feat: Add a polyfill for Promise and fetch

Author: halfzebra

config/polyfills.js

@@ -0,0 +1,16 @@
+'use strict';
+
+if (typeof Promise === 'undefined') {
+  // Rejection tracking prevents a common issue where React gets into an
+  // inconsistent state due to an error, but it gets swallowed by a Promise,
+  // and the user has no idea what causes React's erratic future behavior.
+  require('promise/lib/rejection-tracking').enable();
+  window.Promise = require('promise/lib/es6-extensions.js');
+}
+
+// fetch() polyfill for making API calls.
+require('whatwg-fetch');
+
+// Object.assign() is commonly used with React.
+// It will use the native implementation if it's present and isn't buggy.
+Object.assign = require('object-assign');

config/webpack.config.prod.js

@@ -77,7 +77,7 @@ module.exports = {
   // You can exclude the *.map files from the build during deployment.
   devtool: shouldUseSourceMap ? 'source-map' : false,
   // In production, we only want to load the polyfills and the app code.
-  entry: [/*require.resolve('./polyfills'),*/ paths.appIndexJs],
+  entry: [require.resolve('./polyfills'), paths.appIndexJs],
   output: {
     // The build folder.
     path: paths.appBuild,
@@ -256,10 +256,8 @@ module.exports = {
       }
     ]
   },
-
   plugins: [
-    new webpack.DefinePlugin(env.stringified),
-
+    // Generates an `index.html` file with the <script> injected.
     new HtmlWebpackPlugin({
       inject: true,
       template: paths.appHtml,
@@ -291,8 +289,8 @@ module.exports = {
     new MiniCssExtractPlugin({
       // Options similar to the same options in webpackOptions.output
       // both options are optional
-      filename: 'static/js/[name].[chunkhash:8].css',
-      chunkFilename: 'static/js/[name].[chunkhash:8].chunk.css'
+      filename: 'static/css/[name].[contenthash:8].css',
+      chunkFilename: 'static/css/[name].[contenthash:8].chunk.css',
     }),
     // Generate a manifest file which contains a mapping of all asset filenames
     // to their corresponding output file so that tools can pick it up without
@@ -301,7 +299,6 @@ module.exports = {
       fileName: 'asset-manifest.json',
       publicPath: publicPath
     }),
-
     // Generate a service worker script that will precache, and keep up to date,
     // the HTML & assets that are part of the Webpack build.
     new SWPrecacheWebpackPlugin({