Files
puppy-tracker/src/sw.js
T
Alexander Heldt 16799ad7c7 Render sw.js with a per-build asset hash so updates are detected
The update banner only fires when the browser sees sw.js change, but the
cache name was a hand-bumped constant — so a deploy that touched only
app.js/index.html/style.css left sw.js byte-identical, no new worker
installed, and the banner never showed (and cached assets never refreshed).

Have the server render sw.js at serve time, substituting a __BUILD_HASH__
placeholder with a SHA-256 over the assets the worker caches (index.html,
style.css, app.js, manifest.json, icon.svg). Any asset change now yields a
new cache name and a byte-different sw.js, which is exactly the signal that
makes the browser install a new worker. The hash is memoised and only
recomputed when a file's size/modtime changes, so it needs no server
restart. Served unsubstituted (dev/static host), sw.js stays a valid constant.
2026-07-10 12:55:01 +00:00

88 lines
2.7 KiB
JavaScript

// BUILD is substituted per-deploy by the server with a hash of the static
// assets (see serveSW in server/main.go), so the cache name — and therefore the
// bytes of this file — change whenever any asset changes. That byte difference
// is what makes the browser install a new worker and surface the update prompt.
// Served unsubstituted (dev / a plain static host) it stays a valid constant.
const BUILD = "__BUILD_HASH__";
const CACHE = `puppy-tracker-${BUILD}`;
const PHOTO_CACHE = "puppy-tracker-photos-v1";
const ASSETS = [
"./",
"./index.html",
"./style.css",
"./app.js",
"./manifest.json",
"./icon.svg",
];
self.addEventListener("install", (event) => {
event.waitUntil(
caches.open(CACHE).then((cache) => cache.addAll(ASSETS))
);
// No skipWaiting() here: a new worker stays in "waiting" while an old one is
// controlling a tab, so the page can prompt before swapping assets out from
// under it. The page tells us to activate via a SKIP_WAITING message.
});
self.addEventListener("message", (event) => {
if (event.data && event.data.type === "SKIP_WAITING") self.skipWaiting();
});
self.addEventListener("activate", (event) => {
event.waitUntil(
caches.keys().then((keys) =>
Promise.all(
keys
.filter((k) => k !== CACHE && k !== PHOTO_CACHE)
.map((k) => caches.delete(k))
)
)
);
self.clients.claim();
});
self.addEventListener("fetch", (event) => {
const req = event.request;
if (req.method !== "GET") return;
const url = new URL(req.url);
// Photos are immutable per UUID — cache-first forever and stuff every
// successful fetch into a dedicated cache so they survive between visits
// and are available offline once seen.
if (url.pathname.includes("/api/photos/")) {
event.respondWith(
caches.open(PHOTO_CACHE).then(async (cache) => {
const cached = await cache.match(req);
if (cached) return cached;
try {
const res = await fetch(req);
if (res && res.ok) cache.put(req, res.clone());
return res;
} catch (err) {
return cached || Response.error();
}
})
);
return;
}
// Other API calls: never cache — sync must reflect live server state.
if (url.pathname.includes("/api/")) return;
event.respondWith(
caches.match(req).then((cached) => {
if (cached) return cached;
return fetch(req)
.then((res) => {
if (res && res.ok && url.origin === self.location.origin) {
const clone = res.clone();
caches.open(CACHE).then((c) => c.put(req, clone));
}
return res;
})
.catch(() => caches.match("./index.html"));
})
);
});