bible/books/sw.js

// Generated by render_books.py -- do not edit by hand.
//
// STRATEGY decides what a same-origin GET does:
//
//   network-first  ask the network, fall back to the cache when it fails.
//                  Offline, fetch rejects immediately, so the fallback is
//                  effectively instant -- the only cost is one round trip
//                  while online, and you never see a stale page.
//   cache-first    answer from the cache the moment there is a hit. Fastest
//                  possible load, but a rebuild needs two reloads to appear.
//
// Either way every response that arrives is written back to the cache, so the
// offline copy stays current, and a new build changes VERSION, dropping the
// caches belonging to older builds.
const STRATEGY = 'network-first';
const NETWORK_TIMEOUT_MS = 3000;
const VERSION = 'c5d29c3cdf15';
const CACHE = 'bible-' + VERSION;
const ASSETS = [
  "./",
  "./1CH.html",
  "./1CO.html",
  "./1ES.html",
  "./1JN.html",
  "./1KI.html",
  "./1MA.html",
  "./1PE.html",
  "./1SA.html",
  "./1TH.html",
  "./1TI.html",
  "./2CH.html",
  "./2CO.html",
  "./2ES.html",
  "./2JN.html",
  "./2KI.html",
  "./2MA.html",
  "./2PE.html",
  "./2SA.html",
  "./2TH.html",
  "./2TI.html",
  "./3JN.html",
  "./3MA.html",
  "./4MA.html",
  "./ACT.html",
  "./AMO.html",
  "./BAR.html",
  "./COL.html",
  "./DAG.html",
  "./DAN.html",
  "./DEU.html",
  "./ECC.html",
  "./EPH.html",
  "./ESG.html",
  "./EST.html",
  "./EXO.html",
  "./EZK.html",
  "./EZR.html",
  "./FRT.html",
  "./GAL.html",
  "./GEN.html",
  "./GLO.html",
  "./HAB.html",
  "./HAG.html",
  "./HEB.html",
  "./HOS.html",
  "./ISA.html",
  "./JAS.html",
  "./JDG.html",
  "./JDT.html",
  "./JER.html",
  "./JHN.html",
  "./JOB.html",
  "./JOL.html",
  "./JON.html",
  "./JOS.html",
  "./JUD.html",
  "./LAM.html",
  "./LEV.html",
  "./LUK.html",
  "./MAL.html",
  "./MAN.html",
  "./MAT.html",
  "./MIC.html",
  "./MRK.html",
  "./NAM.html",
  "./NEH.html",
  "./NUM.html",
  "./OBA.html",
  "./PHM.html",
  "./PHP.html",
  "./PRO.html",
  "./PS2.html",
  "./PSA.html",
  "./REV.html",
  "./ROM.html",
  "./RUT.html",
  "./SIR.html",
  "./SNG.html",
  "./TIT.html",
  "./TOB.html",
  "./WIS.html",
  "./ZEC.html",
  "./ZEP.html",
  "./app.js",
  "./bible.css",
  "./icons/apple-touch-icon.png",
  "./icons/icon-192.png",
  "./icons/icon-512.png",
  "./index.html",
  "./manifest.webmanifest"
];

self.addEventListener('install', (event) => {
  event.waitUntil((async () => {
    const cache = await caches.open(CACHE);
    // Added one at a time rather than addAll(): addAll is atomic, so a single
    // failed asset would leave the app with no offline copy at all.
    let failed = 0;
    await Promise.all(ASSETS.map((url) =>
      cache.add(new Request(url, { cache: 'reload' })).catch(() => { failed++; })));
    if (failed) console.warn('precache: ' + failed + ' of ' + ASSETS.length + ' failed');
    await self.skipWaiting();
  })());
});

self.addEventListener('activate', (event) => {
  event.waitUntil((async () => {
    const keys = await caches.keys();
    await Promise.all(keys
      .filter((k) => k.startsWith('bible-') && k !== CACHE)
      .map((k) => caches.delete(k)));
    await self.clients.claim();
  })());
});

self.addEventListener('fetch', (event) => {
  const req = event.request;
  if (req.method !== 'GET') return;
  if (new URL(req.url).origin !== location.origin) return;
  event.respondWith(respond(event));
});

// Aborted rather than raced, so a hung request is actually torn down instead
// of leaking while the cache answers.
async function fromNetwork(req) {
  const controller = new AbortController();
  const timer = setTimeout(() => controller.abort(), NETWORK_TIMEOUT_MS);
  try {
    return await fetch(req, { signal: controller.signal });
  } finally {
    clearTimeout(timer);
  }
}

function cached(req) {
  return caches.match(req, { ignoreSearch: true });
}

async function respond(event) {
  const req = event.request;

  if (STRATEGY === 'cache-first') {
    const hit = await cached(req);
    if (hit) return hit;
  }

  try {
    const res = await fromNetwork(req);
    if (res && res.ok && res.type === 'basic') {
      const copy = res.clone();
      // Not awaited: the response should not wait on the cache write.
      event.waitUntil(caches.open(CACHE).then((c) => c.put(req, copy)));
    }
    return res;
  } catch (err) {
    const hit = await cached(req);
    if (hit) return hit;
    // Offline and never cached. Navigations get the index rather than the
    // browser's error page; anything else genuinely fails.
    if (req.mode === 'navigate') {
      const index = await cached('./index.html');
      if (index) return index;
    }
    throw err;
  }
}