https://lightbox-archive.com/assets/js/fade-in.js

1let sharedObserver = null;
2
3function getObserver() {
4  if (!sharedObserver) {
5    sharedObserver = new IntersectionObserver(
6      (entries) => {
7        for (const entry of entries) {
8          if (entry.isIntersecting) {
9            entry.target.classList.add('is-visible');
10            sharedObserver.unobserve(entry.target);
11          }
12        }
13      },
14      { threshold: 0.1, rootMargin: '0px 0px 100px 0px' }
15    );
16  }
17  return sharedObserver;
18}
19
20export function observeFadeIn(elements) {
21  const observer = getObserver();
22  elements.forEach((el) => {
23    if (el.classList && el.classList.contains('fade-in')) observer.observe(el);
24  });
25}
26
27export function initFadeIn(root = document) {
28  observeFadeIn(Array.from(root.querySelectorAll('.fade-in')));
29}