cache static assets

app/service-worker/cache-utils.ts

@@ -0,0 +1,32 @@
+import type { FetchEventWithPreloadResponse } from "./fetch";
+
+export const ASSET_CACHE = "asset-cache";
+
+export async function cacheAsset(event: FetchEventWithPreloadResponse) {
+	const url = new URL(event.request.url);
+	const cachedResponse = await caches.match(event.request, {
+		cacheName: ASSET_CACHE,
+		ignoreVary: true,
+		ignoreSearch: true,
+	});
+
+	console.debug(`Serving asset from ${cachedResponse ? "cache" : " network"}`, url.pathname);
+
+	const fetchPromise = (async () => {
+		const cache = await caches.open(ASSET_CACHE);
+		const preloadedResponse = await event.preloadResponse;
+		const response = preloadedResponse || (await fetch(event.request));
+		switch (response.status) {
+			case 200:
+				cache.put(event.request, response.clone());
+				break;
+			case 404:
+				cache.delete(event.request);
+				break;
+		}
+
+		return response;
+	})();
+
+	return cachedResponse || fetchPromise;
+}

app/service-worker/fetch.ts

@@ -1,9 +1,12 @@
+import { ASSET_CACHE, cacheAsset } from "~/service-worker/cache-utils";
+
 declare let self: ServiceWorkerGlobalScope;
 
-export default async function handleFetch(event: FetchEvent & { preloadResponse?: Promise<Response | undefined> }) {
-	const preloaded = await event.preloadResponse;
-	if (preloaded) {
-		return preloaded;
+export type FetchEventWithPreloadResponse = FetchEvent & { preloadResponse?: Promise<Response | undefined> };
+
+export default async function handleFetch(event: FetchEventWithPreloadResponse) {
+	if (["font", "image", "script", "style"].includes(event.request.destination)) {
+		return cacheAsset(event);
 	}
 
 	return fetch(event.request);