Upgrade uglifyjs-webpack-plugin

Author: JohnNilsson

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

@@ -19,6 +19,7 @@ const ManifestPlugin = require('webpack-manifest-plugin');
 const InterpolateHtmlPlugin = require('react-dev-utils/InterpolateHtmlPlugin');
 const SWPrecacheWebpackPlugin = require('sw-precache-webpack-plugin');
 const ModuleScopePlugin = require('react-dev-utils/ModuleScopePlugin');
+const UglifyJsPlugin = require('uglifyjs-webpack-plugin');
 const paths = require('./paths');
 const getClientEnvironment = require('./env');
 
@@ -165,7 +166,7 @@ module.exports = {
           {
             test: /\.(ts|tsx)$/,
             include: paths.appSrc,
-            loader: require.resolve('ts-loader')
+            loader: require.resolve('ts-loader'),
           },
           // The notation here is somewhat confusing.
           // "postcss" loader applies autoprefixer to our CSS.
@@ -272,20 +273,17 @@ module.exports = {
     // Otherwise React will be compiled in the very slow development mode.
     new webpack.DefinePlugin(env.stringified),
     // Minify the code.
-    new webpack.optimize.UglifyJsPlugin({
-      compress: {
-        warnings: false,
-        // Disabled because of an issue with Uglify breaking seemingly valid code:
-        // https://github.com/facebookincubator/create-react-app/issues/2376
-        // Pending further investigation:
-        // https://github.com/mishoo/UglifyJS2/issues/2011
-        comparisons: false,
-      },
-      output: {
-        comments: false,
-        // Turned on because emoji and regex is not minified properly using default
-        // https://github.com/facebookincubator/create-react-app/issues/2488
-        ascii_only: true,
+    new UglifyJsPlugin({
+      //test: /.js($|?)/i //Do we need to change this for ts-loader output?
+      parallel: true,
+      uglifyOptions: {
+        ecma: 6,
+        output: {
+          comments: false,
+          // Turned on because emoji and regex is not minified properly using default
+          // https://github.com/facebookincubator/create-react-app/issues/2488
+          ascii_only: true,
+        },
       },
       sourceMap: shouldUseSourceMap,
     }),

packages/react-scripts/package.json

@@ -38,13 +38,14 @@
     "react-dev-utils": "^3.1.0",
     "react-error-overlay": "^1.0.10",
     "style-loader": "0.18.2",
+    "sw-precache-webpack-plugin": "0.11.4",
     "ts-jest": "^20.0.7",
     "ts-loader": "^2.2.1",
     "tslint": "^5.2.0",
     "tslint-loader": "^3.5.3",
     "tslint-react": "^3.0.0",
     "typescript": "~2.4.0",
-    "sw-precache-webpack-plugin": "0.11.4",
+    "uglifyjs-webpack-plugin": "^1.0.0-beta.2",
     "url-loader": "0.5.9",
     "webpack": "3.5.1",
     "webpack-dev-server": "2.7.1",