Revert "Remove the navigateFallback behavior from the generated service worker (facebook#3419)"

This reverts commit b6aebb9.

# Conflicts:
#	packages/react-scripts/template/README.md

Author: piotr-cz

packages/react-scripts/config/webpack.config.prod.js

@@ -442,12 +442,13 @@ module.exports = {
         console.log(message);
       },
       minify: true,
+      // For unknown URLs, fallback to the index page
+      navigateFallback: publicUrl + '/index.html',
+      // Ignores URLs starting from /__ (useful for Firebase):
+      // https://github.com/facebookincubator/create-react-app/issues/2237#issuecomment-302693219
+      navigateFallbackWhitelist: [/^(?!\/__).*/],
       // Don't precache sourcemaps (they're large) and build asset manifest:
       staticFileGlobsIgnorePatterns: [/\.map$/, /asset-manifest\.json$/],
-      // `navigateFallback` and `navigateFallbackWhitelist` are disabled by default; see
-      // https://github.com/facebookincubator/create-react-app/blob/master/packages/react-scripts/template/README.md#service-worker-considerations
-      // navigateFallback: publicUrl + '/index.html',
-      // navigateFallbackWhitelist: [/^(?!\/__).*/],
     }),
     // Moment.js is an extremely popular library that bundles large locale files
     // by default due to how Webpack interprets its code. This is a practical

packages/react-scripts/template/README.md

@@ -83,7 +83,6 @@ You can find the most recent version of this guide [here](https://github.com/fac
   - [Static Server](#static-server)
   - [Other Solutions](#other-solutions)
   - [Serving Apps with Client-Side Routing](#serving-apps-with-client-side-routing)
-    - [Service Worker Considerations](#service-worker-considerations)
   - [Building for Relative Paths](#building-for-relative-paths)
   - [Azure](#azure)
   - [Firebase](#firebase)
@@ -1839,14 +1838,8 @@ 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.
 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
-[navigation requests](https://developers.google.com/web/fundamentals/primers/service-workers/high-performance-loading#first_what_are_navigation_requests)
-for `/` and `/index.html`, ensuring that your web app is consistently fast, even
-on a slow or unreliable network.
-
->Note: If you are using the `pushState` history API and want to enable
-cache-first navigations for URLs other than `/` and `/index.html`, please
-[follow these steps](#service-worker-considerations).
+for handling all requests for local assets, including the initial HTML, ensuring
+that your web app is reliably fast, even on a slow or unreliable network.
 
 ### Opting Out of Caching
 
@@ -2049,27 +2042,20 @@ If you’re using [Apache Tomcat](http://tomcat.apache.org/), you need to follow
 
 Now requests to `/todos/42` will be handled correctly both in development and in production.
 
-When users install your app to the homescreen of their device the default configuration will make a shortcut to `/`. This may not work if you don't use a client-side router and expect the app to be served from `/index.html`. In this case, the web app manifest at [`public/manifest.json`](public/manifest.json) and change `start_url` to `./index.html`.
-
-### Service Worker Considerations
-
-[Navigation requests](https://developers.google.com/web/fundamentals/primers/service-workers/high-performance-loading#first_what_are_navigation_requests)
-for URLs like `/todos/42` will not be intercepted by the
-[service worker](https://developers.google.com/web/fundamentals/getting-started/primers/service-workers)
-created by the production build. Navigations for those URLs will always
-require a network connection, as opposed to navigations for `/` and
-`/index.html`, both of which will be served from the cache by the service worker
-and work without requiring a network connection.
-
-If you are using the `pushState` history API and would like to enable service
-worker support for navigations to URLs like `/todos/42`, you need to
-[`npm eject`](#npm-run-eject) and enable the [`navigateFallback`](https://github.com/GoogleChrome/sw-precache#navigatefallback-string)
+On a production build, and in a browser that supports [service workers](https://developers.google.com/web/fundamentals/getting-started/primers/service-workers),
+the service worker will automatically handle all navigation requests, like for
+`/todos/42`, by serving the cached copy of your `index.html`. This
+service worker navigation routing can be configured or disabled by
+[`eject`ing](#npm-run-eject) and then modifying the
+[`navigateFallback`](https://github.com/GoogleChrome/sw-precache#navigatefallback-string)
 and [`navigateFallbackWhitelist`](https://github.com/GoogleChrome/sw-precache#navigatefallbackwhitelist-arrayregexp)
 options of the `SWPreachePlugin` [configuration](../config/webpack.config.prod.js).
 
->Note: This is a [change in default behavior](https://github.com/facebookincubator/create-react-app/issues/3248),
-as earlier versions of `create-react-app` shipping with `navigateFallback`
-enabled by default.
+When users install your app to the homescreen of their device the default configuration will make a shortcut to `/index.html`. This may not work for client-side routers which expect the app to be served from `/`. Edit the web app manifest at [`public/manifest.json`](public/manifest.json) and change `start_url` to match the required URL scheme, for example:
+
+```js
+  "start_url": ".",
+```
 
 ### Building for Relative Paths