Elevator solution by Oz, Tim and Adam

solution.js

{
    init: function(elevators, floors) {
        var self = this;
        var awaitingFloors = {}
        
        floors.forEach(function(floor){
            floor.on("up_button_pressed", function() {
                awaitingFloors[floor.floorNum()] = 1;
            })
            
            floor.on("down_button_pressed", function() {
                awaitingFloors[floor.floorNum()] = 1;
            })
        })
        
        elevators.forEach(function(elevator){
            elevator.on("idle", function() {
                targets = elevator.getPressedFloors()

                nearestRequestedFloor = self.findNearestFloor(elevator.currentFloor(), targets)
                nearestWaitingFloor = self.findNearestFloor(elevator.currentFloor(), Object.keys(awaitingFloors))
                
                if(nearestRequestedFloor && elevator.loadFactor() >= 0.5){
                    floor = nearestRequestedFloor
                }else{
                    floor = self.findNearestFloor(elevator.currentFloor(), [nearestRequestedFloor, nearestWaitingFloor])
                }

                if(floor){
                    elevator.goToFloor(floor);
                    delete awaitingFloors[floor]
                }else{
                    elevator.goToFloor(0);
                }
            });
        })
        
    },
    update: function(dt, elevators, floors) {
        // We normally don't need to do anything here
    },
    findNearestFloor: function(currentFloor, floors) {
        currentDistance = null
        result = null
        
        floors.forEach(function(floor){
            if(!floor){
                return
            }
            distance = Math.abs(currentFloor - floor)
            
            if(!currentDistance || currentDistance > distance){
                currentDistance = distance
                result = floor
            }
        })
        
        return result;
    }
}