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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,

'fonts.gstatic.com',

'fonts.googleapis.com',

'unpkg.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 */ })

)

}

})