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Dylan Johnston d-johnston

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d-johnston / useFocusEffect example.ts

Created June 12, 2025 18:19

React Navigation (for React Native) showing their useFocusEffect which stops a counting mechanism when the page focus is lost


	const [count, setCount] = useState(0)
	const [slowCount, setSlowCount] = useState(0)
	const [isToggled, setIsToggled] = useState(false)

	useFocusEffect(
	useCallback(() => {
	console.log('slowCount useEffect ran')
	const interval = setInterval(() => {
	console.log('slow count incremented')

d-johnston / effect snippet.ts

Created June 12, 2025 18:12

Example of how useEffects still run when you switch away from a screen


	const [count, setCount] = useState(0)
	const [slowCount, setSlowCount] = useState(0)
	const [isToggled, setIsToggled] = useState(false)

	useEffect(() => {
	console.log('slowCount useEffect ran')
	const interval = setInterval(() => {
	console.log('slow count incremented')
	setSlowCount((prevState) => prevState + 1)