feat(v2): minify css (#1572)

* feat(v2): minify css

* fix docusaurus.js logic

packages/docusaurus/package.json

@@ -56,6 +56,7 @@
     "mini-css-extract-plugin": "^0.4.1",
     "nprogress": "^0.2.0",
     "null-loader": "^2.0.0",
+    "optimize-css-assets-webpack-plugin": "^5.0.1",
     "portfinder": "^1.0.13",
     "react-dev-utils": "^9.0.1",
     "react-helmet": "^6.0.0-beta",

packages/docusaurus/src/client/docusaurus.js

@@ -12,23 +12,29 @@ import preloadHelper from './preload';
 import flat from './flat';
 
 const fetched = {};
+const loaded = {};
 
-const canPrefetchOrLoad = routePath => {
+const isSlowConnection = () => {
   // if user is on slow or constrained connection
   if (`connection` in navigator) {
-    if ((navigator.connection.effectiveType || ``).includes(`2g`)) {
-      return false;
-    }
-    if (navigator.connection.saveData) {
-      return false;
+    if (
+      (navigator.connection.effectiveType || ``).includes(`2g`) &&
+      navigator.connection.saveData
+    ) {
+      return true;
     }
   }
-  return !fetched[routePath];
+  return false;
 };
 
+const canPrefetch = routePath =>
+  !isSlowConnection() && !loaded[routePath] && !fetched[routePath];
+
+const canPreload = routePath => !isSlowConnection() && !loaded[routePath];
+
 const docusaurus = {
   prefetch: routePath => {
-    if (!canPrefetchOrLoad(routePath)) {
+    if (!canPrefetch(routePath)) {
       return false;
     }
 
@@ -56,10 +62,10 @@ const docusaurus = {
     return true;
   },
   preload: routePath => {
-    if (!canPrefetchOrLoad(routePath)) {
+    if (!canPreload(routePath)) {
       return false;
     }
-    fetched[routePath] = true;
+    loaded[routePath] = true;
     preloadHelper(routes, routePath);
     return true;
   },

packages/docusaurus/src/webpack/base.ts

@@ -6,6 +6,7 @@
  */
 
 import MiniCssExtractPlugin from 'mini-css-extract-plugin';
+import OptimizeCSSAssetsPlugin from 'optimize-css-assets-webpack-plugin';
 import TerserPlugin from 'terser-webpack-plugin';
 import path from 'path';
 import fs from 'fs-extra';
@@ -73,6 +74,11 @@ export function createBaseConfig(
                 },
               },
             }),
+            new OptimizeCSSAssetsPlugin({
+              cssProcessorPluginOptions: {
+                preset: 'default',
+              },
+            }),
           ]
         : undefined,
       splitChunks: {