log disconnects, emit user left events, add perMessageDeflate option

src/index.ts

@@ -36,7 +36,8 @@ const io = socketIO(server, {
 
         res.writeHead(200, headers);
         res.end();
-    }
+    },
+    perMessageDeflate: true
 });
 
 // listens on host:9090/metrics
@@ -83,13 +84,20 @@ io.on('connection', socket => {
         for (const roomID of Object.keys(socket.rooms)) {
             const clients = Object.keys(rooms[roomID].sockets).filter(id => id !== socket.id);
 
+            if (roomID !== socket.id) {
+                socket.to(roomID).emit('user has left', socket.id);
+            }
+
             if (clients.length > 0) {
                 socket.broadcast.to(roomID).emit('room-user-change', clients);
             }
         }
     });
 
-    socket.on('disconnect', () => {
+    socket.on('disconnect', reason => {
+        serverDebug(
+            `${socket.id} was disconnected from url ${socket.conn.request.url} for the following reason: ${reason}`
+        );
         socket.removeAllListeners();
     });
 });