We are a PWA

public/service-worker.js

@@ -0,0 +1,52 @@
+var version = "v1.0";
+var cacheName = "::vinlottis";
+var CACHE_NAME = version + cacheName;
+var STATIC_CACHE_URLS = ["/"];
+
+self.addEventListener("activate", event => {
+  event.waitUntil(
+    caches
+      .keys()
+      .then(keys => keys.filter(key => key !== CACHE_NAME))
+      .then(keys =>
+        Promise.all(
+          keys.map(key => {
+            console.log(`Deleting cache ${key}`);
+            return caches.delete(key);
+          })
+        )
+      )
+  );
+});
+
+self.addEventListener("install", event => {
+  console.log("Service Worker installing.");
+  event.waitUntil(
+    caches.open(CACHE_NAME).then(cache => cache.addAll(STATIC_CACHE_URLS))
+  );
+});
+
+self.addEventListener("fetch", event => {
+  event.respondWith(
+    fetch(event.request).catch(function() {
+      return caches.match(event.request);
+    })
+  );
+  event.waitUntil(
+    fetch(event.request)
+      .then(function(response) {
+        cache(event.request, response);
+      })
+      .catch(error => {})
+  );
+});
+
+function cache(request, response) {
+  if (response.type === "error" || response.type === "opaque") {
+    return Promise.resolve(); // do not put in cache network errors
+  }
+
+  return caches
+    .open(CACHE_NAME)
+    .then(cache => cache.put(request, response.clone()));
+}