How was the typing indicator implemented?

The typing indicator is usually implemented using real-time events between clients and the server.

Example implementation:

1. When a user starts typing, the client sends a "user_typing" event to the server (via WebSocket or another protocol).
2. The server broadcasts this event to other chat participants.
3. Clients receiving the event display the "User is typing..." indicator.
4. When the user stops typing (via a timeout or a "stop_typing" event), the corresponding event is sent, and the indicator is hidden.

Example in JavaScript using WebSocket:

// Client
let typingTimeout;
inputField.addEventListener('input', () => {
  socket.send(JSON.stringify({ type: 'user_typing', userId }));
  clearTimeout(typingTimeout);
  typingTimeout = setTimeout(() => {
    socket.send(JSON.stringify({ type: 'stop_typing', userId }));
  }, 3000); // 3 seconds after the last input
});

// Server broadcasts events to other clients

Thus, the indicator works based on start and stop typing events transmitted in real-time.