express: app
});
+class TicTacToe {
+ constructor() {
+ this.moves = [];
+ this.board = Array(9).fill(null);
+ this.clients = [];
+ this.next_client_id = 1;
+ }
+
+ /* Returns Boolean indicating whether move was legal and added. */
+ add_move(square) {
+ /* Cannot move to an occupied square. */
+ if (this.board[square])
+ return false;
+
+ this.board[square] = 'X';
+ this.moves.push(square);
+
+ return true;
+ }
+
+ add_client(response) {
+ const id = this.next_client_id;
+ this.clients.push({id: id,
+ response: response});
+ this.next_client_id++;
+
+ return id;
+ }
+
+ remove_client(id) {
+ this.clients = this.clients.filter(client => client.id !== id);
+ }
+
+ /* Send a string to all clients */
+ broadcast_string(str) {
+ this.clients.forEach(client => client.response.write(str + '\n'));
+ }
+
+ /* Send an event to all clients.
+ *
+ * An event has both a declared type and a separate data block.
+ * It also ends with two newlines (to mark the end of the event).
+ */
+ broadcast_event(type, data) {
+ this.broadcast_string(`event: ${type}\ndata: ${data}\n`);
+ }
+
+ broadcast_move(square) {
+ this.broadcast_event("move", square);
+ }
+}
+
app.get('/', (request, response) => {
const game = request.game;
response.render('tictactoe-game.html');
});
+app.post('/move', (request, response) => {
+ const game = request.game;
+ const square = request.body.square;
+
+ const legal = game.add_move(square);
+
+ /* Inform this client whether the move was legal. */
+ response.send(JSON.stringify(legal));
+
+ /* And only if legal, inform all clients. */
+ if (! legal)
+ return;
+
+ game.broadcast_move(square);
+});
+
+app.get('/events', (request, response) => {
+ const game = request.game;
+
+ /* These headers will keep the connection open so we can stream events. */
+ const headers = {
+ "Content-type": "text/event-stream",
+ "Connection": "keep-alive",
+ "Cache-Control": "no-cache"
+ };
+ response.writeHead(200, headers);
+
+ /* Add this new client to our list of clients. */
+ const id = game.add_client(response);
+
+ /* And queue up cleanup to be triggered on client close. */
+ request.on('close', () => {
+ game.remove_client(id);
+ });
+});
+
exports.app = app;
+exports.name = "tictactoe";
+exports.Game = TicTacToe;