1 files changed, 54 insertions, 0 deletions
diff --git a/ui/service-worker.js b/ui/service-worker.js
new file mode 100644
index 0000000..e2143b3
--- /dev/null
+++ b/ui/service-worker.js
@@ -0,0 +1,54 @@
+/// <reference types="@sveltejs/kit" />
+/// <reference no-default-lib="true"/>
+/// <reference lib="esnext" />
+/// <reference lib="webworker" />
+
+// Because of this line, this service worker won't run in dev mode in Firefox.
+// Only Safari, Edge, Chrome can run it at the moment, because only they
+// support modules in service workers.
+//
+// That's okay! If you run `tools/run` with PILCROW_DEV unset, you will get the
+// bundled version, and can work on it. Or just use Safari.
+import { build, files, version } from '$service-worker';
+
+// Create a unique cache name for this deployment
+const CACHE = `cache-${version}`;
+
+const ASSETS = [
+	...build, // the app itself
+	...files  // everything in `static`
+];
+
+self.addEventListener('install', (event) => {
+	// Create a new cache and add all files to it
+	async function addFilesToCache() {
+		const cache = await caches.open(CACHE);
+		await cache.addAll(ASSETS);
+	}
+
+	event.waitUntil(addFilesToCache());
+});
+
+self.addEventListener('activate', (event) => {
+	// Remove previous cached data from disk
+	async function deleteOldCaches() {
+		for (const key of await caches.keys()) {
+			if (key !== CACHE) await caches.delete(key);
+		}
+	}
+
+	event.waitUntil(deleteOldCaches());
+});
+
+// The simplest possible use of the caches above:
+async function cacheFirst(request) {
+  const responseFromCache = await caches.match(request);
+  if (responseFromCache) {
+    return responseFromCache;
+  }
+  return fetch(request);
+};
+
+self.addEventListener("fetch", (event) => {
+  event.respondWith(cacheFirst(event.request));
+});