| | 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; |
| |
|