Application.js

import EventEmitter from "./EventEmitter";
import Session from "./Session";

export default class Application extends EventEmitter {
  constructor(io) {
    super();
    
    this.io = io;
    this.slots = [];
    
    io.on("connect", (socket) => {
      this.appendSocket(socket);
    });
  }
  
  numberOfSessions() {
    return this.slots.reduce((counter, session) => {
      return counter + (session ? 1 : 0);
    }, 0);
  }
  
  appendSocket(socket) {
    let session = new Session(socket);
    
    socket.on("disconnect", () => {
      let index = this.slots.indexOf(session);
      if (index !== -1) {
        this.slots[index] = null;
        session.dispose();
      }
    });
    
    socket.on("dispatch", (payload = {}) => {
      payload.session = session;
      this.dispatch(payload);
    });
    
    let index = this.slots.indexOf(null);
    if (index !== -1) {
      this.slots[index] = session;
    } else {
      this.slots.push(session);
    }
  }
  
  dispatch(payload = {}) {
    this.emit("dispatch", payload);
  }
}

subote-usage.js

import http from "http";
import path from "path";
import express from "express";
import socketio from "socket.io";
import MyApplication from "./app/MyApplication";

let app = express();
let server = http.createServer(app);
let io = socketio(server);

app.use(express.static(path.join(__dirname, "../../public")));

server.listen(config.SERVER_PORT, () => {
  console.log("Listening on port %d", server.address().port);
});

new MyApplication(io).run();