| const SCROLL_UP = 'up'; |
| const SCROLL_DOWN = 'down'; |
|
|
| import { useState, useEffect } from 'react'; |
|
|
| const useScrollDirection = ({ initialDirection, thresholdPixels, off } = {}) => { |
| const [scrollDir, setScrollDir] = useState(initialDirection); |
|
|
| useEffect(() => { |
| const threshold = thresholdPixels || 0; |
| let lastScrollY = window.pageYOffset; |
| let ticking = false; |
|
|
| const updateScrollDir = () => { |
| const scrollY = window.pageYOffset; |
|
|
| if (Math.abs(scrollY - lastScrollY) < threshold) { |
| |
| ticking = false; |
| return; |
| } |
|
|
| setScrollDir(scrollY > lastScrollY ? SCROLL_DOWN : SCROLL_UP); |
| lastScrollY = scrollY > 0 ? scrollY : 0; |
| ticking = false; |
| }; |
|
|
| const onScroll = () => { |
| if (!ticking) { |
| window.requestAnimationFrame(updateScrollDir); |
| ticking = true; |
| } |
| }; |
|
|
| |
| |
| |
| |
| !off ? window.addEventListener('scroll', onScroll) : setScrollDir(initialDirection); |
|
|
| return () => window.removeEventListener('scroll', onScroll); |
| }, [initialDirection, thresholdPixels, off]); |
|
|
| return scrollDir; |
| }; |
|
|
| export default useScrollDirection; |
|
|
