Added crude client rendering with pixi.js

Added keyboard controlling
Added fixed ball reflections on right paddle
added reflections on screen borders
Added goal (miss the paddle) detection

PongGame/Hubs/GameState.cs

@@ -0,0 +1,8 @@
+namespace PongGame;
+
+public enum GameStatus {
+    WaitingForPlayers,
+    InProgress,
+    Finished,
+    Paused,
+}

PongGame/Hubs/IPongClient.cs

@@ -0,0 +1,7 @@
+namespace PongGame.Hubs;
+
+public interface IPongClient {
+    Task GameStateChanged(GameStatus state);
+    Task ReceiveGameState(PongGameState state);
+    Task UsernameChanged(string value);
+}

PongGame/Hubs/PongGameState.cs

@@ -0,0 +1,110 @@
+using System.Drawing;
+
+namespace PongGame.Hubs;
+
+/// <summary>
+/// Pong game state saving the positions of the paddles and the ball.
+/// The Pong board has aspect ratio 1:2 with height 500 and width 1000.
+/// </summary>
+public struct PongGameState {
+    public const float HEIGHT = 500.0f;
+    public const float WIDTH = 2 * HEIGHT;
+    public const float PADDLE1_OFFSET = WIDTH / 20;
+    public const float PADDLE2_OFFSET = WIDTH - PADDLE1_OFFSET;
+
+    public static readonly PongGameState Initial = new() {
+        BallState = PongBallState.Initial,
+        Paddle1 = PongPaddleState.Initial,
+        Paddle2 = PongPaddleState.Initial,
+        Status = GameStatus.WaitingForPlayers,
+        WinnerLeft = null
+    };
+
+    public PongPaddleState Paddle1;
+    public PongPaddleState Paddle2;
+    public PongBallState BallState;
+    public GameStatus Status;
+    public bool? WinnerLeft;
+
+    public static void Update(ref PongGameState state) {
+        if (state.Status is not GameStatus.InProgress) return;
+
+        PongPaddleState.Update(ref state.Paddle1);
+        PongPaddleState.Update(ref state.Paddle2);
+        PongBallState.Update(ref state.BallState);
+        var ballX = state.BallState.Pos.X;
+        if (ballX is < 0 or > WIDTH) {
+            state.WinnerLeft = ballX < 0;
+            state.Status = GameStatus.Finished;
+            return;
+        }
+
+        Collide(in state.Paddle1, ref state.BallState, true);
+        Collide(in state.Paddle2, ref state.BallState, false);
+    }
+
+    private static void Collide(in PongPaddleState paddle, ref PongBallState ballState, bool left) {
+        var paddleX = left ? PADDLE1_OFFSET : PADDLE2_OFFSET;
+        var intersection = RectangleF.Intersect(paddle.GetCollider(paddleX), ballState.GetCollider());
+        if (intersection.IsEmpty) return;
+
+        // TODO: continuous collision
+        var ratio = (ballState.Pos.Y - paddle.Height + PongPaddleState.PADDLE_HALF_LENGTH) / PongPaddleState.PADDLE_LENGTH;
+
+        // TODO: lesser angles
+        var upAngle = left ? MathF.PI * 3 / 8 : MathF.PI * 5 / 8;
+        var downAngle = left ? -MathF.PI * 3 / 8 : MathF.PI * 11 / 8;
+
+        // TODO: reflect ball on surface instead of launching
+        ballState.BallAngle = ratio * downAngle + (1 - ratio) * upAngle;
+    }
+
+    public struct PongBallState {
+        public const float BALL_SPEED = 2 * BALL_RADIUS;
+        public const float BALL_RADIUS = HEIGHT / 125;
+
+        public static readonly PongBallState Initial = new() {
+            BallAngle = 0.0f,
+            Pos = new() {
+                X = WIDTH / 2,
+                Y = HEIGHT / 2
+            }
+        };
+
+        public PointF Pos;
+        public float BallAngle;
+
+        public static void Update(ref PongBallState state) {
+            var (dy, dx) = MathF.SinCos(state.BallAngle);
+            state.Pos.X += BALL_SPEED * dx;
+            state.Pos.Y -= BALL_SPEED * dy;
+
+            if (state.Pos.Y < BALL_RADIUS
+                || state.Pos.Y > HEIGHT - BALL_RADIUS)
+                state.BallAngle = 2 * MathF.PI - state.BallAngle;
+        }
+
+        public RectangleF GetCollider() => new(Pos.X - BALL_RADIUS, Pos.Y - BALL_RADIUS, 2 * BALL_RADIUS, 2 * BALL_RADIUS);
+    }
+
+    public struct PongPaddleState {
+        public const float PADDLE_LENGTH = HEIGHT / 10;
+        public const float PADDLE_HALF_LENGTH = PADDLE_LENGTH / 2;
+        public const float PADDLE_WIDTH = PADDLE_LENGTH / 5;
+        public const float PADDLE_SPEED = 8;
+
+        public static readonly PongPaddleState Initial = new() {
+            Direction = PongPaddleDirection.Stop,
+            Height = HEIGHT / 2
+        };
+
+        public float Height;
+        public PongPaddleDirection Direction;
+
+        public static void Update(ref PongPaddleState state) {
+            state.Height = Math.Clamp(state.Height - ((int)state.Direction) * PADDLE_SPEED, PADDLE_HALF_LENGTH, HEIGHT - PADDLE_HALF_LENGTH);
+        }
+
+        public RectangleF GetCollider(float x) => new(x - PADDLE_WIDTH / 2, Height - PADDLE_HALF_LENGTH, PADDLE_WIDTH, PADDLE_LENGTH);
+    }
+}

PongGame/Hubs/PongHub.cs

@@ -0,0 +1,76 @@
+using Microsoft.AspNetCore.SignalR;
+
+namespace PongGame.Hubs;
+
+public class PongHub : Hub<IPongClient> {
+    private const string PLAYER_KEY = "PLAYER";
+    private readonly PongLobby Lobby;
+    private readonly ILogger<PongHub> Logger;
+
+    public PongHub(PongLobby lobby, ILogger<PongHub> logger) : base() {
+        Lobby = lobby;
+        Logger = logger;
+    }
+
+    private PongPlayer Player {
+        get => (Context.Items.TryGetValue(PLAYER_KEY, out var player) ? player as PongPlayer : null)
+            ?? throw new InvalidProgramException("Player was not assigned at connection start!");
+        set => Context.Items[PLAYER_KEY] = value;
+    }
+
+    public override Task OnConnectedAsync() {
+        Player = Lobby.CreatePlayer();
+        Player.Client = Clients.Client(Context.ConnectionId);
+        Player.Username = "Anon";
+        return Task.CompletedTask;
+    }
+
+    private void AssertNotInRoom() {
+        if (Player.ConnectedRoom is PongRoom currentRoom)
+            throw new HubException($"User is already connected to room [{currentRoom}]");
+    }
+
+    private PongRoom AssertInRoom() {
+        if (Player.ConnectedRoom is not PongRoom currentRoom)
+            throw new HubException($"User is not in any room!");
+        return currentRoom;
+    }
+
+    public Task<string> CreateRoom() {
+        AssertNotInRoom();
+        var room = Lobby.CreateRoom(Player);
+        return Task.FromResult(room.ID);
+    }
+
+    public Task<string> JoinRoom(string roomId) {
+        AssertNotInRoom();
+        var room = Lobby.JoinRoom(Player, roomId);
+        return Task.FromResult(room.ID);
+    }
+
+    public Task MovePaddle(int dir) {
+        var room = AssertInRoom();
+        var direction = (PongPaddleDirection)dir;
+        if (!Enum.IsDefined(direction))
+            throw new HubException($"Invalid direction: {dir}!");
+        room.MovePaddle(Player, direction);
+        return Task.CompletedTask;
+    }
+
+    public Task LeaveRoom() {
+        Lobby.LeaveRoom(Player);
+        return Task.CompletedTask;
+    }
+
+    public Task RequestUsernameChange(string username) {
+        // TOOD: check this
+        Logger.LogInformation($"Player {Player} requested username change to [{username}]");
+        Player.Username = username;
+        return Task.CompletedTask;
+    }
+
+    public override Task OnDisconnectedAsync(Exception? exception) {
+        Lobby.RemovePlayer(Player);
+        return Task.CompletedTask;
+    }
+}

PongGame/Hubs/PongLobbyCollection.cs

@@ -0,0 +1,65 @@
+using System.Collections.Concurrent;
+using Microsoft.AspNetCore.SignalR;
+
+namespace PongGame.Hubs;
+
+public class PongLobby {
+    private readonly HashSet<PongPlayer> connectedPlayers = new();
+    private readonly Dictionary<string, PongRoom> PongRooms = new();
+
+    public PongLobby(ILogger<PongLobby> logger)
+        => Logger = logger;
+
+    public const int ROOM_ID_LENGTH = 4;
+
+    public PongPlayer CreatePlayer() {
+        var player = new PongPlayer();
+        lock (connectedPlayers)
+            connectedPlayers.Add(player);
+        return player;
+    }
+
+    public void RemovePlayer(PongPlayer player) {
+        if (player.ConnectedRoom is PongRoom room)
+            room.Leave(player);
+        lock (connectedPlayers)
+            _ = connectedPlayers.Remove(player);
+    }
+
+    public PongRoom CreateRoom(PongPlayer player) {
+        PongRoom room;
+        lock (PongRooms) {
+            room = new(GenerateRoomId(), Logger);
+            PongRooms.Add(room.ID, room);
+        }
+        room.Join(player);
+        return room;
+    }
+
+    public PongRoom JoinRoom(PongPlayer player, string roomId) {
+        PongRoom? room;
+        lock (PongRooms) {
+            room = PongRooms.GetValueOrDefault(roomId);
+        }
+        if (room is null) throw new HubException($"Room [{roomId}] not found!");
+        room.Join(player);
+        return room;
+    }
+
+    public void LeaveRoom(PongPlayer player) {
+        if (player.ConnectedRoom is PongRoom room)
+            room.Leave(player);
+    }
+
+    private readonly Random random = new();
+    private readonly ILogger<PongLobby> Logger;
+    private const string ALPHABET = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+
+    private string GenerateRoomId() {
+        string id;
+        do {
+            id = string.Concat(Enumerable.Range(0, ROOM_ID_LENGTH).Select(_ => ALPHABET[random.Next(ALPHABET.Length)]));
+        } while (PongRooms.ContainsKey(id));
+        return id;
+    }
+}

PongGame/Hubs/PongPaddleDirection.cs

@@ -0,0 +1,7 @@
+namespace PongGame;
+
+public enum PongPaddleDirection {
+    Up = -1,
+    Stop,
+    Down,
+}

PongGame/Hubs/PongPlayer.cs

@@ -0,0 +1,22 @@
+using System.Diagnostics;
+
+namespace PongGame.Hubs;
+
+[DebuggerDisplay($"{{{nameof(ToString)}(),nq}}")]
+public class PongPlayer {
+    private string username = default!;
+
+    public PongRoom? ConnectedRoom { get; internal set; }
+    public string Username {
+        get => username;
+        internal set {
+            if (username != value) {
+                username = value;
+                Task.Run(() => Client.UsernameChanged(value));
+            }
+        }
+    }
+    public IPongClient Client { get; internal set; } = default!;
+
+    public override string ToString() => $"[{Username}]";
+}

PongGame/Hubs/PongRoom.cs

@@ -0,0 +1,99 @@
+using System.ComponentModel;
+using Microsoft.AspNetCore.SignalR;
+
+namespace PongGame.Hubs;
+
+public class PongRoom {
+    public string ID { get; }
+    private readonly ILogger Logger;
+    private const string JOIN_LOG_TEMPLATE = "[{ID}] {Player} joined pong room as player {Number}!";
+    private const string LEAVE_LOG_TEMPLATE = "[{ID}] Player {Number} {Player} left pong room!";
+    private const string DIRECTION_LOG_TEMPLATE = "[{ID}] Player {Number} {player} moves paddle in direction: {direction}!";
+
+    public PongRoom(string id, ILogger logger) {
+        ID = id;
+        Logger = logger;
+        gameWorker.DoWork += GameLoop;
+    }
+
+    public PongPlayer? Player1 { get; private set; }
+    public PongPlayer? Player2 { get; private set; }
+    private PongGameState State = PongGameState.Initial;
+
+    public void Join(PongPlayer player) {
+        // TODO: synchronize this
+        if (Player1 is null) {
+            Player1 = player;
+            Logger.LogInformation(JOIN_LOG_TEMPLATE, ID, player, 1);
+        } else if (Player2 is null) {
+            Player2 = player;
+            Logger.LogInformation(JOIN_LOG_TEMPLATE, ID, player, 1);
+        } else
+            throw new HubException($"Lobby [{ID}] is already full!");
+        _ = Task.Run(PlayersChanged);
+        player.ConnectedRoom = this;
+    }
+
+    public void Leave(PongPlayer player) {
+        if (Player1 == player) {
+            Player1 = null;
+            Logger.LogInformation(LEAVE_LOG_TEMPLATE, ID, 1, player);
+        } else if (Player2 == player) {
+            Player2 = null;
+            Logger.LogInformation(LEAVE_LOG_TEMPLATE, ID, 2, player);
+        }
+        player.ConnectedRoom = null;
+        _ = Task.Run(PlayersChanged);
+    }
+
+    private BackgroundWorker gameWorker = new() {
+        WorkerSupportsCancellation = true
+    };
+
+    private void GameLoop(object? sender, DoWorkEventArgs e) {
+        while (!gameWorker.CancellationPending
+            && Player1 is PongPlayer p1
+            && Player2 is PongPlayer p2
+            && State.Status is GameStatus.InProgress) {
+            PongGameState.Update(ref State);
+            _ = Task.Run(() => Task.WhenAll(
+                p1.Client.ReceiveGameState(State),
+                p2.Client.ReceiveGameState(State)));
+            Thread.Sleep(1000 / 60);
+        }
+    }
+
+    private Task PlayersChanged() {
+        if (Player1 is PongPlayer player1 && Player2 is PongPlayer player2) {
+            Logger.LogInformation("[{ID}] Pong game started: {player1} vs. {player2}", ID, player1, player2);
+            ResumeGame();
+        } else if (Player1 is null && Player2 is null) {
+            CloseRoom();
+        } else
+            PauseGame();
+        return Task.CompletedTask;
+    }
+
+    private void ResumeGame() {
+        State.Status = GameStatus.InProgress;
+        if (!gameWorker.IsBusy) gameWorker.RunWorkerAsync();
+    }
+
+    private void PauseGame() => State.Status = GameStatus.Paused;
+    private void CloseRoom() => State.Status = GameStatus.Finished;
+
+    public override string ToString() => $"[{ID}]";
+
+    public void MovePaddle(PongPlayer player, PongPaddleDirection direction) {
+        if (Player1 == player) {
+            State.Paddle1.Direction = direction;
+            Logger.LogInformation(DIRECTION_LOG_TEMPLATE, ID, 1, player, direction);
+            return;
+        } else if (Player2 == player) {
+            State.Paddle2.Direction = direction;
+            Logger.LogInformation(DIRECTION_LOG_TEMPLATE, ID, 2, player, direction);
+            return;
+        }
+        throw new InvalidOperationException("Player is not in this room, but moved! Assumably players room wasn't deleted.");
+    }
+}

PongGame/Pages/Index.cshtml

@@ -6,4 +6,5 @@
 
 <div class="text-center">
     <h1 class="display-4">Welcome</h1>
+    <a asp-area="" asp-page="/Pong">Pong</a>
 </div>

PongGame/Pages/Index.cshtml.cs

@@ -9,7 +9,7 @@ public class IndexModel : PageModel {
         _logger = logger;
     }
 
-    public void OnGet() {
-
+    public IActionResult OnGet() {
+        return RedirectToPage("Pong");
     }
 }

PongGame/Pages/Pong.cshtml

@@ -0,0 +1,30 @@
+@page
+@model PongModel
+@{
+  ViewData["Title"] = "Pong";
+}
+
+<div class="text-center">
+  <h1 class="display-4">Pong</h1>
+  <h3 id="connection">Connection Status</h3>
+
+  <button id="createlobby" class="btn btn-primary mb-3">Create</button>
+  <button id="leavelobby" class="btn btn-primary mb-3">Leave</button>
+
+  <div class="input-group mb-3">
+    <input id="roomid" type="text" class="form-control" placeholder="Room ID" aria-label="Room ID" aria-describedby="joinroom">
+    <button id="joinroom" class="btn btn-outline-secondary" type="button">Button</button>
+  </div>
+
+  <div class="input-group mb-3">
+    <input id="username" type="text" class="form-control" placeholder="Username" aria-label="Username" aria-describedby="setusername">
+    <button id="setusername" class="btn btn-outline-secondary" type="button">Set Username</button>
+  </div>
+
+  <div id="canvas-container" class="mb-3"></div>
+</div>
+
+<script src="~/lib/signalr/dist/browser/signalr.min.js"></script>
+<script src="~/lib/signalr/dist/browser/signalr-protocol-msgpack.min.js"></script>
+<script src="~/lib/pixi/dist/pixi.min.js"></script>
+<script src="~/js/pong.js"></script>

PongGame/Pages/Pong.cshtml.cs

@@ -0,0 +1,15 @@
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.Mvc.RazorPages;
+
+namespace PongGame.Pages;
+public class PongModel : PageModel {
+    private readonly ILogger<PongModel> _logger;
+
+    public PongModel(ILogger<PongModel> logger) {
+        _logger = logger;
+    }
+
+    public void OnGet() {
+
+    }
+}

PongGame/PongGame.csproj

@@ -8,6 +8,7 @@
   </PropertyGroup>
 
   <ItemGroup>
+    <PackageReference Include="Microsoft.AspNetCore.SignalR.Protocols.MessagePack" Version="6.0.10" />
     <PackageReference Include="Microsoft.VisualStudio.Azure.Containers.Tools.Targets" Version="1.17.0" />
   </ItemGroup>
 

PongGame/Program.cs

@@ -1,7 +1,14 @@
+using MessagePack;
+using PongGame.Hubs;
+
 var builder = WebApplication.CreateBuilder(args);
 
 // Add services to the container.
 builder.Services.AddRazorPages();
+builder.Services.AddSingleton<PongLobby>(services
+    => new(services.GetRequiredService<ILogger<PongLobby>>()));
+builder.Services.AddSignalR()
+    .AddMessagePackProtocol();
 
 var app = builder.Build();
 
@@ -15,6 +22,9 @@ app.UseRouting();
 
 app.UseAuthorization();
 
-app.MapRazorPages();
+app.UseEndpoints(endpoints => {
+    endpoints.MapRazorPages();
+    endpoints.MapHub<PongHub>("/pong/hub");
+});
 
 app.Run();

PongGame/libman.json

@@ -0,0 +1,37 @@
+{
+  "version": "1.0",
+  "defaultProvider": "jsdelivr",
+  "libraries": [
+    {
+      "library": "@microsoft/signalr-protocol-msgpack@6.0.10",
+      "destination": "wwwroot/lib/signalr/",
+      "files": [
+        "dist/browser/signalr-protocol-msgpack.js",
+        "dist/browser/signalr-protocol-msgpack.js.map",
+        "dist/browser/signalr-protocol-msgpack.min.js",
+        "dist/browser/signalr-protocol-msgpack.min.js.map"
+      ]
+    },
+    {
+      "library": "@microsoft/signalr@6.0.10",
+      "destination": "wwwroot/lib/signalr/",
+      "files": [
+        "dist/browser/signalr.js",
+        "dist/browser/signalr.js.map",
+        "dist/browser/signalr.min.js",
+        "dist/browser/signalr.min.js.map"
+      ]
+    },
+    {
+      "provider": "jsdelivr",
+      "library": "pixi.js@7.0.2",
+      "destination": "wwwroot/lib/pixi/",
+      "files": [
+        "dist/pixi.js",
+        "dist/pixi.js.map",
+        "dist/pixi.min.js.map",
+        "dist/pixi.min.js"
+      ]
+    }
+  ]
+}

PongGame/wwwroot/js/pong.js

@@ -0,0 +1,169 @@
+"use strict";
+
+const connection = new signalR.HubConnectionBuilder()
+  .withUrl("/pong/hub")
+  .withAutomaticReconnect()
+  .withHubProtocol(new signalR.protocols.msgpack.MessagePackHubProtocol())
+  .build();
+
+function getElement(id) {
+  return document.getElementById(id) ?? console.error(`Element #${id} not found!`)
+}
+
+const connectionStatus = getElement("connection");
+const createlobby = getElement("createlobby");
+const roomidinput = getElement("roomid");
+const joinroom = getElement("joinroom");
+const usernameinput = getElement("username");
+const setusername = getElement("setusername");
+const leavelobby = getElement("leavelobby");
+
+connection.onclose(function (error) {
+  if (error) {
+    connectionStatus.textContent = "Unexpected error!";
+    return console.error(`Connection aborted: ${error.message}`);
+  }
+  console.info("Disconnected!");
+  connectionStatus.textContent = "Closed!";
+});
+
+connection.onreconnecting(function (error) {
+  if (error) {
+    connectionStatus.textContent = "Reconnecting!";
+    return console.error(`Connection reconnecting: ${error.message}`);
+  }
+  console.info("Reconnecting!");
+  connectionStatus.textContent = "Reconnecting!";
+});
+
+connection.onreconnected(function (connectionId) {
+  console.info(`Connected as ${connectionId}!`);
+  connectionStatus.textContent = "Connected!";
+});
+
+createlobby.addEventListener("click", function (event) {
+  connection.invoke("CreateRoom").then(function (roomId) {
+    roomidinput.value = roomId;
+    console.info(`Joined room [${roomId}]`);
+  }).catch(function (err) {
+    return console.error(err.toString());
+  });
+  event.preventDefault();
+});
+
+connection.on("GameStateChanged", function (state) {
+  console.info(`Game is now in state ${state}`);
+});
+connection.on("UsernameChanged", function (username) {
+  console.info(`Username is now ${username}`);
+  usernameinput.value = username;
+});
+
+joinroom.addEventListener("click", function (event) {
+  connection.invoke("JoinRoom", roomidinput.value).catch(function (err) {
+    return console.error(err.toString());
+  });
+  event.preventDefault();
+});
+
+setusername.addEventListener("click", function (event) {
+  connection.invoke("RequestUsernameChange", usernameinput.value).catch(function (err) {
+    return console.error(err.toString());
+  });
+  event.preventDefault();
+});
+
+leavelobby.addEventListener("click", function (event) {
+  connection.invoke("LeaveRoom").catch(function (err) {
+    return console.error(err.toString());
+  });
+  event.preventDefault();
+});
+
+function movePaddle(direction) {
+  connection.invoke("MovePaddle", direction).catch(function (err) {
+    return console.error(err.toString());
+  });
+}
+
+function moveUp() { return movePaddle(-1); }
+function stopPaddle() { return movePaddle(0); }
+function moveDown() { return movePaddle(1); }
+
+// Create the application helper and add its render target to the page
+let app = new PIXI.Application({ width: 1000, height: 500 });
+getElement('canvas-container').appendChild(app.view);
+
+let graphics = new PIXI.Graphics();
+app.stage.addChild(graphics);
+
+function renderPaddle(graphics, state, xMid) {
+  var xLeft = xMid - 5;
+  graphics.beginFill(0x00FFFF);
+  graphics.drawRect(xLeft, state.Height - 25, 10, 50);
+  graphics.endFill();
+}
+
+function renderBall(graphics, state) {
+  graphics.beginFill(0xFF00FF);
+  graphics.drawCircle(state.Pos.X, state.Pos.Y, 4);
+  graphics.endFill();
+}
+
+function renderGameState(graphics, state) {
+  graphics.clear();
+  renderPaddle(graphics, state.Paddle1, 50);
+  renderPaddle(graphics, state.Paddle2, 1000 - 50);
+  renderBall(graphics, state.BallState);
+}
+
+connection.on("ReceiveGameState", function (state) {
+  renderGameState(graphics, state);
+});
+
+const keyEvent = (function () {
+  var upPressed = false;
+  var downPressed = false;
+
+  function moveUpdated() {
+    if (upPressed == downPressed) stopPaddle();
+    else if (upPressed) moveUp();
+    else if (downPressed) moveDown();
+    else console.error("unknown move!");
+  }
+
+  function handler(event) {
+    if (event.repeat) return;
+    if (event.path.indexOf(document.body) != 0) return; // only use key if it was pressed on empty space
+    var pressed = event.type == "keyup";
+    // W Key is 87, Up arrow is 87
+    // S Key is 83, Down arrow is 40
+    switch (event.keyCode) {
+      case 87:
+      case 38:
+        upPressed = pressed;
+        break;
+      case 83:
+      case 40:
+        downPressed = pressed;
+        break;
+      default: return;
+    }
+
+    event.preventDefault();
+    moveUpdated();
+  }
+
+  return handler;
+})();
+
+document.addEventListener('keydown', keyEvent);
+document.addEventListener('keyup', keyEvent);
+
+connection.start().then(function () {
+  console.info(`Connected!`);
+  connectionStatus.textContent = "Connected!";
+}).catch(function (err) {
+  connectionStatus.textContent = "Connection failed!";
+  return console.error(err.toString());
+});

package-lock.json

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package.json

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+{
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+  }
+}