From 8a4503c925f60709287ce6f39545583f7c48d747 Mon Sep 17 00:00:00 2001
From: ray <gitea@rayelliott.dev>
Date: Thu, 21 May 2020 16:10:37 +0100
Subject: [PATCH] add onscreen function

---
 src/js/index.js | 23 ++++++++++++++++++++---
 1 file changed, 20 insertions(+), 3 deletions(-)

diff --git a/src/js/index.js b/src/js/index.js
index 7d4cebb..59c5909 100644
--- a/src/js/index.js
+++ b/src/js/index.js
@@ -1,5 +1,22 @@
 (function() {
-  window.addEventListener("DOMContentLoaded", event => {
-    // TODO
-  });
+	window.addEventListener('DOMContentLoaded', event => {
+		function onScreenHandler(entries) {
+			entries.forEach(entry => {
+				if (entry.intersectionRatio > 0) {
+					entry.target.classList.add('is-showing', 'has-shown');
+				} else {
+					entry.target.classList.remove('is-showing');
+				}
+			});
+		}
+
+		document.querySelectorAll('.js-onscreen').forEach(el => {
+			const options = {
+				rootMargin: '0px',
+				threshold: [0, 1],
+			};
+			const observer = new IntersectionObserver(onScreenHandler, options);
+			observer.observe(el);
+		});
+	});
 })();