feat: add pwa support

service-worker.js

@@ -0,0 +1,56 @@
+const CACHE_NAME = 'weltzeit-cache-v1';
+const PRECACHE_RESOURCES = [
+  './',
+  './index.html',
+  './styles.css',
+  './app.js',
+  './zones.js',
+  './manifest.webmanifest',
+  './icons/icon-192.png',
+  './icons/icon-512.png'
+];
+
+self.addEventListener('install', (event) => {
+  event.waitUntil(
+    caches.open(CACHE_NAME).then((cache) => cache.addAll(PRECACHE_RESOURCES))
+  );
+});
+
+self.addEventListener('activate', (event) => {
+  event.waitUntil(
+    caches.keys().then((cacheNames) =>
+      Promise.all(
+        cacheNames.map((cacheName) => {
+          if (cacheName !== CACHE_NAME) {
+            return caches.delete(cacheName);
+          }
+          return undefined;
+        })
+      )
+    )
+  );
+});
+
+self.addEventListener('fetch', (event) => {
+  if (event.request.method !== 'GET') {
+    return;
+  }
+
+  event.respondWith(
+    caches.match(event.request).then((cachedResponse) => {
+      if (cachedResponse) {
+        return cachedResponse;
+      }
+
+      return fetch(event.request)
+        .then((response) => {
+          const responseClone = response.clone();
+          caches.open(CACHE_NAME).then((cache) => {
+            cache.put(event.request, responseClone);
+          });
+          return response;
+        })
+        .catch(() => caches.match('./index.html'));
+    })
+  );
+});