56 lines
1.5 KiB
Markdown
56 lines
1.5 KiB
Markdown
---
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title: Store Event Handlers in Refs
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impact: LOW
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impactDescription: stable subscriptions
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tags: advanced, hooks, refs, event-handlers, optimization
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---
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## Store Event Handlers in Refs
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Store callbacks in refs when used in effects that shouldn't re-subscribe on callback changes.
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**Incorrect (re-subscribes on every render):**
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```tsx
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function useWindowEvent(event: string, handler: (e) => void) {
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useEffect(() => {
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window.addEventListener(event, handler);
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return () => window.removeEventListener(event, handler);
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}, [event, handler]);
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}
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```
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**Correct (stable subscription):**
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```tsx
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function useWindowEvent(event: string, handler: (e) => void) {
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const handlerRef = useRef(handler);
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useEffect(() => {
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handlerRef.current = handler;
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}, [handler]);
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useEffect(() => {
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const listener = (e) => handlerRef.current(e);
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window.addEventListener(event, listener);
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return () => window.removeEventListener(event, listener);
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}, [event]);
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}
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```
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**Alternative: use `useEffectEvent` if you're on latest React:**
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```tsx
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import { useEffectEvent } from "react";
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function useWindowEvent(event: string, handler: (e) => void) {
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const onEvent = useEffectEvent(handler);
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useEffect(() => {
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window.addEventListener(event, onEvent);
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return () => window.removeEventListener(event, onEvent);
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}, [event]);
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}
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```
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`useEffectEvent` provides a cleaner API for the same pattern: it creates a stable function reference that always calls the latest version of the handler.
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