[vue-loader] allow using builtin extractCSS functionality

This option is disabled by default and won't affect exiting users.
However users can easily enable this option using `nuxt.build.extractCSS`

Implementation is according to:
- https://github.com/vuejs/vue-loader/tree/master/docs/en/configurations
- https://ssr.vuejs.org/en/css.html
- https://github.com/vuejs/vue-hackernews-2.0/tree/master/build

examples/custom-build/nuxt.config.js

@@ -1,6 +1,7 @@
 module.exports = {
   build: {
     filenames: {
+        css: 'styles.[chunkhash].css',         // default: common.[chunkhash].css
         manifest: 'manifest.[hash].js',   // default: manifest.[hash].js
         vendor: 'vendor.[hash].js',       // default: vendor.bundle.[hash].js
         app: 'app.[chunkhash].js'         // default: nuxt.bundle.[chunkhash].js

lib/build.js

@@ -51,6 +51,7 @@ const defaults = {
   analyze: false,
   publicPath: '/_nuxt/',
   filenames: {
+    css: 'common.[chunkhash].css',
     manifest: 'manifest.[hash].js',
     vendor: 'vendor.bundle.[hash].js',
     app: 'nuxt.bundle.[chunkhash].js'

lib/webpack/base.config.js

@@ -4,6 +4,8 @@ import vueLoaderConfig from './vue-loader.config'
 import { defaults } from 'lodash'
 import { join } from 'path'
 import { isUrl, urlJoin } from '../utils'
+import { styleLoader, extractStyles } from './helpers'
+import ExtractTextPlugin from 'extract-text-webpack-plugin'
 
 /*
 |--------------------------------------------------------------------------
@@ -71,15 +73,21 @@ export default function ({ isClient, isServer }) {
             cacheDirectory: !!this.dev
           })
         },
-        { test: /\.css$/, loader: 'vue-style-loader!css-loader' },
+        { test: /\.css$/, use: styleLoader.call(this, 'css') },
-        { test: /\.less$/, loader: 'vue-style-loader!css-loader!less-loader' },
+        { test: /\.less$/, use: styleLoader.call(this, 'less', 'less-loader') },
-        { test: /\.sass$/, loader: 'vue-style-loader!css-loader!sass-loader?indentedSyntax' },
+        { test: /\.sass$/, use: styleLoader.call(this, 'sass', 'sass-loader?indentedSyntax') },
-        { test: /\.scss$/, loader: 'vue-style-loader!css-loader!sass-loader' },
+        { test: /\.scss$/, use: styleLoader.call(this, 'sass', 'sass-loader') },
-        { test: /\.styl(us)?$/, loader: 'vue-style-loader!css-loader!stylus-loader' }
+        { test: /\.styl(us)?$/, use: styleLoader.call(this, 'stylus', 'stylus-loader') }
       ]
     },
     plugins: this.options.build.plugins
   }
+  // CSS extraction
+  if (extractStyles.call(this)) {
+    config.plugins.push(
+      new ExtractTextPlugin({filename: this.options.build.filenames.css})
+    )
+  }
   // Add nuxt build loaders (can be configured in nuxt.config.js)
   config.module.rules = config.module.rules.concat(this.options.build.loaders)
   // Return config

lib/webpack/client.config.js

@@ -3,12 +3,14 @@
 import { each, defaults } from 'lodash'
 import webpack from 'webpack'
 import VueSSRClientPlugin from 'vue-server-renderer/client-plugin'
+import ExtractTextPlugin from 'extract-text-webpack-plugin'
 import HTMLPlugin from 'html-webpack-plugin'
 import FriendlyErrorsWebpackPlugin from 'friendly-errors-webpack-plugin'
 import ProgressBarPlugin from 'progress-bar-webpack-plugin'
 import { BundleAnalyzerPlugin } from 'webpack-bundle-analyzer'
 import OfflinePlugin from 'offline-plugin'
 import base from './base.config.js'
+import { extractStyles } from './helpers'
 import { resolve } from 'path'
 
 /*
@@ -55,9 +57,18 @@ export default function () {
     // Extract vendor chunks for better caching
     new webpack.optimize.CommonsChunkPlugin({
       name: 'vendor',
-      filename: this.options.build.filenames.vendor
+      filename: this.options.build.filenames.vendor,
+      minChunks (module) {
+        // A module is extracted into the vendor chunk when...
+        return (
+          // If it's inside node_modules
+          /node_modules/.test(module.context) &&
+          // Do not externalize if the request is a CSS file
+          !/\.css$/.test(module.request)
+        )
+      }
     }),
-    // Extract manifest
+    // Extract webpack runtime & manifest
     new webpack.optimize.CommonsChunkPlugin({
       name: 'manifest',
       minChunks: Infinity,
@@ -68,6 +79,7 @@ export default function () {
       template: this.options.appTemplatePath,
       inject: false // <- Resources will be injected using vue server renderer
     }),
+    // Generate client manifest json
     new VueSSRClientPlugin({
       filename: 'client-manifest.json'
     })

lib/webpack/helpers.js

@@ -0,0 +1,15 @@
+import ExtractTextPlugin from 'extract-text-webpack-plugin'
+
+export function extractStyles(ext) {
+  return !this.dev && !!this.options.build.extractCSS && this.options.build.extractCSS[ext] !== false
+}
+
+export function styleLoader(ext, loader = []) {
+  if (!extractStyles.call(this, ext)) {
+    return ['vue-style-loader', 'css-loader'].concat(loader)
+  }
+  return ExtractTextPlugin.extract({
+    use: ['css-loader?minimize'].concat(loader),
+    fallback: 'vue-style-loader'
+  })
+}

lib/webpack/vue-loader.config.js

@@ -1,6 +1,7 @@
 'use strict'
 
 import { defaults } from 'lodash'
+import { extractStyles, styleLoader } from './helpers'
 
 export default function ({ isClient }) {
   let babelOptions = JSON.stringify(defaults(this.options.build.babel, {
@@ -8,18 +9,21 @@ export default function ({ isClient }) {
     babelrc: false,
     cacheDirectory: !!this.dev
   }))
+
+  // https://github.com/vuejs/vue-loader/blob/master/docs/en/configurations
   let config = {
     postcss: this.options.build.postcss,
     loaders: {
       'js': 'babel-loader?' + babelOptions,
-      'css': 'vue-style-loader!css-loader',
+      'css': styleLoader.call(this, 'css'),
-      'less': 'vue-style-loader!css-loader!less-loader',
+      'less': styleLoader.call(this, 'less', 'less-loader'),
-      'sass': 'vue-style-loader!css-loader!sass-loader?indentedSyntax',
+      'sass': styleLoader.call(this, 'sass', 'sass-loader?indentedSyntax'),
-      'scss': 'vue-style-loader!css-loader!sass-loader',
+      'scss': styleLoader.call(this, 'sass', 'scss-loader'),
-      'stylus': 'vue-style-loader!css-loader!stylus-loader',
+      'stylus': styleLoader.call(this, 'stylus', 'stylus-loader'),
-      'styl': 'vue-style-loader!css-loader!stylus-loader'
+      'styl': styleLoader.call(this, 'stylus', 'stylus-loader')
     },
-    preserveWhitespace: false
+    preserveWhitespace: false,
+    extractCSS: extractStyles.call(this, 'vue')
   }
   // Return the config
   return config

package.json

@@ -62,6 +62,7 @@
     "compression": "^1.6.2",
     "css-loader": "^0.28.0",
     "debug": "^2.6.6",
+    "extract-text-webpack-plugin": "^2.1.0",
     "file-loader": "^0.11.1",
     "friendly-errors-webpack-plugin": "^1.6.1",
     "fs-extra": "^3.0.0",