facebook · iansu · Jul 22, 2020 · Jun 11, 2020 · Jun 11, 2020 · Jun 11, 2020
diff --git a/docusaurus/docs/making-a-progressive-web-app.md b/docusaurus/docs/making-a-progressive-web-app.md
@@ -6,9 +6,15 @@ title: Making a Progressive Web App
 The production build has all the tools necessary to generate a first-class
 [Progressive Web App](https://developers.google.com/web/progressive-web-apps/),
 but **the offline/cache-first behavior is opt-in only**. By default,
-the build process will generate a service worker file, but it will not be
+the build process will compile a service worker file, but it will not be
 registered, so it will not take control of your production web app.
 
+If you know that you won't be using service workers, you can speed up the build
+process by removing the
+[`src/service-worker.js`](https://github.com/facebook/create-react-app/blob/master/packages/cra-template/template/src/service-worker.js)
+file from your local project. This will skip the step that compiles your
+service worker at build time.
+
 In order to opt-in to the offline-first behavior, developers should look for the
 following in their [`src/index.js`](https://github.com/facebook/create-react-app/blob/master/packages/cra-template/template/src/index.js) file:
 
@@ -34,14 +40,43 @@ However, they [can make debugging deployments more challenging](https://github.c
 
 The [`workbox-webpack-plugin`](https://developers.google.com/web/tools/workbox/modules/workbox-webpack-plugin)
 is integrated into production configuration,
-and it will take care of generating a service worker file that will automatically
-precache all of your local assets and keep them up to date as you deploy updates.
+and it will take care of compiling a service worker file that will automatically
+precache all of your `webpack`-generated assets and keep them up to date as you
+deploy updates.
 The service worker will use a [cache-first strategy](https://developers.google.com/web/fundamentals/instant-and-offline/offline-cookbook/#cache-falling-back-to-network)
-for handling all requests for local assets, including
+for handling all requests for `webpack`-generated assets, including
 [navigation requests](https://developers.google.com/web/fundamentals/primers/service-workers/high-performance-loading#first_what_are_navigation_requests)
 for your HTML, ensuring that your web app is consistently fast, even on a slow
 or unreliable network.
 
+Note: Resources that are not generated by `webpack`, such as static files that are
+copied over from your local
+[`public/` directory](https://github.com/facebook/create-react-app/blob/master/packages/cra-template/template/public/)
+or third-party resources, will not be precached. You can optionally set up Workbox
+[routes](https://developers.google.com/web/tools/workbox/guides/route-requests)
+to apply the runtime caching strategy of your choice to those resources.
+
+## Customization
+
+Starting with Create React App 4, you have full control over customizing the
+logic in this service worker, by making changes to
+[`src/service-worker.js`](https://github.com/facebook/create-react-app/blob/master/packages/cra-template/template/src/service-worker.js).
+You can use
+[additional modules](https://developers.google.com/web/tools/workbox/modules)
+from the Workbox project, add in a push notification library, or remove some of
+the default caching logic. The one requirement is that you keep
+`self.__WB_MANIFEST` somewhere in your file, as the Workbox compilation plugin
+checks for this value when generating a manifest of URLs to precache. If you
+would prefer not to use precaching, you can just assign `self.__WB_MANIFEST`
+to a variable that will be ignored, like:
+
+```js
+// eslint-disable-next-line no-restricted-globals
+const ignored = self.__WB_MANIFEST;
+
+// Your custom service worker code goes here.
+```
+
 ## Offline-First Considerations
 
 If you do decide to opt-in to service worker registration, please take the
@@ -88,7 +123,8 @@ following into account:
 
 1. By default, the generated service worker file will not intercept or cache any
    cross-origin traffic, like HTTP [API requests](integrating-with-an-api-backend.md),
-   images, or embeds loaded from a different domain.
+   images, or embeds loaded from a different domain. Starting with Create
+   React App 4, this can be customized, as explained above.
 
 ## Progressive Web App Metadata
 

diff --git a/packages/cra-template-typescript/template/src/index.tsx b/packages/cra-template-typescript/template/src/index.tsx
@@ -2,7 +2,7 @@ import React from 'react';
 import ReactDOM from 'react-dom';
 import './index.css';
 import App from './App';
-import * as serviceWorker from './serviceWorker';
+import * as serviceWorkerRegistration from './serviceWorkerRegistration';
 import reportWebVitals from './reportWebVitals';
 
 ReactDOM.render(
@@ -15,7 +15,7 @@ ReactDOM.render(
 // If you want your app to work offline and load faster, you can change
 // unregister() to register() below. Note this comes with some pitfalls.
 // Learn more about service workers: https://cra.link/PWA
-serviceWorker.unregister();
+serviceWorkerRegistration.unregister();
 
 // If you want to start measuring performance in your app, pass a function
 // to log results (for example: reportWebVitals(console.log))

diff --git a/packages/cra-template-typescript/template/src/service-worker.ts b/packages/cra-template-typescript/template/src/service-worker.ts
@@ -0,0 +1,80 @@
+/// <reference lib="webworker" />
+/* eslint-disable no-restricted-globals */
+
+// This service worker can be customized!
+// See https://developers.google.com/web/tools/workbox/modules
+// for the list of available Workbox modules, or add any other
+// code you'd like.
+// You can also remove this file if you'd prefer not to use a
+// service worker, and the Workbox build step will be skipped.
+
+import { clientsClaim } from 'workbox-core';
+import { ExpirationPlugin } from 'workbox-expiration';
+import { precacheAndRoute, createHandlerBoundToURL } from 'workbox-precaching';
+import { registerRoute } from 'workbox-routing';
+import { StaleWhileRevalidate} from 'workbox-strategies';
+
+declare const self: ServiceWorkerGlobalScope;
+
+clientsClaim();
+
+// Precache all of the assets generated by your build process.
+// Their URLs are injected into the manifest variable below.
+// This variable must be present somewhere in your service worker file,
+// even if you decide not to use precaching. See https://cra.link/PWA
+precacheAndRoute(self.__WB_MANIFEST);
+
+// Set up App Shell-style routing, so that all navigation requests
+// are fulfilled with your index.html shell. Learn more at
+// https://developers.google.com/web/fundamentals/architecture/app-shell
+const fileExtensionRegexp = new RegExp('/[^/?]+\\.[^/]+$');
+registerRoute(
+  // Return false to exempt requests from being fulfilled by index.html.
+  ({ request, url }: { request: Request; url: URL }) => {
+    // If this isn't a navigation, skip.
+    if (request.mode !== 'navigate') {
+      return false;
+    }
+
+    // If this is a URL that starts with /_, skip.
+    if (url.pathname.startsWith('/_')) {
+      return false;
+    }
+
+    // If this looks like a URL for a resource, because it contains
+    // a file extension, skip.
+    if (url.pathname.match(fileExtensionRegexp)) {
+      return false;
+    }
+
+    // Return true to signal that we want to use the handler.
+    return true;
+  },
+  createHandlerBoundToURL(process.env.PUBLIC_URL + '/index.html')
+);
+
+// An example runtime caching route for requests that aren't handled by the
+// precache, in this case same-origin .png requests like those from in public/
+registerRoute(
+  // Add in any other file extensions or routing criteria as needed.
+  ({url}) => url.origin === self.location.origin && url.pathname.endsWith('.png'),
+  // Customize this strategy as needed, e.g., by changing to CacheFirst.
+  new StaleWhileRevalidate({
+    cacheName: 'images',
+    plugins: [
+      // Ensure that once this runtime cache reaches a maximum size the
+      // least-recently used images are removed.
+      new ExpirationPlugin({maxEntries: 50}),
+    ],
+  }),
+);
+
+// This allows the web app to trigger skipWaiting via
+// registration.waiting.postMessage({type: 'SKIP_WAITING'})
+self.addEventListener('message', event => {
+  if (event.data && event.data.type === 'SKIP_WAITING') {
+    self.skipWaiting();
+  }
+});
+
+// Any other custom service worker logic can go here.
diff --git a/...-typescript/template/src/serviceWorker.ts → ...template/src/serviceWorkerRegistration.ts b/...-typescript/template/src/serviceWorker.ts → ...template/src/serviceWorkerRegistration.ts
diff --git a/packages/cra-template/template/src/index.js b/packages/cra-template/template/src/index.js
@@ -2,7 +2,7 @@ import React from 'react';
 import ReactDOM from 'react-dom';
 import './index.css';
 import App from './App';
-import * as serviceWorker from './serviceWorker';
+import * as serviceWorkerRegistration from './serviceWorkerRegistration';
 import reportWebVitals from './reportWebVitals';
 
 ReactDOM.render(
@@ -15,7 +15,7 @@ ReactDOM.render(
 // If you want your app to work offline and load faster, you can change
 // unregister() to register() below. Note this comes with some pitfalls.
 // Learn more about service workers: https://cra.link/PWA
-serviceWorker.unregister();
+serviceWorkerRegistration.unregister();
 
 // If you want to start measuring performance in your app, pass a function
 // to log results (for example: reportWebVitals(console.log))

diff --git a/packages/cra-template/template/src/service-worker.js b/packages/cra-template/template/src/service-worker.js
@@ -0,0 +1,78 @@
+/* eslint-disable no-restricted-globals */
+
+// This service worker can be customized!
+// See https://developers.google.com/web/tools/workbox/modules
+// for the list of available Workbox modules, or add any other
+// code you'd like.
+// You can also remove this file if you'd prefer not to use a
+// service worker, and the Workbox build step will be skipped.
+
+import { clientsClaim } from 'workbox-core';
+import { ExpirationPlugin } from 'workbox-expiration';
+import { precacheAndRoute, createHandlerBoundToURL } from 'workbox-precaching';
+import { registerRoute } from 'workbox-routing';
+import { StaleWhileRevalidate } from 'workbox-strategies';
+
+clientsClaim();
+
+// Precache all of the assets generated by your build process.
+// Their URLs are injected into the manifest variable below.
+// This variable must be present somewhere in your service worker file,
+// even if you decide not to use precaching. See https://cra.link/PWA
+precacheAndRoute(self.__WB_MANIFEST);
+
+// Set up App Shell-style routing, so that all navigation requests
+// are fulfilled with your index.html shell. Learn more at
+// https://developers.google.com/web/fundamentals/architecture/app-shell
+const fileExtensionRegexp = new RegExp('/[^/?]+\\.[^/]+$');
+registerRoute(
+  // Return false to exempt requests from being fulfilled by index.html.
+  ({ request, url }) => {
+    // If this isn't a navigation, skip.
+    if (request.mode !== 'navigate') {
+      return false;
+    }
+
+    // If this is a URL that starts with /_, skip.
+    if (url.pathname.startsWith('/_')) {
+      return false;
+    }
+
+    // If this looks like a URL for a resource, because it contains
+    // a file extension, skip.
+    if (url.pathname.match(fileExtensionRegexp)) {
+      return false;
+    }
+
+    // Return true to signal that we want to use the handler.
+    return true;
+  },
+  createHandlerBoundToURL(process.env.PUBLIC_URL + '/index.html')
+);
+
+// An example runtime caching route for requests that aren't handled by the
+// precache, in this case same-origin .png requests like those from in public/
+registerRoute(
+  // Add in any other file extensions or routing criteria as needed.
+  ({ url }) =>
+    url.origin === self.location.origin && url.pathname.endsWith('.png'),
+  // Customize this strategy as needed, e.g., by changing to CacheFirst.
+  new StaleWhileRevalidate({
+    cacheName: 'images',
+    plugins: [
+      // Ensure that once this runtime cache reaches a maximum size the
+      // least-recently used images are removed.
+      new ExpirationPlugin({ maxEntries: 50 }),
+    ],
+  })
+);
+
+// This allows the web app to trigger skipWaiting via
+// registration.waiting.postMessage({type: 'SKIP_WAITING'})
+self.addEventListener('message', event => {
+  if (event.data && event.data.type === 'SKIP_WAITING') {
+    self.skipWaiting();
+  }
+});
+
+// Any other custom service worker logic can go here.
diff --git a/...ra-template/template/src/serviceWorker.js → ...template/src/serviceWorkerRegistration.js b/...ra-template/template/src/serviceWorker.js → ...template/src/serviceWorkerRegistration.js
diff --git a/packages/react-scripts/config/paths.js b/packages/react-scripts/config/paths.js
@@ -72,6 +72,7 @@ module.exports = {
   testsSetup: resolveModule(resolveApp, 'src/setupTests'),
   proxySetup: resolveApp('src/setupProxy.js'),
   appNodeModules: resolveApp('node_modules'),
+  swSrc: resolveModule(resolveApp, 'src/service-worker'),
   publicUrlOrPath,
 };
 
@@ -94,6 +95,7 @@ module.exports = {
   testsSetup: resolveModule(resolveApp, 'src/setupTests'),
   proxySetup: resolveApp('src/setupProxy.js'),
   appNodeModules: resolveApp('node_modules'),
+  swSrc: resolveModule(resolveApp, 'src/service-worker'),
   publicUrlOrPath,
   // These properties only exist before ejecting:
   ownPath: resolveOwn('.'),
@@ -129,6 +131,7 @@ if (
     testsSetup: resolveModule(resolveOwn, `${templatePath}/src/setupTests`),
     proxySetup: resolveOwn(`${templatePath}/src/setupProxy.js`),
     appNodeModules: resolveOwn('node_modules'),
+    swSrc: resolveModule(resolveOwn, `${templatePath}/src/service-worker`),
     publicUrlOrPath,
     // These properties only exist before ejecting:
     ownPath: resolveOwn('.'),

diff --git a/packages/react-scripts/config/webpack.config.js b/packages/react-scripts/config/webpack.config.js
@@ -60,6 +60,9 @@ const imageInlineSizeLimit = parseInt(
 // Check if TypeScript is setup
 const useTypeScript = fs.existsSync(paths.appTsConfig);
 
+// Get the path to the uncompiled service worker (if it exists).
+const swSrc = paths.swSrc;
+
 // style files regexes
 const cssRegex = /\.css$/;
 const cssModuleRegex = /\.module\.css$/;
@@ -692,20 +695,11 @@ module.exports = function (webpackEnv) {
       // Generate a service worker script that will precache, and keep up to date,
       // the HTML & assets that are part of the webpack build.
       isEnvProduction &&
-        new WorkboxWebpackPlugin.GenerateSW({
-          clientsClaim: true,
-          exclude: [/\.map$/, /asset-manifest\.json$/],
-          importWorkboxFrom: 'cdn',
-          navigateFallback: paths.publicUrlOrPath + 'index.html',
-          navigateFallbackBlacklist: [
-            // Exclude URLs starting with /_, as they're likely an API call
-            new RegExp('^/_'),
-            // Exclude any URLs whose last part seems to be a file extension
-            // as they're likely a resource and not a SPA route.
-            // URLs containing a "?" character won't be blacklisted as they're likely
-            // a route with query params (e.g. auth callbacks).
-            new RegExp('/[^/?]+\\.[^/]+$'),
-          ],
+        fs.existsSync(swSrc) &&
+        new WorkboxWebpackPlugin.InjectManifest({
+          swSrc,
+          dontCacheBustURLsMatching: /\.[0-9a-f]{8}\./,
+          exclude: [/\.map$/, /asset-manifest\.json$/, /LICENSE/],
         }),
       // TypeScript type checking
       useTypeScript &&

diff --git a/packages/react-scripts/package.json b/packages/react-scripts/package.json
@@ -82,7 +82,7 @@
     "webpack": "4.43.0",
     "webpack-dev-server": "3.11.0",
     "webpack-manifest-plugin": "2.2.0",
-    "workbox-webpack-plugin": "4.3.1"
+    "workbox-webpack-plugin": "5.1.3"
   },
   "devDependencies": {
     "react": "^16.12.0",