programcsharp
diff --git a/‎streaming-service-worker/client/sw.js
Lines changed: 97 additions & 0 deletions b/‎streaming-service-worker/client/sw.js
Lines changed: 97 additions & 0 deletions
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+const toCache = require('static-to-cache')();
+const version = require('static-version')();
+const revGet = require('static-rev-get');
+
+const staticCacheName = `static-${version}`;
+
+addEventListener('install', event => {
+  skipWaiting();
+
+  event.waitUntil(async function () {
+    const cache = await caches.open(staticCacheName);
+    await cache.addAll(toCache);
+  }());
+});
+
+addEventListener('activate', event => {
+  event.waitUntil(async function () {
+    const keys = await caches.keys();
+    await Promise.all(
+      keys.map(key => {
+        if (key !== staticCacheName) return caches.delete(key);
+      })
+    );
+  }());
+});
+
+class IdentityStream {
+  constructor() {
+    let readableController;
+    let writableController;
+
+    this.readable = new ReadableStream({
+      start(controller) {
+        readableController = controller;
+      },
+      cancel(reason) {
+        writableController.error(reason);
+      }
+    });
+
+    this.writable = new WritableStream({
+      start(controller) {
+        writableController = controller;
+      },
+      write(chunk) {
+        readableController.enqueue(chunk);
+      },
+      close() {
+        readableController.close();
+      },
+      abort(reason) {
+        readableController.error(reason);
+      }
+    });
+  }
+}
+
+async function streamArticle(event, url) {
+  const includeUrl = new URL(url);
+  includeUrl.pathname += 'include';
+
+  const parts = [
+    caches.match(revGet('/static/shell-start.html')),
+    fetch(includeUrl).catch(() => caches.match(revGet('/static/offline-inc.html'))),
+    caches.match(revGet('/static/shell-end.html'))
+  ];
+
+  const identity = new IdentityStream();
+
+  event.waitUntil(async function() {
+    for (const responsePromise of parts) {
+      const response = await responsePromise;
+      await response.body.pipeTo(identity.writable, { preventClose: true });
+    }
+    identity.writable.getWriter().close();
+  }());
+
+  return new Response(identity.readable, {
+    headers: { 'Content-Type': 'text/html; charset=utf-8' }
+  });
+}
+
+addEventListener('fetch', event => {
+  if (event.request.method !== 'GET') return;
+  const url = new URL(event.request.url);
+
+  event.respondWith(async function () {
+    if (url.origin === location.origin && /^\/\d{4}\/[\w-]+\/$/.test(url.pathname)) {
+      return streamArticle(event, url);
+    }
+
+    const cachedReponse = await caches.match(event.request);
+    if (cachedReponse) return cachedReponse;
+
+    return await fetch(event.request);
+  }());
+});