text: /* ===========================================================
   * 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', 'cdn.jsdelivr.net'];
  
  // 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 */
          })
      );
    }
  });
  