WFDASH-WEBAPP/public/sw.js

const CACHE_NAME = "wfdash-v1";
const OFFLINE_URL = "/offline";

const PRECACHE_ASSETS = [
  "/",
  "/offline",
  "/manifest.json",
];

self.addEventListener("install", (event) => {
  event.waitUntil(
    caches.open(CACHE_NAME).then((cache) => {
      return cache.addAll(PRECACHE_ASSETS);
    })
  );
  self.skipWaiting();
});

self.addEventListener("activate", (event) => {
  event.waitUntil(
    caches.keys().then((keys) => {
      return Promise.all(
        keys.filter((key) => key !== CACHE_NAME).map((key) => caches.delete(key))
      );
    })
  );
  self.clients.claim();
});

self.addEventListener("fetch", (event) => {
  if (event.request.method !== "GET") return;
  if (event.request.url.includes("/api/")) return;

  event.respondWith(
    fetch(event.request)
      .then((response) => {
        const clone = response.clone();
        caches.open(CACHE_NAME).then((cache) => {
          cache.put(event.request, clone);
        });
        return response;
      })
      .catch(() => {
        return caches.match(event.request).then((cached) => {
          if (cached) return cached;
          if (event.request.mode === "navigate") {
            return caches.match(OFFLINE_URL);
          }
          return new Response("Offline", { status: 503 });
        });
      })
  );
});