Initial add

sw.js

@@ -0,0 +1,52 @@
+// Establish a cache name
+const cacheName = 'dandelion_cache_v1';
+
+const contentToCache = [
+    "/index.html",
+    "/main.js",
+    "/favicon.ico",
+  ];
+
+self.addEventListener('install', (e) => {
+    e.waitUntil(
+        (async () => {
+          const cache = await caches.open(cacheName);
+          console.log("[Service Worker] Caching all: app shell and content", contentToCache);
+          await cache.addAll(contentToCache);
+        })(),
+      );
+});
+
+self.addEventListener("fetch", (e) => {
+    e.respondWith(
+      (async () => {
+        const r = await caches.match(e.request);
+        console.log(`[Service Worker] Fetching resource: ${e.request.url}`);
+        if (r) {
+          return r;
+        }
+        try {
+            const response = await fetch(e.request);
+        } catch(e) {
+            console.warn(e);
+        }
+        const cache = await caches.open(cacheName);
+        console.log(`[Service Worker] Caching new resource: ${e.request.url}`);
+        cache.put(e.request, response.clone());
+        return response;
+      })(),
+    );
+  });
+
+  addEventListener("message", async (e) => {
+    console.log(`Message received: ${e.data}`);
+
+    switch (e.data.type) {
+        case "updateMain": 
+        const cache = await caches.open(cacheName);
+        console.log(`[Service Worker] Caching new resource: main.js`);
+        cache.put("/main.js", new Response());
+        break;
+    }
+  });
+