Does Socket.io automatically reconnect?
Yes, by default. Socket.io reconnects with configurable options: reconnectionAttempts (max attempts), reconnectionDelay (initial delay), reconnectionDelayMax (max delay), and randomizationFactor. Reconnection uses exponential backoff. Some disconnect reasons (io server disconnect, io client disconnect) don't trigger reconnection.
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More FAQs in Socket.io Error Handling and Reconnection Reliable Real-Time Communication
Store active chat target user IDs in a client-side array. On the 'connect' event (which fires on reconnection too), re-emit 'join:chat' for each stored target. The server rejoins the socket to the room. This restores room membership after the new socket ID is assigned.
Acknowledgments are callback functions passed as the last argument to socket.emit(). The server calls the callback with a response, confirming the event was received and processed. Use them for important events like message sending: socket.emit('message:send', data, (response) => { ... }).
Maintain a client-side message queue. When disconnected, push messages to the queue. On reconnect, send all queued messages via socket.emit() with acknowledgments. If an acknowledgment fails, re-queue the message. This ensures messages aren't lost during disconnections.
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