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import { raf } from '@react-spring/rafz'
import { useRef, useState } from 'react'
import { useIsomorphicLayoutEffect } from './useIsomorphicEffect'
type SCROLL_UP = 'up'
type SCROLL_DOWN = 'down'
export type SCROLL_DIR = SCROLL_DOWN | SCROLL_UP
type UseWindowScrolling = (args: {
threshold?: number | [down: number, up: number]
active?: boolean
yOffset?: number
onScroll?: (e: Event) => void
}) => [direction: SCROLL_DIR | undefined, scrollTop: number]
export const useWindowScrolling: UseWindowScrolling = ({
active = true,
threshold = 0,
yOffset = 0,
onScroll,
}) => {
const [direction, setDirection] = useState<SCROLL_DIR | undefined>(undefined)
const [scrollTop, setScrollTop] = useState(0)
const lastScrollY = useRef(0)
const ticking = useRef(false)
useIsomorphicLayoutEffect(() => {
const updateScrollDir = () => {
const scrollY = window.pageYOffset
const direction = scrollY > lastScrollY.current ? 'down' : 'up'
const thresholdValue = Array.isArray(threshold)
? threshold[direction === 'down' ? 0 : 1]
: threshold
if (!active) {
setDirection(undefined)
return
}
if (scrollY < yOffset) {
ticking.current = false
return
}
if (Math.abs(scrollY - lastScrollY.current) < thresholdValue) {
ticking.current = false
return
}
lastScrollY.current = scrollY > 0 ? scrollY : 0
ticking.current = false
setDirection(direction)
setScrollTop(scrollY)
}
const handleScroll = (e?: Event) => {
if (!ticking.current) {
raf(updateScrollDir)
ticking.current = true
} else if (onScroll && e) {
onScroll(e)
}
}
updateScrollDir()
window.addEventListener('scroll', handleScroll)
return () => window.removeEventListener('scroll', handleScroll)
}, [active, threshold])
return [direction, scrollTop]
}
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