advanced-event-handler-refs

title: Store Event Handlers in Refs
impact: LOW
impactDescription: stable subscriptions
tags: advanced, hooks, refs, event-handlers, optimization

Store Event Handlers in Refs

Store callbacks in refs when used in effects that shouldn't re-subscribe on callback changes.

**Incorrect (re-subscribes on every render):**

function useWindowEvent(event: string, handler: (e: Event) => void) {
  useEffect(() => {
    window.addEventListener(event, handler)
    return () => window.removeEventListener(event, handler)
  }, [event, handler])
}

**Correct (stable subscription):**

function useWindowEvent(event: string, handler: (e: Event) => void) {
  const handlerRef = useRef(handler)
  useEffect(() => {
    handlerRef.current = handler
  }, [handler])

  useEffect(() => {
    const listener = (e: Event) => handlerRef.current(e)
    window.addEventListener(event, listener)
    return () => window.removeEventListener(event, listener)
  }, [event])
}

**Alternative: use `useEffectEvent` if you're on latest React:**

import { useEffectEvent } from 'react'

function useWindowEvent(event: string, handler: () => void) {
  const onEvent = useEffectEvent(handler)

  useEffect(() => {
    window.addEventListener(event, onEvent)
    return () => window.removeEventListener(event, onEvent)
  }, [event])
}

`useEffectEvent` provides a cleaner API for the same pattern: it creates a stable function reference that always calls the latest version of the handler.