feat(pwa): add sw.js

Author: QingWei-Li

docs/index.html

@@ -32,6 +32,10 @@
       '/changelog': 'https://raw.githubusercontent.com/QingWei-Li/docsify/master/CHANGELOG'
     }
   }
+
+  if (typeof navigator.serviceWorker !== 'undefined') {
+    navigator.serviceWorker.register('sw.js')
+  }
 </script>
 <script src="//unpkg.com/docsify/lib/docsify.min.js"></script>
 <script src="//unpkg.com/docsify/lib/plugins/search.min.js"></script>

docs/sw.js

@@ -0,0 +1,82 @@
+/* ===========================================================
+ * docsify sw.js
+ * ===========================================================
+ * Copyright 2016 @huxpro
+ * Licensed under Apache 2.0
+ * Register service worker.
+ * ========================================================== */
+
+const RUNTIME = 'docsify';
+const HOSTNAME_WHITELIST = [
+  self.location.hostname,
+  'unpkg.com',
+  'fonts.gstatic.com',
+  'fonts.googleapis.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
+}
+
+/**
+ *  @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 */})
+    );
+  }
+});

src/core/fetch/ajax.js

@@ -2,7 +2,6 @@ import progressbar from '../render/progressbar'
 import { noop } from '../util/core'
 
 const cache = {}
-const RUN_VERSION = Date.now()
 
 /**
  * Simple ajax get
@@ -16,8 +15,6 @@ export function get (url, hasBar = false) {
     xhr.addEventListener.apply(xhr, arguments)
   }
 
-  url += (/\?(\w+)=/g.test(url) ? '&' : '?') + `v=${RUN_VERSION}`
-
   if (cache[url]) {
     return { then: cb => cb(cache[url]), abort: noop }
   }