public/js/index.js

@@ -10,6 +10,7 @@ document.getElementById('ok').addEventListener('click', function () {
     username = document.getElementById('username').value;
     room_name = document.getElementById('room').value;
 
+    if (username !== "" && room_name !== "") {
         socket = io("/", {
             closeOnBeforeunload: false
         });
@@ -51,6 +52,9 @@ document.getElementById('ok').addEventListener('click', function () {
         socket.on('user left', function (data) {
             addLogMessage(data + ' left');
         });
+    } else {
+        document.getElementById('error').innerText = 'Username and/or room name cannot be empty!';
+    }
 });
 
 function open_manual() {