effect/no-event-handler

Disallow using state and an effect as an event handler.

• Category: State & Effects
• Severity: warn
• Source: eslint-plugin-react-you-might-not-need-an-effect
• Framework: global
• Enabled when: eslint-plugin-react-you-might-not-need-an-effect installed in project
• Documentation: https://react.dev/learn/you-might-not-need-an-effect#sharing-logic-between-event-handlers

Validation prompt

Use this to decide whether a fired diagnostic is real or a false positive.

Fires on a cleanup-less useEffect containing an if statement with no else whose test reads state (avoidEventHandler) or a prop (avoidPropHandler) — the textbook 'when X becomes truthy, do the side effect' pattern that belongs in the handler that flipped X. False positive: the state being checked is set by an external subscription (storage event, IntersectionObserver) the handler cannot observe.

Fix prompt

Use this once validation confirms the diagnostic is real.

Move the work into the event handler that sets the state (onClick, onSubmit, onChange) and call it directly — no intermediate state hop. If multiple handlers share the work, extract a regular function and call it from each; do not route through useEffect. For prop-callback variants (onSomething from props), invoke the callback from the parent's handler instead. See https://react.dev/learn/you-might-not-need-an-effect#sharing-logic-between-event-handlers

Related rules

More State & Effects rules from the rules reference:

• effect/no-initialize-state: Disallow initializing state in an effect.
• effect/no-pass-data-to-parent: Disallow passing data to parents in an effect.
• effect/no-pass-live-state-to-parent: Disallow passing live state to parents in an effect.
• effect/no-reset-all-state-on-prop-change: Disallow resetting all state in an effect when a prop changes.
• react-doctor/activity-wraps-effect-heavy-subtree: Audit the `<Activity>` subtree: every hide/show cycle tears down and recreates every `useEffect`/`useLayoutEffect` inside, so move subscriptions and effect-driven setState chains outside the boundary or pre-resolve the data above it.