0f2e109aa2
The three things a browser asks for, without a plugin: a manifest in
public/ (name, /app as the start, three icons cut from the one piece of
art this repo has), a service worker, and the two metas iOS reads
instead of the manifest.
The worker caches the shell — /, /app, /library, all one document under
the SPA fallback — and the hashed assets the build emits. A navigation
is network-first, so a deploy is never pinned behind the cache; a
hashed asset or the wasm is cache-first, because under a given build
those never change. /api and any non-GET go straight out: a worker is a
cache, not a proxy. nginx serves sw.js and manifest.json `no-cache`
(both names outlive their contents) with the isolation headers the
worker script needs under COEP.
The offer is the app's own dialog, not Chromium's mini-infobar: the
event is held, and it is spent either after the visitor has been in the
studio two minutes or the moment an export lands — the point at which
the app has done their work. Safari never fires the event, so it gets
the Share > Add to Home Screen line instead. A refusal is remembered and
never asked again.
node scripts/make-icons.mjs 192x192 39785B / 512x512 159296B / maskable 512x512 123723B
node scripts/pwa-check.mjs manifest 3 icons · worker activated · shell cached
· offline reload of /app paints
off (https://localhost:8090) same four, through nginx
77 lines
3.3 KiB
JavaScript
77 lines
3.3 KiB
JavaScript
// The app shell as a service worker, so an installed RecipesCam opens with no
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// network at all. Not bundled on purpose: through vite/rollup it would stop being
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// readable in DevTools, the one place a worker gets debugged. VERSION is the cache
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// name and the whole update story — bump it when the shell changes, and `activate`
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// drops every older cache.
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const VERSION = 'recipescam-v1';
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// nginx answers all three with the same index.html (SPA fallback), so they are one
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// document under three keys: an offline navigation finds it whichever key it asks.
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const SHELL = ['/', '/app', '/library'];
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// Cache-first paths: vite hashes every filename in its own bundle, and the wasm,
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// the models and the icons never change under a given build.
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const STATIC = /^\/(assets|wasm|models|icons)\//;
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// Only a complete same-origin 200 is worth keeping — an opaque or error body
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// stored here comes back as a failure on the next visit, and nothing in the worker
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// can tell the two apart by then.
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const cachedFetch = (request) =>
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fetch(request).then((response) => {
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if (response.ok) {
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const copy = response.clone();
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caches.open(VERSION).then((cache) => cache.put(request, copy));
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}
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return response;
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});
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// Offline, the studio the app is for; the landing page for a build without /app.
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const offlineShell = async () =>
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(await caches.match('/app')) ?? (await caches.match('/')) ?? Response.error();
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self.addEventListener('install', (event) => {
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// Best effort, one route at a time: a deploy caught mid-flight must not leave the
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// worker uninstalled, so each route fails on its own.
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event.waitUntil(
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caches.open(VERSION)
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.then((cache) => Promise.all(SHELL.map((url) => cache.add(url).catch(() => {}))))
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.then(() => self.skipWaiting()),
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);
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});
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self.addEventListener('activate', (event) => {
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event.waitUntil(
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caches.keys()
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.then((names) => Promise.all(names.filter((n) => n !== VERSION).map((n) => caches.delete(n))))
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.then(() => self.clients.claim()),
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);
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});
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self.addEventListener('fetch', (event) => {
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const { request } = event;
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// A worker is a cache, not a proxy: a POST, the API, another origin's font — a
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// request that is not a plain same-origin read — goes straight out.
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if (request.method !== 'GET') return;
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const url = new URL(request.url);
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if (url.origin !== self.location.origin || url.pathname.startsWith('/api/')) return;
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// A navigation is network-first even when it is cached: a shell answered from the
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// cache while the network holds a newer build pins the visitor to the old one. It
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// is also the path an installed app opens through with no network.
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if (request.mode === 'navigate') {
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event.respondWith(fetch(request).catch(offlineShell));
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return;
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}
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// ponytail: a navigation is never written back, the precached entry is what
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// answers offline. Add a put() here once a route must survive on its own.
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if (STATIC.test(url.pathname)) {
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event.respondWith(caches.match(request).then((hit) => hit ?? cachedFetch(request)));
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return;
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}
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// Everything else — a font, the manifest, an uploaded photo — is network-first,
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// and answered from the cache only when that fails.
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event.respondWith(fetch(request).catch(async () => (await caches.match(request)) ?? Response.error()));
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});
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