website: redesign part 11

website_next/learn/charts/intersection.js

@@ -0,0 +1,14 @@
+/**
+ * @param {Element} element
+ * @param {() => void} callback
+ */
+export function onFirstIntersection(element, callback) {
+  const observer = new IntersectionObserver((entries) => {
+    if (!entries[0].isIntersecting) return;
+
+    observer.disconnect();
+    callback();
+  });
+
+  observer.observe(element);
+}