https://hidden.com/service-worker.js

1// BUILD_ID is injected via importScripts from /_sw-version.js (served by
2// pages/api/sw-version.ts) as a bare lexical global (`const BUILD_ID = "..."`).
3// The browser re-fetches imported scripts during the update check (thanks to
4// updateViaCache: "none" on the registration), so changing /_sw-version.js
5// triggers install -> waiting -> activate.
6//
7// importScripts is wrapped because a synchronous throw here (e.g. /_sw-version.js
8// returning 503 during a deploy) would abort the entire SW. Falling back to a
9// placeholder keeps the SW functional; the next update check will re-import.
10// The `typeof` guard also covers a 200-with-non-declaring-body anomaly, where
11// importScripts succeeds but never declares BUILD_ID — a bare reference would
12// then ReferenceError and brick the SW.
13let resolvedBuildId = "unknown";
14try {
15  importScripts("/_sw-version.js");
16  if (typeof BUILD_ID !== "undefined") resolvedBuildId = BUILD_ID;
17} catch (e) {
18  // Keep the "unknown" fallback; the next update check re-imports.
19}
20
21const CACHE_NAME = `hidden-static-${resolvedBuildId}`;
22
23self.addEventListener("install", (event) => {
24  // No skipWaiting here — the client decides when to promote via the
25  // SKIP_WAITING message. That keeps a single path for activation and
26  // allows the existing controller to remain in charge until the client
27  // is ready to switch over.
28});
29
30self.addEventListener("activate", (event) => {
31  event.waitUntil(
32    caches.keys()
33      .then(names => Promise.all(
34        names
35          .filter(n => n.startsWith("hidden-static-") && n !== CACHE_NAME)
36          .map(n => caches.delete(n))
37      ))
38      .then(() => self.clients.claim())
39  );
40});
41
42self.addEventListener("fetch", (event) => {
43  const { request } = event;
44
45  if (request.method !== "GET") return;
46
47  if (request.mode === "navigate") {
48    event.respondWith(
49      fetch(request).catch(() => caches.match(request))
50    );
51    return;
52  }
53
54  if (request.url.includes("/_next/static/")) {
55    event.respondWith(
56      caches.match(request).then(cached => {
57        if (cached) return cached;
58        return fetch(request).then(response => {
59          if (response.ok) {
60            const clone = response.clone();
61            caches.open(CACHE_NAME).then(cache => cache.put(request, clone));
62          }
63          return response;
64        });
65      })
66    );
67    return;
68  }
69});
70
71self.addEventListener("message", (event) => {
72  if (event.data?.type === "SKIP_WAITING") {
73    self.skipWaiting();
74  }
75});