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Custom React Hook for setting a passive scroll listener and get updated scrollY and scroll direction information
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| /** | |
| * useScrollListener hook | |
| * Usage: const { scrollY, scrollDirection } = useScrollListener(); | |
| */ | |
| import { useReducer, useEffect } from 'react'; | |
| function reducer(state, action) { | |
| switch (action.type) { | |
| case 'set': | |
| return { | |
| scrollY: action.payload.scrollY, | |
| scrollDirection: action.payload.scrollY > state.scrollY ? 'down' : 'up' | |
| }; | |
| } | |
| } | |
| export function useScrollListener() { | |
| const [state, dispatch] = useReducer(reducer, { | |
| scrollY: 0, | |
| scrollDirection: 'down' | |
| }); | |
| function listener() { | |
| const scrollTop = | |
| document.documentElement.scrollTop || document.body.scrollTop; | |
| dispatch({ | |
| type: 'set', | |
| payload: { | |
| scrollY: scrollTop | |
| } | |
| }); | |
| } | |
| useEffect(() => { | |
| window.addEventListener('scroll', listener, false); | |
| return () => { | |
| window.removeEventListener('scroll', listener, false); | |
| }; | |
| }, []); | |
| return { | |
| ...state | |
| }; | |
| } |
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