47 lines
1.5 KiB
JavaScript
47 lines
1.5 KiB
JavaScript
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at https://mozilla.org/MPL/2.0/. */
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import { useEffect, useRef } from "react";
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/**
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* A custom react hook that sets up an IntersectionObserver to observe a single
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* or list of elements and triggers a callback when the element comes into the viewport
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* Note: The refs used should be an array type
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* @function useIntersectionObserver
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* @param {function} callback - The function to call when an element comes into the viewport
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* @param {Object} options - Options object passed to Intersection Observer:
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* https://developer.mozilla.org/en-US/docs/Web/API/IntersectionObserver/IntersectionObserver#options
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* @param {Boolean} [isSingle = false] Boolean if the elements are an array or single element
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*
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* @returns {React.MutableRefObject} a ref containing an array of elements or single element
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*
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*
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*
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*/
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function useIntersectionObserver(callback, threshold = 0.3) {
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const elementsRef = useRef([]);
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useEffect(() => {
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const observer = new IntersectionObserver(
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entries => {
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entries.forEach(entry => {
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if (entry.isIntersecting) {
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callback(entry.target);
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observer.unobserve(entry.target);
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}
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});
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},
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{ threshold }
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);
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elementsRef.current.forEach(el => {
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if (el) {
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observer.observe(el);
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}
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});
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}, [callback, threshold]);
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return elementsRef;
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}
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export { useIntersectionObserver };
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