Improve code legibility

elevator.js

 {
 	init: function(elevators, floors) {
 		console.clear();
-		console.log("Starting...");
 
 		// Get elevator/building info
+		let elevatorCount = elevators.length;
 		let floorCount    = floors.length;
-		let bottomFloor   = 0;
 		let topFloor      = floorCount - 1;
-		let elevatorCount = elevators.length;
+		let bottomFloor   = 0;
+
+		console.log("Starting (" + floorCount + " floors; " + elevatorCount + " elevator" + ((floorCount == 1) ? "s" : "") +")...");
 
-		// Direction/status constants
+		// Direction constants
 		const UP   = 0;
 		const DOWN = 1;
 		const IDLE = 2;
 		// Create a data structure for floor requests
 		let requests = [new Set(), new Set()];
 
-		// Register floor button presses
-		floors.forEach(function (floor) {
-			floor.on("up_button_pressed", function() { requests[UP].add(floor.floorNum); });
-			floor.on("down_button_pressed", function() { requests[DOWN].add(floor.floorNum); });
-		});
-
-
 		// ----
 		// Functions
 		// ----
 
-		function getClosestFloor(currentFloor, floorList){
-			let distance = floorCount;
+		function getClosestFloor(currentFloor, floorList, direction = IDLE, ignoredFloors = new Set()){
 			let closestFloor = currentFloor;
+			let distance     = floorCount;
+			let newDistance  = distance;
+
 			floorList.forEach(function(floorNum) {
-				let newDistance = Math.abs(currentFloor - floorNum);
-				if (newDistance < distance) {
+				switch (direction) {
+					case UP:
+						newDistance = floorNum - currentFloor;
+					case DOWN:
+						newDistance = currentFloor - floorNum;
+					case IDLE:
+						newDistance = Math.abs(floorNum - currentFloor);
+				}
+				if (newDistance < distance && newDistance > 0 && !(ignoredFloors.has(floorNum))) {
 					closestFloor = floorNum;
 					distance = newDistance;
 				}
 			})
-			return closestFloor;
+
+			if (closestFloor != currentFloor) {
+				return closestFloor;
+			} else {
+				throw new Error("No floor in selected direction");
+			}
+		}
+
+		function sendToNext(elevator, destinations, requests, restFloors) {
+			if (elevator.loadFactor() < 1) {
+				if (requests[UP].size > 0 || requests[DOWN].size > 0 || destinations.size > 0) {
+					let allStops = new Set([...destinations, ...requests[UP], ...requests[DOWN]]);
+					try {
+						elevator.goToFloor(getClosestFloor(elevator.currentFloor(), allStops));
+					} catch (e) {
+						elevator.goToFloor(restFloors[1]);
+					}
+				}
+			} else {
+				elevator.goToFloor(getClosestFloor(elevator.currentFloor(), destinations));
+			}
+		}
+
+		function bringClosestElevator(floorNum) {
+			let closestElevator = 0;
+			let distance        = floorCount;
+			let newDistance     = distance;
+
+			elevators.forEach(function (elevator) {
+				newDistance = Math.abs(elevator.currentFloor() - floorNum);
+				if (newDistance < distance) {
+					distance = newDistance;
+					closestElevator = elevators.indexOf(elevator);
+				}
+			});
+
+			elevators[closestElevator].goToFloor(floorNum);
+		}
+
+		function setDirection(elevator, direction){
+			switch (direction) {
+				case UP:
+					elevator.goingUpIndicator(true);
+					elevator.goingDownIndicator(false);
+					break
+				case DOWN:
+					elevator.goingUpIndicator(false);
+					elevator.goingDownIndicator(true);
+					break
+				default:
+					elevator.goingUpIndicator(true);
+					elevator.goingDownIndicator(true);
+			}
 		}
 
 		// ----
-		// Individual elevators
+		// Floors
+		// ----
+
+		floors.forEach(function (floor) {
+			floor.on("up_button_pressed", function() {
+				console.log("> Up request on floor[" + floor.level + "]");
+				requests[UP].add(floor.floorNum);
+				bringClosestElevator(floor.floorNum);
+			});
+			floor.on("down_button_pressed", function() {
+				console.log("> Down request on floor[" + floor.level + "]");
+				requests[DOWN].add(floor.floorNum);
+				bringClosestElevator(floor.floorNum);
+			});
+		});
+
+		// ----
+		// Elevators
 		// ----
 
 		elevators.forEach(function (elevator) {
-		elevator.on("floor_button_pressed", function(floorNum) { destinations.add(floorNum); });
 
-		// Basic elevator info
-		const elevatorIndex = elevators.indexOf(elevator);
+			// Basic elevator info
+			const elevatorIndex = elevators.indexOf(elevator);
 			const restFloors = [
 				(elevatorIndex + 0) * Math.floor(floorCount / (elevatorCount + 1)),
 				(elevatorIndex + 1) * Math.floor(floorCount / (elevatorCount + 1)),
 				(elevatorIndex + 2) * Math.floor(floorCount / (elevatorCount + 1))
 			]
 
+			elevator.on("floor_button_pressed", function(floorNum) {
+				console.log("> Pressed floor[" + floorNum + "] on elevator[" + elevatorIndex + "]");
+				destinations.add(floorNum);
+				sendToNext(elevator, destinations, requests, restFloors);
+			});
+
 			// Elevator variables
-			let status = UP;
 			let destinations = new Set();
 
-			// Go to designated starting floor
-			console.log("Sending elevator[" + elevatorIndex + "] to floor[" + restFloors[0] + "]")
-			elevator.goToFloor(restFloors[0]);
+			// Start
+			setDirection(elevator, UP); // Starts on the ground floor
+			console.log("> Sending elevator[" + elevatorIndex + "] to floor[" + restFloors[0] + "]");
+			elevator.goToFloor(restFloors[0]); // Closest rest floor
 
+			// Idle
 			elevator.on("idle", function() {
-				status = IDLE;
+				console.log("> Elevator[" + elevatorIndex + "] is idle")
+				setDirection(elevator, IDLE);
 				if (requests[UP].size == 0 && requests[DOWN].size == 0 && destinations.size == 0) {
 					elevator.goToFloor(restFloors[1]);
 				} else {
-					let allStops = new Set([...destinations, ...requests[UP], ...requests[DOWN]]);
-					elevator.goToFloor(getClosestFloor(elevator.currentFloor(), allStops));
+					sendToNext(elevator, destinations, requests, restFloors);
 				}
 			});
 
+			// Passing
 			elevator.on("passing_floor", function(floorNum, direction) {
-				if(requests[UP].has(floorNum) || requests[DOWN].has(floorNum) || destinations.has(floorNum)) {
+				if (elevator.loadFactor() < 1) {
+					if (requests[UP].has(floorNum) || requests[DOWN].has(floorNum) || destinations.has(floorNum)) {
+						elevator.goToFloor(floorNum, true);
+					}
+				} else if (destinations.has(floorNum)) {
 					elevator.goToFloor(floorNum, true);
 				}
 			});
 
+			// Stopped
 			elevator.on("stopped_at_floor", function(floorNum) {
+				console.log("> elevator[" + elevatorIndex + "] stopped at floor[" + floorNum + "]");
+				destinations.delete(floorNum);
 				requests[UP].delete(floorNum);
 				requests[DOWN].delete(floorNum);
-				destinations.delete(floorNum);
 
-				if (destinations.size > 0 || requests[UP] > 0 || requests[DOWN] > 0) {
-					let allStops = new Set([...destinations, ...requests[UP], ...requests[DOWN]]);
-					elevator.goToFloor(getClosestFloor(elevator.currentFloor(), allStops));
-				}
+				sendToNext(elevator, destinations, requests, restFloors);
 			});
 		});
 	},