/* ===========================================================
* sw.js * =========================================================== * Copyright 2016 @huxpro * Licensed under Apache 2.0 * Register service worker. * ========================================================== */
const PRECACHE = 'precache-v1'; const RUNTIME = 'runtime'; const HOSTNAME_WHITELIST = [
self.location.hostname, "aiokr.github.io",
]
// The Util Function to hack URLs of intercepted requests const getFixedUrl = (req) => {
var now = Date.now(); url = new URL(req.url) // 1. fixed http URL // Just keep syncing with location.protocol // fetch(httpURL) belongs to active mixed content. // And fetch(httpRequest) is not supported yet. url.protocol = self.location.protocol // 2. add query for caching-busting. // Github Pages served with Cache-Control: max-age=600 // max-age on mutable content is error-prone, with SW life of bugs can even extend. // Until cache mode of Fetch API landed, we have to workaround cache-busting with query string. // Cache-Control-Bug: https://bugs.chromium.org/p/chromium/issues/detail?id=453190 url.search += (url.search ? '&' : '?') + 'cache-bust=' + now; return url.href
}
// The Util Function to detect and polyfill req.mode=“navigate” // request.mode of 'navigate' is unfortunately not supported in Chrome // versions older than 49, so we need to include a less precise fallback, // which checks for a GET request with an Accept: text/html header. const isNavigationReq = (req) => (req.mode === 'navigate' || (req.method === 'GET' && req.headers.get('accept').includes('text/html')))
// The Util Function to detect if a req is end with extension // Accordin to Fetch API spec <fetch.spec.whatwg.org/#concept-request-destination> // Any HTML's navigation has consistently mode=“navigate” type=“” and destination=“document” // including requesting an img (or any static resources) from URL Bar directly. // So It ends up with that regExp is still the king of URL routing ;) // P.S. An url.pathname has no '.' can not indicate it ends with extension (e.g. /api/version/1.2/) const endWithExtension = (req) => Boolean(new URL(req.url).pathname.match(/.w+$/))
// Redirect in SW manually fixed github pages arbitray 404s on things?blah // what we want: // repo?blah -> !(gh 404) -> sw 302 -> repo/?blah // .ext?blah -> !(sw 302 -> .ext/?blah -> gh 404) -> .ext?blah // If It's a navigation req and it's url.pathname isn't end with '/' or '.ext' // it should be a dir/repo request and need to be fixed (a.k.a be redirected) // Tracking twitter.com/Huxpro/status/798816417097224193 const shouldRedirect = (req) => (isNavigationReq(req) && new URL(req.url).pathname.substr(-1) !== “/” && !endWithExtension(req))
// The Util Function to get redirect URL // `${url}/` would mis-add “/” in the end of query, so we use URL object. // P.P.S. Always trust url.pathname instead of the whole url string. const getRedirectUrl = (req) => {
url = new URL(req.url) url.pathname += "/" return url.href
}
/**
* @Lifecycle Install * Precache anything static to this version of your app. * e.g. App Shell, 404, JS/CSS dependencies... * * waitUntil() : installing ====> installed * skipWaiting() : waiting(installed) ====> activating */
self.addEventListener('install', e => {
e.waitUntil( caches.open(PRECACHE).then(cache => { return cache.add('offline.html') .then(self.skipWaiting()) .catch(err => console.log(err)) }) )
});
/**
* @Lifecycle Activate * New one activated when old isnt being used. * * waitUntil(): activating ====> activated */
self.addEventListener('activate', event => {
console.log('service worker activated.') event.waitUntil(self.clients.claim());
});
/**
* @Functional Fetch * All network requests are being intercepted here. * * void respondWith(Promise<Response> r); */
self.addEventListener('fetch', event => {
// logs for debugging console.log(`fetch ${event.request.url}`) //console.log(` - type: ${event.request.type}; destination: ${event.request.destination}`) //console.log(` - mode: ${event.request.mode}, accept: ${event.request.headers.get('accept')}`) // Skip some of cross-origin requests, like those for Google Analytics. if (HOSTNAME_WHITELIST.indexOf(new URL(event.request.url).hostname) > -1) { // Redirect in SW manually fixed github pages 404s on repo?blah if(shouldRedirect(event.request)){ event.respondWith(Response.redirect(getRedirectUrl(event.request))) return; } // Stale-while-revalidate // similar to HTTP's stale-while-revalidate: https://www.mnot.net/blog/2007/12/12/stale // Upgrade from Jake's to Surma's: https://gist.github.com/surma/eb441223daaedf880801ad80006389f1 const cached = caches.match(event.request); const fixedUrl = getFixedUrl(event.request); const fetched = fetch(fixedUrl, {cache: "no-store"}); const fetchedCopy = fetched.then(resp => resp.clone()); // Call respondWith() with whatever we get first. // If the fetch fails (e.g disconnected), wait for the cache. // If there’s nothing in cache, wait for the fetch. // If neither yields a response, return offline pages. event.respondWith( Promise.race([fetched.catch(_ => cached), cached]) .then(resp => resp || fetched) .catch(_ => caches.match('offline.html')) ); // Update the cache with the version we fetched (only for ok status) event.waitUntil( Promise.all([fetchedCopy, caches.open(RUNTIME)]) .then(([response, cache]) => response.ok && cache.put(event.request, response)) .catch(_ => {/* eat any errors */}) ); }
});