chatServer.js

var socketIO = require("socket.io");
var verify = require("./routes/verify");

module.exports = function (httpServer) {
    var io = socketIO(httpServer);

    io.use(function (socket, next) {
        var token = socket.request._query.token;
        var auth = verify.verifyOrdinaryUser(token);
        if (!auth.success) {
            //could not verify user's identity
            console.log(auth.error);
            socket.disconnect();
            return;
        }
        var username = auth.user._doc.username;
        socket.username = username;
        next();
    });

    io.on("connection", function (socket) {
        var username = socket.username;
        console.log('a user connected: ' + username);

        /*
            io.sockets.sockets becomes an object of Sockets with ID as the key
        */

        var keys = Object.keys(io.sockets.sockets);//get an array of socket ID as Key
        var onlineUsers = new Array(keys.length);
        keys.forEach(function (idKey, i) {
            var username = io.sockets.sockets[idKey].username;
            onlineUsers[i] = username;
        });

        socket.emit("online users", JSON.stringify(onlineUsers));
        socket.broadcast.emit("new user", username);

        socket.on('disconnect', function () {
            console.log('user disconnected: ' + this.username);
            io.emit("user left", this.username);
        });

        socket.on("disconnect message", function () {
            socket.disconnect();

        });

        socket.on("chat message", function (msg) {
            //sends message to all chat users except for the sender of the message
            socket.broadcast.emit("chat message", this.username + " said: " + msg);
        });

    });

    process.on('SIGINT', function () {
        console.log("closing chat server");
        io.close();
    });
}