDestinationQueue();

             var nextFloor = elevator.destinationQueue[0];
             
             elevator.goingUpIndicator(nextFloor === undefined || floorNum < nextFloor);
             elevator.goingDownIndicator(nextFloor === undefined || floorNum > nextFloor);
           });
        });
    },
    update: function(dt, elevators, floors) {
        // We normally don't need to do anything here
    }
}