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sw.js
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sw.js
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/* ===========================================================
* 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,
"huangxuan.me",
"yanshuo.io",
"cdnjs.cloudflare.com"
]
// 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 <https://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+$/))
// Redirect in SW manually fixed github pages arbitray 404s on things?blah
// what we want:
// repo?blah -> !(gh 404) -> sw 302 -> repo/?blah
// .ext?blah -> !(sw 302 -> .ext/?blah -> gh 404) -> .ext?blah
// If It's a navigation req and it's url.pathname isn't end with '/' or '.ext'
// it should be a dir/repo request and need to be fixed (a.k.a be redirected)
// Tracking https://twitter.com/Huxpro/status/798816417097224193
const shouldRedirect = (req) => (isNavigationReq(req) && new URL(req.url).pathname.substr(-1) !== "/" && !endWithExtension(req))
// The Util Function to get redirect URL
// `${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 */})
);
}
});