File size: 1,220 Bytes
1e92f2d |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 |
"use client"
import { useEffect, useRef, useState } from "react"
export const useScrollSpy = (selectors: string[]) => {
const [activeId, setActiveId] = useState<string | null>(selectors[0])
const [previousId, setPreviousId] = useState<string | null>()
const observer = useRef<IntersectionObserver | null>(null)
useEffect(() => {
const elements = selectors.map((selector) =>
document.querySelector(`[id='${selector.replace("#", "")}']`),
)
observer.current = new IntersectionObserver(
(entries) => {
for (const entry of entries) {
const id = `#${entry.target.getAttribute("id")}`
if (entry?.isIntersecting) {
setPreviousId(activeId)
setActiveId(id)
} else {
if (id === previousId) {
setPreviousId(null)
}
if (activeId === id && previousId) {
setActiveId(previousId)
}
}
}
},
{ rootMargin: "-30% 0px" },
)
for (const element of elements) {
if (element) observer.current?.observe(element)
}
return () => observer.current?.disconnect()
}, [selectors, previousId, activeId])
return activeId
}
|