fix: cleanup event-emitter subscriptions in provider hooks#392
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fix: cleanup event-emitter subscriptions in provider hooks#392
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Zaimwa9
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kyle-ssg and
talissoncosta
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kyle-ssg
talissoncosta
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Apr 20, 2026
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talissoncosta
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Looks good, just one question. Not blocking
| useEffect(() => { | ||
| if (!flagsmith) return | ||
| setRenderRef(getRenderKey(flagsmith, flags, traits)) | ||
| const unsubscribe = events.on('event', () => { |
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Quick question: was the switch from events.once => events.on intentional?
Just want to make sure you're aware it's a behavior change: in the old code each render re-registered a once listener (because useRef's arg evaluates every render), so the hook reacted on every emit incidentally.
With events.on, it's a single persistent subscription. Same net behavior for consumers as far as I can tell, but wanted to flag it in case you hadn't spotted it.
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docs/if required so people know about the feature.Changes
Closes #390
Hooks were rendering at render time instead than in an effect and the cleanup paths did not remove all registered listeners
useFlagsmithLoadinganduseFlags: subscribe inside useEffect with emitter.on's returned unsubscribe as cleanup. Removes render-time events.on and multi subscriptionHow did you test this code?
main(pre-fix)useFlagsmithLoading, one fromuseFlags)fix/react-subscription-leak