perf(SSR): bundle with native async/await and less transpilations

lib/builder/builder.js

@@ -128,19 +128,6 @@ export default class Builder {
     // Call before hook
     await this.nuxt.callHook('build:before', this, this.options.build)
 
-    // Babel options
-    this.babelOptions = _.defaults(this.options.build.babel, {
-      babelrc: false,
-      cacheDirectory: !!this.options.dev
-    })
-    if (!this.babelOptions.babelrc && !this.babelOptions.presets) {
-      this.babelOptions.presets = [
-        [require.resolve('babel-preset-vue-app'), {
-          targets: { ie: 9, uglify: true }
-        }]
-      ]
-    }
-
     // Map postcss plugins into instances on object mode once
     if (isPureObject(this.options.build.postcss)) {
       if (isPureObject(this.options.build.postcss.plugins)) {
@@ -193,6 +180,30 @@ export default class Builder {
     return this
   }
 
+  getBabelOptions({ isServer }) {
+    const options = _.defaults({}, {
+      babelrc: false,
+      cacheDirectory: !!this.options.dev
+    }, this.options.build.babel)
+
+    if (typeof options.presets === 'function') {
+      options.presets = options.presets({ isServer })
+    }
+
+    if (!options.babelrc && !options.presets) {
+      options.presets = [
+        [
+          require.resolve('babel-preset-vue-app'),
+          {
+            targets: isServer ? { node: '8.0.0' } : { ie: 9, uglify: true }
+          }
+        ]
+      ]
+    }
+
+    return options
+  }
+
   async generateRoutesAndFiles() {
     debug('Generating files...')
     // -- Templates --

lib/builder/webpack/base.config.js

@@ -14,7 +14,7 @@ import WarnFixPlugin from './warnfix-plugin'
 | webpack config files
 |--------------------------------------------------------------------------
 */
-export default function webpackBaseConfig(name) {
+export default function webpackBaseConfig({ name, isServer }) {
   const nodeModulesDir = join(__dirname, '..', 'node_modules')
 
   const config = {
@@ -65,13 +65,13 @@ export default function webpackBaseConfig(name) {
         {
           test: /\.vue$/,
           loader: 'vue-loader',
-          options: this.vueLoader()
+          options: this.vueLoader({ isServer })
         },
         {
           test: /\.js$/,
           loader: 'babel-loader',
           exclude: /node_modules/,
-          options: Object.assign({}, this.babelOptions)
+          options: this.getBabelOptions({ isServer })
         },
         { test: /\.css$/, use: this.styleLoader('css') },
         { test: /\.less$/, use: this.styleLoader('less', 'less-loader') },

lib/builder/webpack/client.config.js

@@ -25,7 +25,7 @@ debug.color = 2 // Force green color
 |--------------------------------------------------------------------------
 */
 export default function webpackClientConfig() {
-  let config = base.call(this, 'client')
+  let config = base.call(this, { name: 'client', isServer: false })
 
   // Entry points
   config.entry.app = resolve(this.options.buildDir, 'client.js')

lib/builder/webpack/server.config.js

@@ -12,7 +12,7 @@ import base from './base.config.js'
 |--------------------------------------------------------------------------
 */
 export default function webpackServerConfig() {
-  let config = base.call(this, 'server')
+  let config = base.call(this, { name: 'server', isServer: true })
 
   // env object defined in nuxt.config.js
   let env = {}

lib/builder/webpack/vue-loader.config.js

@@ -1,4 +1,4 @@
-export default function vueLoader() {
+export default function vueLoader({ isServer }) {
   // https://vue-loader.vuejs.org/en
   const config = {
     postcss: this.options.build.postcss,
@@ -8,7 +8,7 @@ export default function vueLoader() {
     loaders: {
       'js': {
         loader: 'babel-loader',
-        options: Object.assign({}, this.babelOptions)
+        options: this.getBabelOptions({ isServer })
       },
       // Note: do not nest the `postcss` option under `loaders`
       'css': this.styleLoader('css', [], true),