My algorithm to Elevator Saga: http://play.elevatorsaga.com/

elevator_algorithm.js

{
    init: function(elevators, floors) {
        function isFloorQueued (floorNum, elevator) {
            if (elevator) {
                let destinationQ = elevator.destinationQueue;
                for (let destIndex = 0; destIndex < destinationQ.length; ++destIndex) {
                    if (destinationQ[destIndex] == floorNum){
                        return true;
                    }
                }
            }
            return false;
        }

        for (let elevIndex = 0; elevIndex < elevators.length; ++elevIndex) {
            let elevator = elevators[elevIndex];
            elevator.on("idle", function() {
                this.goToFloor(0);
            });

            elevator.on("floor_button_pressed", function (floorNum) {
                if (!isFloorQueued(floorNum, this)) {
                    this.goToFloor(floorNum);
                }
                if (this.currentFloor() == 0) {
                    this.destinationQueue.sort();
                }
                else if (this.currentFloor() == floors.length-1) {
                    this.destinationQueue.sort(function(a, b){return b-a});
                }
            });

            elevator.on("stopped_at_floor", function (floorNum) {
            });

            elevator.on("passing_floor", function (floorNum) { // if passing a queued floor and full, just stop
                if (this.loadFactor() == 1 && isFloorQueued(floorNum, this)) this.goToFloor(floorNum, true);
            })
        }

        for (let floorIndex = 0; floorIndex < floors.length; ++floorIndex) {
            let floor = floors[floorIndex];
            floor.on("up_button_pressed down_button_pressed", function() {
                let isQueued = false;
                for (let elevIndex = 0; elevIndex < elevators.length; ++elevIndex) {
                    let elevator = elevators[elevIndex];
                    if (isFloorQueued(floor, elevator)) isQueued = true;
                }
                
                if (! isQueued) { // if not queued, find closest non-full elevator
                    let eIndex = 0,
                        minDistance = Number.POSITIVE_INFINITY;
                    for (let elevIndex = 0; elevIndex < elevators.length; ++elevIndex) {
                        let elevator = elevators[elevIndex];
                        let currentDistance = Math.abs(floorIndex - elevator.currentFloor());
                        if (currentDistance < minDistance && elevator.loadFactor() != 1) {
                            minDistance = currentDistance;
                            eIndex = elevIndex;
                        }
                    }
                    if (elevators[eIndex].loadFactor() != 1)
                        elevators[eIndex].goToFloor(floorIndex);
                }
            });
        }
    },
        update: function(dt, elevators, floors) {
            // We normally don't need to do anything here
        }
}