Setting the file. One moment.
Skill 03 · Vercel React Best Practices
Subchapter 3.6
rules/advanced-effect-event-deps.mdMarkdown2 KBView on GitHub
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.
Incorrect (Effect Event added as a dependency):
import { useEffect, useEffectEvent } from 'react'
function ChatRoom({ roomId, onConnected }: {
roomId: string
onConnected: () => void
}) {
const handleConnected = useEffectEvent(onConnected)
useEffect(() => {
const connection = createConnection(roomId)
connection.on('connected', handleConnected)
connection.connect()
return () => connection.disconnect()
}, [roomId, handleConnected])
}Including the Effect Event in dependencies makes the effect re-run every render and triggers the React Hooks lint rule.
Correct (depend on reactive values, not the Effect Event):
import { useEffect, useEffectEvent } from 'react'
function ChatRoom({ roomId, onConnected }: {
roomId: string
onConnected: () => void
}) {
const handleConnected = useEffectEvent(onConnected)
useEffect(() => {
const connection = createConnection(roomId)
connection.on('connected', handleConnected)
connection.connect()
return () => connection.disconnect()
}, [roomId])
}