Chatly is a small real-time chat application built with Socket.io in the winter of 2020. It started as a task for a computer science course and became my first hands-on experience with WebSockets and event-driven servers.
What it does
- Rooms. You enter a display name and a room; everyone in the same room sees each other’s messages, and the room gets a notice when someone joins or leaves.
- Live user list per room, updated as people come and go.
- Location sharing. One click sends your coordinates as a Google Maps link to the room.
- Profanity filter on outgoing messages.
How it is built
The server is Express serving static files plus a Socket.io server. A small utils/ module tracks users per room and generates timestamped message objects. Events are join, sendMessage, sendLocation and disconnect, each with an acknowledgement callback so the client knows whether the action succeeded. The front end is plain JavaScript rendering templates into the page.
What I learned
Socket.io’s model of rooms, broadcasts and acknowledgements gave me a mental model for real-time systems that carried through to the WebSocket-based direct messaging I later worked on professionally. The user-tracking module also taught a simple lesson: keep the in-memory state in one place with a tiny API, and everything else stays simple.
Source in the repository.