Elevator Saga 02 - Getting better...

elevatorSaga02.js

{
    init: function(elevators, floors) {

        console.clear()

        const DO_NOT_STOP_THRESHOLD = 0.7
		
        var floorsWaitingForUp = new Set()
        var floorsWaitingForDown = new Set()        

        // TODO:  You might consider making this a function of an Elevator object...
        function refreshElevatorIndicator(elevator) {
            var direction = directionOfNextStop(elevator)
            if (direction == "up") {
                goingUp(elevator)
            }
            else if (direction == "down") {
                goingDown(elevator)
            }
            else if (elevator.currentFloor() === 0) {
                goingUp(elevator)
            }
            else if (elevator.currentFloor() === floors.length - 1) {
                goingDown(elevator)
            }
            else {
                idle(elevator)
            }
        }

        // TODO:  You also might consider making these functions of an Elevator object...
        function goingDown(elevator) {
            elevator.goingUpIndicator(false)
            elevator.goingDownIndicator(true)
            console.debug(elevator.name + " is going down", elevator.destinationQueue)
        }
        function goingUp(elevator) {
            elevator.goingUpIndicator(true)
            elevator.goingDownIndicator(false)
            console.debug(elevator.name + " is going up", elevator.destinationQueue)
        }
        function idle(elevator) {
            elevator.goingUpIndicator(true)
            elevator.goingDownIndicator(true)
            console.debug(elevator.name + " is idle", elevator.destinationQueue)
        }

        // TODO:  You might also want consider making this a function of an Elevator object...
        function directionOfNextStop(elevator) {
            if (elevator.destinationQueue.length === 0 || elevator.destinationQueue[0] === elevator.currentFloor()) {
                return "stopped"
            }
            else if (elevator.destinationQueue[0] > elevator.currentFloor()) {
                return "up"
            }
            else if (elevator.destinationQueue[0] < elevator.currentFloor()) {
                return "down"
            }
            else {
                console.warn("directionOfNextStop() isn't working how you expect it to...", elevator)
            }
        }

        // TODO:  You might also want consider making this a function of an Elevator object...
        function smartGoToFloor(elevator, targetFloor) {
            var startingDirection = directionOfNextStop(elevator)

            // NOTE:  There's an implicit expectation here that people will pay attention to the Elevator Indicators...
            if (startingDirection === "stopped") {
                elevator.goToFloor(targetFloor)
            }
            else if (startingDirection === "up") {
                var insertBeforeIndex = 0;
                while (insertBeforeIndex < elevator.destinationQueue.length && elevator.destinationQueue[insertBeforeIndex] < targetFloor) {++insertBeforeIndex}
                elevator.destinationQueue.splice(insertBeforeIndex, 0, targetFloor)
                elevator.checkDestinationQueue();
            }
            else if (startingDirection === "down") {
                var insertBeforeIndex = 0;
                while (insertBeforeIndex < elevator.destinationQueue.length && elevator.destinationQueue[insertBeforeIndex] > targetFloor) {++insertBeforeIndex}
                elevator.destinationQueue.splice(insertBeforeIndex, 0, targetFloor)
                elevator.checkDestinationQueue();
            }
            else {
                console.warn("smartGoToFloor() isn't working how you expect it to...", elevator, targetFloor)
            }

            console.debug("Queue Updated for " + elevator.name, elevator.destinationQueue)
        }

        console.debug("Number of Floors = " + floors.length)

        floors.forEach(floor => {
            floor.on("up_button_pressed", function() {
                floorsWaitingForUp.add(floor.floorNum())
                console.debug("Up Call from Floor " + floor.floorNum(), floorsWaitingForUp)
            })            
            floor.on("down_button_pressed", function() {
                floorsWaitingForDown.add(floor.floorNum())
                console.debug("Down Call from Floor " + floor.floorNum(), floorsWaitingForDown)
            })
        })

        console.debug("Number of Elevators = " + elevators.length)

        elevators.forEach(function (elevator, index) {
            elevator.name = "Elevator " + (index + 1)
            console.debug("Initial Queue for " + elevator.name, elevator.destinationQueue)

            elevator.on("floor_button_pressed", function(floorNum) {
                console.debug(elevator.name + " sent to Floor " + floorNum + " from " + elevator.currentFloor())
                smartGoToFloor(elevator, floorNum)
                refreshElevatorIndicator(elevator)
            })
            elevator.on("stopped_at_floor", function(floorNum) {
                // TODO:  floorsWaitingForUp/floorsWaitingForDown should be updated here because people will get in if the direction of travel is correct...
                console.debug(elevator.name + " stopped at " + floorNum, elevator.destinationQueue)
                refreshElevatorIndicator(elevator)
            })
            elevator.on("passing_floor", function(floorNum, direction) {
                console.debug(elevator.name + " passing " + floorNum + " moving " + direction)
                if (elevator.loadFactor() < DO_NOT_STOP_THRESHOLD) {                    
                    if (direction === "up" && floorsWaitingForUp.has(floorNum)) {
                        elevator.goToFloor(floorNum, true)
                        floorsWaitingForUp.delete(floorNum)
                        console.debug("Queue Updated for " + elevator.name, elevator.destinationQueue)
                    }
                    if (direction === "down" && floorsWaitingForDown.has(floorNum)) {
                        elevator.goToFloor(floorNum, true)
                        floorsWaitingForDown.delete(floorNum)
                        console.debug("Queue Updated for " + elevator.name, elevator.destinationQueue)
                    }
                }
            })
            elevator.on("idle", function() {
                console.debug(elevator.name + " was idle", elevator.destinationQueue)                
                // TODO:  Don't priorise Up over Down...
                if (floorsWaitingForUp.size > 0) {
                    let floorNum = floorsWaitingForUp.values().next().value
                    elevator.goToFloor(floorNum)
                    floorsWaitingForUp.delete(floorNum)
                    console.debug("Queue Updated for " + elevator.name, elevator.destinationQueue)
                }
                else if (floorsWaitingForDown.size > 0) {
                    let floorNum = floorsWaitingForDown.values().next().value
                    elevator.goToFloor(floorNum)
                    floorsWaitingForDown.delete(floorNum)
                    console.debug("Queue Updated for " + elevator.name, elevator.destinationQueue)
                }
            });
        })

    },

	update: function(dt, elevators, floors) {
	}
}

This is what I ended up with after about an hour. It will pass many of the challenges but there is still room for improvement...

• Idle Elevators only look for work at the moment when they become Idle (then they sit and wait for a passenger on the current floor)
• Idle Elevators should be smarter about work selection (e.g. an Idle Elevator on the (n-1)th floor should favour a waiting passenger from the nth floor rather than going back to the ground floor - subject to passenger wait times)

Points of note...

• I gave Elevators names to help support...
• Extensive logging to help debug and improve
• Additional data structures (Sets) are used