website_next: snapshot

website_next/chart/intersection.js

@@ -0,0 +1,21 @@
+const lifecycleByElement = new WeakMap();
+const observer = new IntersectionObserver(
+  (entries) => {
+    for (const entry of entries) {
+      const lifecycle = lifecycleByElement.get(entry.target);
+      lifecycle?.[entry.isIntersecting ? "show" : "hide"]();
+    }
+  },
+  {
+    rootMargin: "400px 0px",
+  },
+);
+
+/**
+ * @param {Element} element
+ * @param {{ show: () => void, hide: () => void }} lifecycle
+ */
+export function onChartVisibility(element, lifecycle) {
+  lifecycleByElement.set(element, lifecycle);
+  observer.observe(element);
+}