Use uglifyjs-webpack-plugin v1 (facebook#3618)

Author: viankakrisna

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

@@ -12,6 +12,7 @@ const autoprefixer = require('autoprefixer');
 const path = require('path');
 const webpack = require('webpack');
 const HtmlWebpackPlugin = require('html-webpack-plugin');
+const UglifyJsPlugin = require('uglifyjs-webpack-plugin');
 const ExtractTextPlugin = require('extract-text-webpack-plugin');
 const ManifestPlugin = require('webpack-manifest-plugin');
 const InterpolateHtmlPlugin = require('react-dev-utils/InterpolateHtmlPlugin');
@@ -290,24 +291,31 @@ 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,
-      },
-      mangle: {
-        safari10: true,
-      },
-      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({
+      uglifyOptions: {
+        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,
+        },
+        mangle: {
+          safari10: true,
+        },
+        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,
+        },
       },
+      // Use multi-process parallel running to improve the build speed
+      // Default number of concurrent runs: os.cpus().length - 1
+      parallel: true,
+      // Enable file caching
+      cache: true,
       sourceMap: shouldUseSourceMap,
     }),
     // Note: this won't work without ExtractTextPlugin.extract(..) in `loaders`.

packages/react-scripts/package.json

@@ -53,6 +53,7 @@
     "react-dev-utils": "^5.0.0",
     "style-loader": "0.19.0",
     "sw-precache-webpack-plugin": "0.11.4",
+    "uglifyjs-webpack-plugin": "1.1.4",
     "url-loader": "0.6.2",
     "webpack": "3.8.1",
     "webpack-dev-server": "2.9.4",