perf(v2): significantly reduce bundle size & initial html payload (#1898)

* perf(v2): reduce bundle size significantly with super short chunk name and registry

* changelog

* use hash:8 as id for better long term caching

* even shorter filename. slice contenthash

CHANGELOG-2.x.md

@@ -3,6 +3,7 @@
 ## Unreleased
 
 - Convert sitemap plugin to TypeScript
+- Significantly reduce main bundle size and initial HTML payload on production build. Generated JS files from webpack is also shorter in name.
 
 ## 2.0.0-alpha.31
 

packages/docusaurus-utils/src/__tests__/index.test.ts

@@ -108,6 +108,20 @@ describe('load utils', () => {
     Object.keys(secondAssert).forEach(str => {
       expect(genChunkName(str, undefined, 'blog')).toBe(secondAssert[str]);
     });
+
+    // Only generate short unique id
+    const thirdAssert = {
+      a: '0cc175b9',
+      b: '92eb5ffe',
+      c: '4a8a08f0',
+      d: '8277e091',
+    };
+    Object.keys(thirdAssert).forEach(str => {
+      expect(genChunkName(str, undefined, undefined, true)).toBe(
+        thirdAssert[str],
+      );
+    });
+    expect(genChunkName('d', undefined, undefined, true)).toBe('8277e091');
   });
 
   test('idx', () => {

packages/docusaurus-utils/src/index.ts

@@ -101,19 +101,27 @@ export function genChunkName(
   modulePath: string,
   prefix?: string,
   preferredName?: string,
+  shortId?: boolean,
 ): string {
   let chunkName: string | undefined = chunkNameCache.get(modulePath);
   if (!chunkName) {
-    let str = modulePath;
+    if (shortId) {
-    if (preferredName) {
+      chunkName = createHash('md5')
-      const shortHash = createHash('md5')
         .update(modulePath)
         .digest('hex')
-        .substr(0, 3);
+        .substr(0, 8);
-      str = `${preferredName}${shortHash}`;
+    } else {
+      let str = modulePath;
+      if (preferredName) {
+        const shortHash = createHash('md5')
+          .update(modulePath)
+          .digest('hex')
+          .substr(0, 3);
+        str = `${preferredName}${shortHash}`;
+      }
+      const name = str === '/' ? 'index' : docuHash(str);
+      chunkName = prefix ? `${prefix}---${name}` : name;
     }
-    const name = str === '/' ? 'index' : docuHash(str);
-    chunkName = prefix ? `${prefix}---${name}` : name;
     chunkNameCache.set(modulePath, chunkName);
   }
   return chunkName;

packages/docusaurus/src/client/exports/ComponentCreator.js

@@ -56,9 +56,11 @@ function ComponentCreator(path) {
     }
 
     const chunkRegistry = registry[target] || {};
-    optsLoader[keys.join('.')] = chunkRegistry.loader;
+    /* eslint-disable prefer-destructuring */
-    optsModules.push(chunkRegistry.module);
+    optsLoader[keys.join('.')] = chunkRegistry[0];
-    optsWebpack.push(chunkRegistry.webpack);
+    optsModules.push(chunkRegistry[1]);
+    optsWebpack.push(chunkRegistry[2]);
+    /* eslint-enable prefer-destructuring */
   }
 
   traverseChunk(chunkNames, []);

packages/docusaurus/src/server/index.ts

@@ -117,11 +117,10 @@ export async function load(siteDir: string): Promise<Props> {
     `export default {
 ${Object.keys(registry)
   .map(
-    key => `  '${key}': {
+    key =>
-    'loader': ${registry[key].loader},
+      `  '${key}': [${registry[key].loader}, ${JSON.stringify(
-    'module': ${JSON.stringify(registry[key].modulePath)},
+        registry[key].modulePath,
-    'webpack': require.resolveWeak(${JSON.stringify(registry[key].modulePath)}),
+      )}, require.resolveWeak(${JSON.stringify(registry[key].modulePath)})],`,
-  },`,
   )
   .join('\n')}};\n`,
   );

packages/docusaurus/src/server/routes.ts

@@ -24,6 +24,7 @@ function getModulePath(target: Module): string {
 }
 
 export async function loadRoutes(pluginsRouteConfigs: RouteConfig[]) {
+  const isProd = process.env.NODE_ENV === 'production';
   const routesImports = [
     `import React from 'react';`,
     `import ComponentCreator from '@docusaurus/ComponentCreator';`,
@@ -82,7 +83,7 @@ export async function loadRoutes(pluginsRouteConfigs: RouteConfig[]) {
       }
 
       const modulePath = getModulePath(value as Module);
-      const chunkName = genChunkName(modulePath, prefix, name);
+      const chunkName = genChunkName(modulePath, prefix, name, isProd);
       const loader = `() => import(/* webpackChunkName: '${chunkName}' */ ${JSON.stringify(
         modulePath,
       )})`;

packages/docusaurus/src/webpack/base.ts

@@ -32,8 +32,8 @@ export function createBaseConfig(
     output: {
       pathinfo: false,
       path: outDir,
-      filename: isProd ? '[name].[contenthash].js' : '[name].js',
+      filename: isProd ? '[name].[contenthash:8].js' : '[name].js',
-      chunkFilename: isProd ? '[name].[contenthash].js' : '[name].js',
+      chunkFilename: isProd ? '[name].[contenthash:8].js' : '[name].js',
       publicPath: baseUrl,
     },
     // Don't throw warning when asset created is over 250kb
@@ -157,8 +157,8 @@ export function createBaseConfig(
     },
     plugins: [
       new MiniCssExtractPlugin({
-        filename: isProd ? '[name].[contenthash].css' : '[name].css',
+        filename: isProd ? '[name].[contenthash:8].css' : '[name].css',
-        chunkFilename: isProd ? '[name].[contenthash].css' : '[name].css',
+        chunkFilename: isProd ? '[name].[contenthash:8].css' : '[name].css',
       }),
     ],
   };