Global CSS Support

packages/next/build/webpack-config.ts

@@ -1,5 +1,7 @@
 import crypto from 'crypto'
 import ForkTsCheckerWebpackPlugin from 'fork-ts-checker-webpack-plugin'
+import MiniCssExtractPlugin from 'mini-css-extract-plugin'
+import OptimizeCssAssetsPlugin from 'optimize-css-assets-webpack-plugin'
 import path from 'path'
 // @ts-ignore: Currently missing types
 import PnpWebpackPlugin from 'pnp-webpack-plugin'
@@ -20,6 +22,7 @@ import {
   SERVER_DIRECTORY,
   SERVERLESS_DIRECTORY,
 } from '../next-server/lib/constants'
+import { findPageFile } from '../server/lib/find-page-file'
 import { WebpackEntrypoints } from './entries'
 import BuildManifestPlugin from './webpack/plugins/build-manifest-plugin'
 import { ChunkGraphPlugin } from './webpack/plugins/chunk-graph-plugin'
@@ -291,6 +294,15 @@ export default async function getBaseWebpackConfig(
       ? 'anonymous'
       : config.crossOrigin
 
+  let customAppFile = await findPageFile(
+    path.join(dir, 'pages'),
+    '/_app',
+    config.pageExtensions
+  )
+  if (customAppFile) {
+    customAppFile = path.resolve(path.join(dir, 'pages', customAppFile))
+  }
+
   let webpackConfig: webpack.Configuration = {
     devtool,
     mode: webpackMode,
@@ -419,11 +431,26 @@ export default async function getBaseWebpackConfig(
         : { name: CLIENT_STATIC_FILES_RUNTIME_WEBPACK },
       minimize: !(dev || isServer),
       minimizer: [
+        // Minify JavaScript
         new TerserPlugin({
           ...terserPluginConfig,
           terserOptions,
         }),
-      ],
+        // Minify CSS
+        config.experimental.css &&
+          new OptimizeCssAssetsPlugin({
+            cssProcessorOptions: {
+              map: {
+                // `inline: false` generates the source map in a separate file.
+                // Otherwise, the CSS file is needlessly large.
+                inline: false,
+                // `annotation: true` appends the `sourceMappingURL` to the end
+                // of the CSS file for DevTools to find them.
+                annotation: true,
+              },
+            },
+          }),
+      ].filter(Boolean),
     },
     recordsPath: path.join(outputPath, 'records.json'),
     context: dir,
@@ -518,6 +545,75 @@ export default async function getBaseWebpackConfig(
           },
           use: defaultLoaders.babel,
         },
+        config.experimental.css &&
+          // Support CSS imports
+          ({
+            test: /\.css$/,
+            issuer: { include: [customAppFile].filter(Boolean) },
+            use: isServer
+              ? // Global CSS is ignored on the server because it's only needed
+                // on the client-side.
+                require.resolve('ignore-loader')
+              : [
+                  // During development we load CSS via JavaScript so we can
+                  // hot reload it without refreshing the page.
+                  dev && require.resolve('style-loader'),
+                  // When building for production we extract CSS into
+                  // separate files.
+                  !dev && {
+                    loader: MiniCssExtractPlugin.loader,
+                    options: {},
+                  },
+
+                  // Resolve CSS `@import`s and `url()`s
+                  {
+                    loader: require.resolve('css-loader'),
+                    options: { importLoaders: 1, sourceMap: !dev },
+                  },
+
+                  // Compile CSS
+                  {
+                    loader: require.resolve('postcss-loader'),
+                    options: {
+                      ident: 'postcss',
+                      plugins: () => [
+                        // Make Flexbox behave like the spec cross-browser.
+                        require('postcss-flexbugs-fixes'),
+                        // Run Autoprefixer and compile new CSS features.
+                        require('postcss-preset-env')({
+                          autoprefixer: {
+                            // Disable legacy flexbox support
+                            flexbox: 'no-2009',
+                          },
+                          // Enable CSS features that have shipped to the
+                          // web platform, i.e. in 2+ browsers unflagged.
+                          stage: 3,
+                        }),
+                      ],
+                      sourceMap: !dev,
+                    },
+                  },
+                ].filter(Boolean),
+            // A global CSS import always has side effects. Webpack will tree
+            // shake the CSS without this option if the issuer claims to have
+            // no side-effects.
+            // See https://github.com/webpack/webpack/issues/6571
+            sideEffects: true,
+          } as webpack.RuleSetRule),
+        config.experimental.css &&
+          ({
+            loader: require.resolve('file-loader'),
+            issuer: {
+              // file-loader is only used for CSS files, e.g. url() for a SVG
+              // or font files
+              test: /\.css$/,
+            },
+            // Exclude extensions that webpack handles by default
+            exclude: [/\.(js|mjs|jsx|ts|tsx)$/, /\.html$/, /\.json$/],
+            options: {
+              name: 'static/media/[name].[hash].[ext]',
+            },
+          } as webpack.RuleSetRule),
       ].filter(Boolean),
     },
     plugins: [
@@ -652,6 +748,14 @@ export default async function getBaseWebpackConfig(
           clientManifest: config.experimental.granularChunks,
           modern: config.experimental.modern,
         }),
+      // Extract CSS as CSS file(s) in the client-side production bundle.
+      config.experimental.css &&
+        !isServer &&
+        !dev &&
+        new MiniCssExtractPlugin({
+          filename: 'static/css/[contenthash].css',
+          chunkFilename: 'static/css/[contenthash].chunk.css',
+        }),
       tracer &&
         new ProfilingPlugin({
           tracer,

packages/next/client/index.js

@@ -238,10 +238,28 @@ function renderReactElement (reactEl, domEl) {
 
   // The check for `.hydrate` is there to support React alternatives like preact
   if (isInitialRender) {
-    ReactDOM.hydrate(reactEl, domEl, markHydrateComplete)
+    ReactDOM.hydrate(reactEl, domEl, function () {
+      if (process.env.NODE_ENV !== 'production') {
+        document
+          .querySelectorAll('[data-next-hydrating]')
+          .forEach(function (el) {
+            el.remove()
+          })
+      }
+      markHydrateComplete()
+    })
     isInitialRender = false
   } else {
-    ReactDOM.render(reactEl, domEl, markRenderComplete)
+    ReactDOM.render(reactEl, domEl, function () {
+      if (process.env.NODE_ENV !== 'production') {
+        document
+          .querySelectorAll('[data-next-hydrating]')
+          .forEach(function (el) {
+            el.remove()
+          })
+      }
+      markRenderComplete()
+    })
   }
 }
 

packages/next/next-server/lib/utils.ts

@@ -140,6 +140,8 @@ export type DocumentProps = DocumentInitialProps & {
   inAmpMode: boolean
   hybridAmp: boolean
   staticMarkup: boolean
+  isDevelopment: boolean
+  hasCssMode: boolean
   devFiles: string[]
   files: string[]
   dynamicImports: ManifestItem[]

packages/next/next-server/server/config.ts

@@ -40,6 +40,7 @@ const defaultConfig: { [key: string]: any } = {
       (Number(process.env.CIRCLE_NODE_TOTAL) ||
         (os.cpus() || { length: 1 }).length) - 1
     ),
+    css: false,
     documentMiddleware: false,
     granularChunks: false,
     modern: false,

packages/next/next-server/server/next-server.ts

@@ -76,6 +76,7 @@ export default class Server {
     assetPrefix?: string
     canonicalBase: string
     documentMiddlewareEnabled: boolean
+    hasCssMode: boolean
     dev?: boolean
   }
   private compression?: Middleware
@@ -121,6 +122,7 @@ export default class Server {
       canonicalBase: this.nextConfig.amp.canonicalBase,
       documentMiddlewareEnabled: this.nextConfig.experimental
         .documentMiddleware,
+      hasCssMode: this.nextConfig.experimental.css,
       staticMarkup,
       buildId: this.buildId,
       generateEtags,

packages/next/next-server/server/render.tsx

@@ -130,6 +130,7 @@ type RenderOpts = {
   runtimeConfig?: { [key: string]: any }
   dangerousAsPath: string
   assetPrefix?: string
+  hasCssMode: boolean
   err?: Error | null
   autoExport?: boolean
   nextExport?: boolean
@@ -168,6 +169,7 @@ function renderDocument(
     skeleton,
     dynamicImportsIds,
     dangerousAsPath,
+    hasCssMode,
     err,
     dev,
     ampPath,
@@ -219,6 +221,8 @@ function renderDocument(
           canonicalBase={canonicalBase}
           ampPath={ampPath}
           inAmpMode={inAmpMode}
+          isDevelopment={!!dev}
+          hasCssMode={hasCssMode}
           hybridAmp={hybridAmp}
           staticMarkup={staticMarkup}
           devFiles={devFiles}

packages/next/package.json

@@ -84,20 +84,28 @@
     "conf": "5.0.0",
     "content-type": "1.0.4",
     "cookie": "0.4.0",
+    "css-loader": "3.2.0",
     "devalue": "2.0.0",
     "etag": "1.8.1",
+    "file-loader": "4.2.0",
     "find-up": "4.0.0",
     "fork-ts-checker-webpack-plugin": "1.3.4",
     "fresh": "0.5.2",
+    "ignore-loader": "0.1.2",
     "is-docker": "2.0.0",
     "jest-worker": "24.9.0",
     "launch-editor": "2.2.1",
     "loader-utils": "1.2.3",
+    "mini-css-extract-plugin": "0.8.0",
     "mkdirp": "0.5.1",
     "node-fetch": "2.6.0",
+    "optimize-css-assets-webpack-plugin": "5.0.3",
     "ora": "3.4.0",
     "path-to-regexp": "2.1.0",
     "pnp-webpack-plugin": "1.5.0",
+    "postcss-flexbugs-fixes": "4.1.0",
+    "postcss-loader": "3.0.0",
+    "postcss-preset-env": "6.7.0",
     "prop-types": "15.7.2",
     "prop-types-exact": "1.2.0",
     "raw-body": "2.4.0",
@@ -107,6 +115,7 @@
     "source-map": "0.6.1",
     "string-hash": "1.1.3",
     "strip-ansi": "5.2.0",
+    "style-loader": "1.0.0",
     "styled-jsx": "3.2.2",
     "terser": "4.0.0",
     "unfetch": "4.1.0",
@@ -141,9 +150,11 @@
     "@types/find-up": "2.1.1",
     "@types/fresh": "0.5.0",
     "@types/loader-utils": "1.1.3",
+    "@types/mini-css-extract-plugin": "0.8.0",
     "@types/mkdirp": "0.5.2",
     "@types/nanoid": "2.0.0",
     "@types/node-fetch": "2.3.4",
+    "@types/optimize-css-assets-webpack-plugin": "5.0.0",
     "@types/react": "16.8.18",
     "@types/react-dom": "16.8.4",
     "@types/react-is": "16.7.1",

packages/next/pages/_document.tsx

@@ -344,6 +344,25 @@ export class Head extends Component<
 
     return (
       <head {...this.props}>
+        {this.context._documentProps.isDevelopment &&
+          this.context._documentProps.hasCssMode && (
+            <>
+              <style
+                data-next-hydrating
+                dangerouslySetInnerHTML={{
+                  __html: `body{-webkit-animation:-next-hydrating 3s steps(1,end) 0s 1 normal both;-moz-animation:-next-hydrating 3s steps(1,end) 0s 1 normal both;-ms-animation:-next-hydrating 3s steps(1,end) 0s 1 normal both;animation:-next-hydrating 3s steps(1,end) 0s 1 normal both}@-webkit-keyframes -next-hydrating{from{visibility:hidden}to{visibility:visible}}@-moz-keyframes -next-hydrating{from{visibility:hidden}to{visibility:visible}}@-ms-keyframes -next-hydrating{from{visibility:hidden}to{visibility:visible}}@-o-keyframes -next-hydrating{from{visibility:hidden}to{visibility:visible}}@keyframes -next-hydrating{from{visibility:hidden}to{visibility:visible}}`,
+                }}
+              />
+              <noscript>
+                <style
+                  data-next-hydrating
+                  dangerouslySetInnerHTML={{
+                    __html: `body{-webkit-animation:none;-moz-animation:none;-ms-animation:none;animation:none}`,
+                  }}
+                />
+              </noscript>
+            </>
+          )}
         {children}
         {head}
         <meta

test/integration/css/fixtures/compilation-and-prefixing/pages/_app.js

@@ -0,0 +1,12 @@
+import React from 'react'
+import App from 'next/app'
+import '../styles/global.css'
+
+class MyApp extends App {
+  render () {
+    const { Component, pageProps } = this.props
+    return <Component {...pageProps} />
+  }
+}
+
+export default MyApp

test/integration/css/fixtures/compilation-and-prefixing/pages/index.js

@@ -0,0 +1,3 @@
+export default function Home () {
+  return <div className='red-text'>This text should be red.</div>
+}

test/integration/css/fixtures/compilation-and-prefixing/styles/global.css

@@ -0,0 +1,5 @@
+@media (480px <= width < 768px) {
+  ::placeholder {
+    color: green;
+  }
+}

test/integration/css/fixtures/invalid-global-with-app/pages/_app.js

@@ -0,0 +1,11 @@
+import React from 'react'
+import App from 'next/app'
+
+class MyApp extends App {
+  render () {
+    const { Component, pageProps } = this.props
+    return <Component {...pageProps} />
+  }
+}
+
+export default MyApp

test/integration/css/fixtures/invalid-global-with-app/pages/index.js

@@ -0,0 +1,5 @@
+import '../styles/global.css'
+
+export default function Home () {
+  return <div className='red-text'>This text should be red.</div>
+}

test/integration/css/fixtures/invalid-global-with-app/styles/global.css

@@ -0,0 +1,3 @@
+.red-text {
+  color: red;
+}

test/integration/css/fixtures/invalid-global/pages/index.js

@@ -0,0 +1,5 @@
+import '../styles/global.css'
+
+export default function Home () {
+  return <div className='red-text'>This text should be red.</div>
+}

test/integration/css/fixtures/invalid-global/styles/global.css

@@ -0,0 +1,3 @@
+.red-text {
+  color: red;
+}

test/integration/css/fixtures/multi-global-reversed/pages/_app.js

@@ -0,0 +1,13 @@
+import React from 'react'
+import App from 'next/app'
+import '../styles/global2.css'
+import '../styles/global1.css'
+
+class MyApp extends App {
+  render () {
+    const { Component, pageProps } = this.props
+    return <Component {...pageProps} />
+  }
+}
+
+export default MyApp

test/integration/css/fixtures/multi-global-reversed/pages/index.js

@@ -0,0 +1,3 @@
+export default function Home () {
+  return <div className='red-text'>This text should be red.</div>
+}

test/integration/css/fixtures/multi-global-reversed/styles/global1.css

@@ -0,0 +1,3 @@
+.red-text {
+  color: red;
+}

test/integration/css/fixtures/multi-global-reversed/styles/global2.css

@@ -0,0 +1,3 @@
+.blue-text {
+  color: blue;
+}