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sw.js
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sw.js
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/* ===========================================================
* docsify sw.js
* ===========================================================
* Copyright 2016 @huxpro
* Licensed under Apache 2.0
* Register service worker.
* ========================================================== */
const RUNTIME = 'docsify'
const HOSTNAME_WHITELIST = [
self.location.hostname,
'img.shields.io',
'static.hotjar.com',
'fonts.gstatic.com',
'fonts.googleapis.com',
'www.google-analytics.com',
'avatars1.githubusercontent.com'
]
// The Util Function to hack URLs of intercepted requests
const getFixedUrl = (req) => {
var now = Date.now()
var 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
if (url.hostname === self.location.hostname) {
url.search += (url.search ? '&' : '?') + 'cache-bust=' + now
}
return url.href
}
/**
* @Lifecycle Activate
* New one activated when old isnt being used.
*
* waitUntil(): activating ====> activated
*/
self.addEventListener('activate', event => {
event.waitUntil(self.clients.claim())
})
/**
* @Functional Fetch
* All network requests are being intercepted here.
*
* void respondWith(Promise<Response> r)
*/
self.addEventListener('fetch', event => {
// Skip some of cross-origin requests, like those for Google Analytics.
if (HOSTNAME_WHITELIST.indexOf(new URL(event.request.url).hostname) > -1) {
// 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(_ => { /* eat any errors */ })
)
// 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 */ })
)
}
})