fix: use custom terser-webpack-plugin setup

Cherry-picked from and closes #131.

lib/webpack/webpack.config.base.js

@@ -65,16 +65,55 @@ module.exports = (api, config, type) => {
 
   // No need to minimize in server or dev mode
   if (type === 'client' && !api.options.dev && api.config.minimize !== false) {
-    // TODO: is there a simpler way to pull default minimizer setup without copy/pasting it?
-    const defaulter = new webpack.WebpackOptionsDefaulter()
-    const minimizer = defaulter.defaults['optimization.minimizer'](
-      config.toConfig()
-    )
     config.merge({
       optimization: {
         minimize: true,
         minimizer: [
-          ...minimizer,
+          {
+            apply(compiler) {
+              const TerserPlugin = require('terser-webpack-plugin')
+              new TerserPlugin({
+                cache: true,
+                parallel: true,
+                sourceMap: config.get('devtool') !== false,
+                terserOptions: {
+                  parse: {
+                    // we want terser to parse ecma 8 code. However, we don't want it
+                    // to apply any minfication steps that turns valid ecma 5 code
+                    // into invalid ecma 5 code. This is why the 'compress' and 'output'
+                    // sections only apply transformations that are ecma 5 safe
+                    // https://github.com/facebook/create-react-app/pull/4234
+                    ecma: 8
+                  },
+                  compress: {
+                    ecma: 5,
+                    warnings: false,
+                    // Disabled because of an issue with Uglify breaking seemingly valid code:
+                    // https://github.com/facebook/create-react-app/issues/2376
+                    // Pending further investigation:
+                    // https://github.com/mishoo/UglifyJS2/issues/2011
+                    comparisons: false,
+                    // Disabled because of an issue with Terser breaking valid code:
+                    // https://github.com/facebook/create-react-app/issues/5250
+                    // Pending futher investigation:
+                    // https://github.com/terser-js/terser/issues/120
+                    // Fixed in terser 3.10.7 which is not yet pulled by terser-webpack-plugin
+                    inline: 2
+                  },
+                  mangle: {
+                    safari10: true
+                  },
+                  output: {
+                    ecma: 5,
+                    comments: false,
+                    // Turned on because emoji and regex is not minified properly using default
+                    // https://github.com/facebook/create-react-app/issues/2488
+                    ascii_only: true // eslint-disable-line camelcase
+                  }
+                }
+              }).apply(compiler)
+            }
+          },
           {
             apply(compiler) {
               // eslint-disable-next-line import/no-extraneous-dependencies
@@ -219,7 +258,7 @@ module.exports = (api, config, type) => {
     applyLoaders(normalRule, false)
 
     function applyLoaders(rule, modules) {
-      const sourceMap = !isProd
+      const sourceMap = config.get('devtool') !== false
 
       if (extract) {
         if (type === 'client') {

package.json

@@ -71,6 +71,7 @@
     "register-service-worker": "^1.2.0",
     "serialize-javascript": "^1.4.0",
     "serve-static": "^1.13.2",
+    "terser-webpack-plugin": "^1.1.0",
     "time-fix-plugin": "^2.0.4",
     "url-loader": "^1.1.0",
     "vue": "^2.5.16",