63 lines
1.8 KiB
Markdown
63 lines
1.8 KiB
Markdown
---
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title: Do Not Put Effect Events in Dependency Arrays
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impact: LOW
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impactDescription: avoids unnecessary effect re-runs and lint errors
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tags: advanced, hooks, useEffectEvent, dependencies, effects
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---
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## Do Not Put Effect Events in Dependency Arrays
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Effect Event functions do not have a stable identity. Their identity intentionally changes on every render. Do not include the function returned by `useEffectEvent` in a `useEffect` dependency array. Keep the actual reactive values as dependencies and call the Effect Event from inside the effect body or subscriptions created by that effect.
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**Incorrect (Effect Event added as a dependency):**
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```tsx
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import { useEffect, useEffectEvent } from 'react';
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function ChatRoom({
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roomId,
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onConnected,
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}: {
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roomId: string;
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onConnected: () => void;
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}) {
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const handleConnected = useEffectEvent(onConnected);
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useEffect(() => {
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const connection = createConnection(roomId);
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connection.on('connected', handleConnected);
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connection.connect();
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return () => connection.disconnect();
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}, [roomId, handleConnected]);
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}
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```
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Including the Effect Event in dependencies makes the effect re-run every render and triggers the React Hooks lint rule.
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**Correct (depend on reactive values, not the Effect Event):**
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```tsx
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import { useEffect, useEffectEvent } from 'react';
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function ChatRoom({
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roomId,
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onConnected,
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}: {
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roomId: string;
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onConnected: () => void;
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}) {
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const handleConnected = useEffectEvent(onConnected);
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useEffect(() => {
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const connection = createConnection(roomId);
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connection.on('connected', handleConnected);
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connection.connect();
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return () => connection.disconnect();
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}, [roomId]);
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}
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```
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Reference: [React useEffectEvent: Effect Event in deps](https://react.dev/reference/react/useEffectEvent#effect-event-in-deps)
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