KITFORMA · EDITORIAL GUIDE
Why does a React subscription connect twice in development?
KitForma editorial guide. When StrictMode exercises an Effect, setup can be followed by cleanup and setup again.
Step-by-step guidance
When StrictMode exercises an Effect, setup can be followed by cleanup and setup again. Pair each subscription with its own unsubscribe function:
useEffect(() => subscribe(roomId), [roomId]) works when subscribe returns cleanup. Keep purchases and other user-triggered writes in event handlers. Verify that mounting, changing rooms and unmounting leave one active subscription, then zero; counting console messages alone does not establish a leak.Sources and verification
Sources checked:
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