Added private messaing (Billmike#7)

To use, click the user's name in the user list, then type your message and send it.

Changes made internally:
The connections is now an object rather than an array. To retrieve a connection, use connections[username].

index.html

@@ -45,13 +45,14 @@ <h3>Online Users</h3>
                             <label>Enter Message:</label>
                             <textarea class="form-control" id="message"></textarea>
                             <br>
-                            <input type="submit" class="btn btn-primary" value="Send message">
+                            <input type="submit" class="btn btn-primary" id="send-btn" value="Send message">
                         </div>
                     </form>
                 </div>
             </div>
         </div>
     <script>
+        var messaging = undefined;
         $(function(){
             var socket = io.connect();
             var $messageForm = $('#messageForm');
@@ -65,13 +66,27 @@ <h3>Online Users</h3>
 
             $messageForm.submit((e) => {
                 e.preventDefault();
-                socket.emit('send message', $message.val());
+                if(messaging == undefined){
+                  socket.emit('send message', $message.val());
+                }else{
+                  socket.emit('private message', [messaging, $message.val()]);
+                  $chat.append('<div class="well"><strong>[you -> ' + messaging + ']' + ': </strong><i>' + $message.val());
+                  messaging = undefined;
+                  $('#send-btn')[0].value = "Send message";
+                }
                 $message.val('');
             });
 
             socket.on('new message', (data) => {
                 $chat.append('<div class="well"> <strong> ' + data.user + '</strong>: ' + data.msg + '</div>')
             });
+            socket.on('private message', (data) => {
+              $chat.append('<div class="well"><strong>[' + data[0] + ' -> you]' + ': </strong><i>' + data[1]);
+            })
+            socket.on('error-msg', (data) => {
+              console.log("Error! " + data);
+              $chat.append('<div class="well"><strong style="color:red">Error! ' + data + '</strong>');
+            })
 
             $userForm.submit((e) => {
                 e.preventDefault();
@@ -87,11 +102,15 @@ <h3>Online Users</h3>
             socket.on('get users',  (data) => {
                 var html = '';
                 for (i = 0; i < data.length; i++){
-                    html += '<li class="list-group-items">'+ data[i] + '</li>';
+                    html += '<li class="list-group-items"><a href="#" onclick="message(\'' + data[i] + '\')">'+ data[i] + '</a></li>';
                 }
                 $users.html(html);
             })
         });
+        function message(user){
+            messaging = user;
+            $('#send-btn')[0].value = "Send private message (" + user + ")";
+        }
     </script>
     </body>
-</html>
+</html>

server.js

@@ -3,6 +3,7 @@ const app = express();
 const server = require('http').createServer(app);
 const io = require('socket.io').listen(server);
 
+var connections = {};
 users = [];
 connections = [];
 
@@ -12,16 +13,16 @@ console.log('Server is presently running....');
 
 app.get('/', (req, res) => res.sendFile(__dirname + '/index.html'));
 
+
 io.sockets.on('connection', (socket) => {
-    connections.push(socket);
     console.log('Connected: %s connection(s) currently active.', connections.length);
 
     // Disconnect
     socket.on('disconnect', (data) => {
         if (!socket.username) return;
-        users.splice(users.indexOf(socket.username), 1);
+        delete connections[socket.username];
         updateUsername();
-        connections.splice(connections.indexOf(socket), 1);
+        delete users[socket.username];
         console.log('Disconnected: %s connection(s) currently active.', connections.length);
     });
     // Message
@@ -34,9 +35,20 @@ io.sockets.on('connection', (socket) => {
         callback(true);
         socket.username = data;
         users.push(socket.username);
+        connections[socket.username] = socket;
         updateUsername();
     });
 
+    socket.on('private message', (data) => {
+      var user = data[0];
+      var message = data[1];
+      if(user in connections){
+        connections[user].emit("private message", [user, message]);
+      }else{
+        socket.emit("error-msg", "User " + user + " does not exist!");
+      }
+    })
+
     function updateUsername() {
         io.sockets.emit('get users', users);
     }