feat(v2): minor webpack build perf optimization (#1612)

* feat(v2): improve webpack build time

* revert devtool

* nits

* nits

* prettier

packages/docusaurus-plugin-content-blog/src/index.js

@@ -359,7 +359,7 @@ module.exports = function(context, opts) {
                 {
                   loader: path.resolve(__dirname, './markdownLoader.js'),
                 },
-              ],
+              ].filter(Boolean),
             },
           ],
         },

packages/docusaurus-plugin-content-docs-legacy/src/index.js

@@ -181,7 +181,7 @@ module.exports = function(context, opts) {
                     sourceToPermalink: globalContents.sourceToPermalink,
                   },
                 },
-              ],
+              ].filter(Boolean),
             },
           ],
         },

packages/docusaurus/package.json

@@ -68,6 +68,7 @@
     "semver": "^6.1.1",
     "shelljs": "^0.8.3",
     "static-site-generator-webpack-plugin": "^3.4.2",
+    "std-env": "^2.2.1",
     "style-loader": "^0.23.1",
     "terser-webpack-plugin": "^1.3.0",
     "wait-file": "^1.0.1",

packages/docusaurus/src/webpack/base.ts

@@ -10,7 +10,7 @@ import MiniCssExtractPlugin from 'mini-css-extract-plugin';
 import OptimizeCSSAssetsPlugin from 'optimize-css-assets-webpack-plugin';
 import path from 'path';
 import TerserPlugin from 'terser-webpack-plugin';
-import {Configuration} from 'webpack';
+import {Configuration, Loader} from 'webpack';
 
 import {Props} from '../server/types';
 import {getBabelLoader, getCacheLoader, getStyleLoaders} from './utils';
@@ -34,6 +34,7 @@ export function createBaseConfig(
   return {
     mode: isProd ? 'production' : 'development',
     output: {
+      pathinfo: false,
       path: outDir,
       filename: isProd ? '[name].[chunkhash].js' : '[name].js',
       chunkFilename: isProd ? '[name].[chunkhash].js' : '[name].js',
@@ -43,7 +44,7 @@ export function createBaseConfig(
     performance: {
       hints: false,
     },
-    devtool: !isProd && 'cheap-module-eval-source-map',
+    devtool: isProd ? false : 'cheap-module-eval-source-map',
     resolve: {
       symlinks: true,
       alias: {
@@ -132,7 +133,7 @@ export function createBaseConfig(
           use: [
             cacheLoader && getCacheLoader(isServer),
             getBabelLoader(isServer),
-          ].filter(Boolean),
+          ].filter(Boolean) as Loader[],
         },
         {
           test: CSS_REGEX,

packages/docusaurus/src/webpack/utils.ts

@@ -6,6 +6,7 @@
  */
 
 import MiniCssExtractPlugin from 'mini-css-extract-plugin';
+import env from 'std-env';
 import merge from 'webpack-merge';
 import {Configuration, Loader} from 'webpack';
 
@@ -43,7 +44,14 @@ export function getStyleLoaders(
   return loaders;
 }
 
-export function getCacheLoader(isServer: boolean, cacheOptions?: {}): Loader {
+export function getCacheLoader(
+  isServer: boolean,
+  cacheOptions?: {},
+): Loader | null {
+  if (env.ci || env.test) {
+    return null;
+  }
+
   return {
     loader: require.resolve('cache-loader'),
     options: Object.assign(

yarn.lock

@@ -3712,7 +3712,7 @@ chrome-trace-event@^1.0.0:
   dependencies:
     tslib "^1.9.0"
 
-ci-info@^1.5.0:
+ci-info@^1.5.0, ci-info@^1.6.0:
   version "1.6.0"
   resolved "https://registry.yarnpkg.com/ci-info/-/ci-info-1.6.0.tgz#2ca20dbb9ceb32d4524a683303313f0304b1e497"
   integrity sha512-vsGdkwSCDpWmP80ncATX7iea5DWQemg1UgCW5J8tqjU3lYw4FBYuj89J0CTVomA7BEfvSZd84GmHko+MxFQU2A==
@@ -13097,6 +13097,13 @@ std-env@^1.1.0, std-env@^1.3.1:
   dependencies:
     is-ci "^1.1.0"
 
+std-env@^2.2.1:
+  version "2.2.1"
+  resolved "https://registry.yarnpkg.com/std-env/-/std-env-2.2.1.tgz#2ffa0fdc9e2263e0004c1211966e960948a40f6b"
+  integrity sha512-IjYQUinA3lg5re/YMlwlfhqNRTzMZMqE+pezevdcTaHceqx8ngEi1alX9nNCk9Sc81fy1fLDeQoaCzeiW1yBOQ==
+  dependencies:
+    ci-info "^1.6.0"
+
 stealthy-require@^1.1.1:
   version "1.1.1"
   resolved "https://registry.yarnpkg.com/stealthy-require/-/stealthy-require-1.1.1.tgz#35b09875b4ff49f26a777e509b3090a3226bf24b"