134 lines
4.6 KiB
TypeScript
134 lines
4.6 KiB
TypeScript
"use client"
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import { useCallback, useEffect } from "react"
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import useStickyPositionStore, {
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type StickyElement,
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type StickyElementNameEnum,
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} from "../stores/sticky-position"
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import { debounce } from "../utils/debounce"
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interface UseStickyPositionProps {
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ref?: React.RefObject<HTMLElement | null>
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name?: StickyElementNameEnum
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group?: string
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}
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// Global singleton ResizeObserver to observe the body only once
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let resizeObserver: ResizeObserver | null = null
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/**
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* Custom hook to manage sticky positioning of elements within a page.
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* This hook registers an element as sticky, calculates its top offset based on
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* other registered sticky elements, and updates the element's position dynamically.
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*
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* @param {UseStickyPositionProps} [props] - The properties for configuring the hook.
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* @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.
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* @param {StickyElementNameEnum} [props.name] - A unique name for the sticky element, used for tracking.
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* @param {string} [props.group] - An optional group identifier to make multiple elements share the same top offset. Defaults to the name if not provided.
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*
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* @returns {Object} An object containing information about the sticky elements.
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* @returns {number | null} [returns.currentHeight] - The current height of the registered sticky element, or `null` if not available.
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* @returns {Array<StickyElement>} [returns.allElements] - An array containing the heights, names, and groups of all registered sticky elements.
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*/
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export default function useStickyPosition({
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ref,
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name,
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group,
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}: UseStickyPositionProps = {}) {
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const {
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registerSticky,
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unregisterSticky,
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stickyElements,
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updateHeights,
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getAllElements,
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} = useStickyPositionStore()
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const baseTopOffset = 0
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useEffect(() => {
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if (ref && name) {
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// Register the sticky element with the given ref, name, and group.
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// If the group is not provided, it defaults to the value of the name.
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// This registration keeps track of the sticky element and its height.
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registerSticky(ref, name, group || name)
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// Update the heights of all registered sticky elements.
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// This ensures that the height information is accurate and up-to-date.
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updateHeights()
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return () => {
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unregisterSticky(ref)
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}
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}
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}, [ref, name, group, registerSticky, unregisterSticky, updateHeights])
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/**
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* Get the top position of element at index `index`
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*
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* Calculates the total height of all sticky elements _before_ the element
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* at position `index`. If `index` is not provided all elements are included
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* in the calculation. Takes grouping into consideration (only counts one
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* element per group)
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*/
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const getTopOffset = useCallback(
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(index?: number) => {
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// Get the group name of the current sticky element.
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// This will be used to only count one element per group.
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const elementGroup = index ? stickyElements[index].group : undefined
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return stickyElements
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.slice(0, index)
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.reduce<StickyElement[]>((acc, curr) => {
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if (
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(elementGroup && curr.group === elementGroup) ||
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acc.some((elem: StickyElement) => elem.group === curr.group)
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) {
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return acc
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}
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return [...acc, curr]
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}, [])
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.reduce((acc, el) => acc + el.height, baseTopOffset)
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},
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[baseTopOffset, stickyElements]
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)
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useEffect(() => {
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if (ref) {
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// Find the index of the current sticky element in the array of stickyElements.
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// This helps us determine its position relative to other sticky elements.
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const index = stickyElements.findIndex((el) => el.ref === ref)
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if (index !== -1 && ref.current) {
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const topOffset = getTopOffset(index)
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// Apply the calculated top offset to the current element's style.
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// This positions the element at the correct location within the document.
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ref.current.style.top = `${topOffset}px`
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}
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}
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}, [baseTopOffset, stickyElements, ref, getTopOffset])
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useEffect(() => {
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if (!resizeObserver) {
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const debouncedResizeHandler = debounce(() => {
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updateHeights()
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}, 100)
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resizeObserver = new ResizeObserver(debouncedResizeHandler)
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}
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resizeObserver.observe(document.body)
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return () => {
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if (resizeObserver) {
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resizeObserver.unobserve(document.body)
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}
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}
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}, [updateHeights])
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return {
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currentHeight: ref?.current?.offsetHeight || null,
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allElements: getAllElements(),
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getTopOffset,
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}
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}
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