Use terser for minification (#5083)

Fixes #5021

build/webpack.js

@@ -19,6 +19,7 @@ import ChunkNamesPlugin from './webpack/plugins/chunk-names-plugin'
 import { ReactLoadablePlugin } from './webpack/plugins/react-loadable-plugin'
 import {SERVER_DIRECTORY, NEXT_PROJECT_ROOT, NEXT_PROJECT_ROOT_NODE_MODULES, NEXT_PROJECT_ROOT_DIST, DEFAULT_PAGES_DIR, REACT_LOADABLE_MANIFEST, CLIENT_STATIC_FILES_RUNTIME_WEBPACK, CLIENT_STATIC_FILES_RUNTIME_MAIN} from '../lib/constants'
 import AutoDllPlugin from 'autodll-webpack-plugin'
+import TerserPlugin from 'terser-webpack-plugin'
 
 // The externals config makes sure that
 // on the server side when modules are
@@ -81,6 +82,13 @@ function optimizationConfig ({dir, dev, isServer, totalPages}) {
     return config
   }
 
+  // Terser is a better uglifier
+  config.minimizer = [new TerserPlugin({
+    parallel: true,
+    sourceMap: false,
+    cache: true
+  })]
+
   // Only enabled in production
   // This logic will create a commons bundle
   // with modules that are used in 50% of all pages

flow-typed/npm/terser-webpack-plugin_vx.x.x.js

@@ -0,0 +1,60 @@
+// flow-typed signature: 7f0a5671a6d757d5e9f880e207a37572
+// flow-typed version: <<STUB>>/terser-webpack-plugin_v1.0.2/flow_v0.73.0
+
+/**
+ * This is an autogenerated libdef stub for:
+ *
+ *   'terser-webpack-plugin'
+ *
+ * Fill this stub out by replacing all the `any` types.
+ *
+ * Once filled out, we encourage you to share your work with the
+ * community by sending a pull request to:
+ * https://github.com/flowtype/flow-typed
+ */
+
+declare module 'terser-webpack-plugin' {
+  declare module.exports: any;
+}
+
+/**
+ * We include stubs for each file inside this npm package in case you need to
+ * require those files directly. Feel free to delete any files that aren't
+ * needed.
+ */
+declare module 'terser-webpack-plugin/dist/cjs' {
+  declare module.exports: any;
+}
+
+declare module 'terser-webpack-plugin/dist/index' {
+  declare module.exports: any;
+}
+
+declare module 'terser-webpack-plugin/dist/minify' {
+  declare module.exports: any;
+}
+
+declare module 'terser-webpack-plugin/dist/TaskRunner' {
+  declare module.exports: any;
+}
+
+declare module 'terser-webpack-plugin/dist/worker' {
+  declare module.exports: any;
+}
+
+// Filename aliases
+declare module 'terser-webpack-plugin/dist/cjs.js' {
+  declare module.exports: $Exports<'terser-webpack-plugin/dist/cjs'>;
+}
+declare module 'terser-webpack-plugin/dist/index.js' {
+  declare module.exports: $Exports<'terser-webpack-plugin/dist/index'>;
+}
+declare module 'terser-webpack-plugin/dist/minify.js' {
+  declare module.exports: $Exports<'terser-webpack-plugin/dist/minify'>;
+}
+declare module 'terser-webpack-plugin/dist/TaskRunner.js' {
+  declare module.exports: $Exports<'terser-webpack-plugin/dist/TaskRunner'>;
+}
+declare module 'terser-webpack-plugin/dist/worker.js' {
+  declare module.exports: $Exports<'terser-webpack-plugin/dist/worker'>;
+}

package.json

@@ -106,6 +106,7 @@
     "source-map": "0.5.7",
     "strip-ansi": "3.0.1",
     "styled-jsx": "3.0.3-canary.0",
+    "terser-webpack-plugin": "1.0.2",
     "unfetch": "3.0.0",
     "url": "0.11.0",
     "webpack": "4.17.1",