Files
web/hooks/useStickyPosition.ts

114 lines
4.1 KiB
TypeScript

"use client"
import { useEffect } from "react"
import useStickyPositionStore, {
StickyElementNameEnum,
} from "@/stores/sticky-position"
import { debounce } from "@/utils/debounce"
interface UseStickyPositionProps {
ref?: React.RefObject<HTMLElement>
name?: StickyElementNameEnum
group?: string
}
// Global singleton ResizeObserver to observe the body only once
let resizeObserver: ResizeObserver | null = null
/**
* Custom hook to manage sticky positioning of elements within a page.
* This hook registers an element as sticky, calculates its top offset based on
* other registered sticky elements, and updates the element's position dynamically.
*
* @param {UseStickyPositionProps} props - The properties for configuring the hook.
* @param {React.RefObject<HTMLElement>} [props.ref] - A reference to the HTML element that should be sticky. Is optional to allow for other components to only get the height of the sticky elements.
* @param {StickyElementNameEnum} [props.name] - A unique name for the sticky element, used for tracking.
* @param {string} [props.group] - An optional group identifier to make multiple elements share the same top offset. Defaults to the name if not provided.
*
* @returns {Object} An object containing information about the sticky elements.
* @returns {number | null} [returns.currentHeight] - The current height of the registered sticky element, or `null` if not available.
* @returns {Array<StickyElement>} [returns.allElements] - An array containing the heights, names, and groups of all registered sticky elements.
*/
export default function useStickyPosition({
ref,
name,
group,
}: UseStickyPositionProps) {
const {
registerSticky,
unregisterSticky,
stickyElements,
updateHeights,
getAllElements,
} = useStickyPositionStore()
useEffect(() => {
if (ref && name) {
// Register the sticky element with the given ref, name, and group.
// If the group is not provided, it defaults to the value of the name.
// This registration keeps track of the sticky element and its height.
registerSticky(ref, name, group || name)
// Update the heights of all registered sticky elements.
// This ensures that the height information is accurate and up-to-date.
updateHeights()
return () => {
unregisterSticky(ref)
}
}
}, [ref, name, group, registerSticky, unregisterSticky, updateHeights])
useEffect(() => {
if (ref) {
// Find the index of the current sticky element in the array of stickyElements.
// This helps us determine its position relative to other sticky elements.
const index = stickyElements.findIndex((el) => el.ref === ref)
if (index !== -1 && ref.current) {
// Get the group name of the current sticky element.
// This will be used to filter out other elements in the same group.
const currentGroup = stickyElements[index].group
// Calculate the top offset for the current element.
// We sum the heights of all elements that appear before the current element
// in the stickyElements array, but only if they belong to a different group.
// This ensures that elements in the same group don't stack on top of each other.
const topOffset = stickyElements
.slice(0, index)
.filter((el) => el.group !== currentGroup)
.reduce((acc, el) => acc + el.height, 0)
// Apply the calculated top offset to the current element's style.
// This positions the element at the correct location within the document.
ref.current.style.top = `${topOffset}px`
}
}
}, [stickyElements, ref])
useEffect(() => {
if (!resizeObserver) {
const debouncedResizeHandler = debounce(() => {
updateHeights()
}, 100)
resizeObserver = new ResizeObserver(debouncedResizeHandler)
}
resizeObserver.observe(document.body)
return () => {
if (resizeObserver) {
resizeObserver.unobserve(document.body)
}
}
}, [updateHeights])
return {
currentHeight: ref?.current?.offsetHeight || null,
allElements: getAllElements(),
}
}