https://sixtysevenradio.com/observer.js

1let elements = document.querySelectorAll('.animate_observer')
2
3// Check for broswer support. If none, reset elements waiting for observer.
4if (window.IntersectionObserver) {
5
6	function observer_callback(e) {
7		e.forEach(function (item, index) {
8			if (e[index].isIntersecting) {
9				e[index].target.style.animationPlayState = 'running';
10			}
11		})
12	}
13
14	let observer = new IntersectionObserver(observer_callback, {threshold:0.5});
15	elements.forEach(function (item, index) {
16		observer.observe(item)
17	})
18
19}
20
21else {
22
23	elements.forEach(function (item, index) {
24		console.log(item)
25		item.style.animation = 'none'
26	})
27
28}