Inline the webpack runtime chunk (#5058)

packages/react-dev-utils/InlineChunkHtmlPlugin.js

+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+'use strict';
+
+class InlineChunkHtmlPlugin {
+  constructor(htmlWebpackPlugin, tests) {
+    this.htmlWebpackPlugin = htmlWebpackPlugin;
+    this.tests = tests;
+  }
+
+  getInlinedTag(publicPath, assets, tag) {
+    if (tag.tagName !== 'script' || !(tag.attributes && tag.attributes.src)) {
+      return tag;
+    }
+    const scriptName = tag.attributes.src.replace(publicPath, '');
+    if (!this.tests.some(test => scriptName.match(test))) {
+      return tag;
+    }
+    const asset = assets[scriptName];
+    if (asset == null) {
+      return tag;
+    }
+    return { tagName: 'script', innerHTML: asset.source(), closeTag: true };
+  }
+
+  apply(compiler) {
+    let publicPath = compiler.options.output.publicPath;
+    if (!publicPath.endsWith('/')) {
+      publicPath += '/';
+    }
+
+    compiler.hooks.compilation.tap('InlineChunkHtmlPlugin', compilation => {
+      const tagFunction = tag =>
+        this.getInlinedTag(publicPath, compilation.assets, tag);
+
+      const hooks = this.htmlWebpackPlugin.getHooks(compilation);
+      hooks.alterAssetTagGroups.tap('InlineChunkHtmlPlugin', assets => {
+        assets.headTags = assets.headTags.map(tagFunction);
+        assets.bodyTags = assets.bodyTags.map(tagFunction);
+      });
+      hooks.afterEmit.tap('InlineChunkHtmlPlugin', () => {
+        Object.keys(compilation.assets).forEach(assetName => {
+          if (this.tests.some(test => assetName.match(test))) {
+            delete compilation.assets[assetName];
+          }
+        });
+      });
+    });
+  }
+}
+
+module.exports = InlineChunkHtmlPlugin;

packages/react-dev-utils/README.md

@@ -18,14 +18,14 @@ If you don’t use Create React App, or if you [ejected](https://github.com/face
 
 There is no single entry point. You can only import individual top-level modules.
 
-#### `new InterpolateHtmlPlugin(replacements: {[key:string]: string})`
+#### `new InterpolateHtmlPlugin(htmlWebpackPlugin: HtmlWebpackPlugin, replacements: {[key:string]: string})`
 
 This Webpack plugin lets us interpolate custom variables into `index.html`.<br>
 It works in tandem with [HtmlWebpackPlugin](https://github.com/ampedandwired/html-webpack-plugin) 2.x via its [events](https://github.com/ampedandwired/html-webpack-plugin#events).
 
 ```js
 var path = require('path');
-var HtmlWebpackPlugin = require('html-dev-plugin');
+var HtmlWebpackPlugin = require('html-webpack-plugin');
 var InterpolateHtmlPlugin = require('react-dev-utils/InterpolateHtmlPlugin');
 
 // Webpack config
@@ -56,6 +56,39 @@ module.exports = {
 };
 ```
 
+#### `new InlineChunkHtmlPlugin(htmlWebpackPlugin: HtmlWebpackPlugin, tests: Regex[])`
+
+This Webpack plugin inlines script chunks into `index.html`.<br>
+It works in tandem with [HtmlWebpackPlugin](https://github.com/ampedandwired/html-webpack-plugin) 4.x.
+
+```js
+var path = require('path');
+var HtmlWebpackPlugin = require('html-webpack-plugin');
+var InlineChunkHtmlPlugin = require('react-dev-utils/InlineChunkHtmlPlugin');
+
+// Webpack config
+var publicUrl = '/my-custom-url';
+
+module.exports = {
+  output: {
+    // ...
+    publicPath: publicUrl + '/',
+  },
+  // ...
+  plugins: [
+    // Generates an `index.html` file with the <script> injected.
+    new HtmlWebpackPlugin({
+      inject: true,
+      template: path.resolve('public/index.html'),
+    }),
+    // Inlines chunks with `runtime` in the name
+    new InlineChunkHtmlPlugin(HtmlWebpackPlugin, [/runtime/]),
+    // ...
+  ],
+  // ...
+};
+```
+
 #### `new ModuleScopePlugin(appSrc: string | string[], allowedFiles?: string[])`
 
 This Webpack plugin ensures that relative imports from app's source directories don't reach outside of it.

packages/react-dev-utils/package.json

@@ -24,6 +24,7 @@
     "getCSSModuleLocalIdent.js",
     "getProcessForPort.js",
     "ignoredFiles.js",
+    "InlineChunkHtmlPlugin.js",
     "inquirer.js",
     "InterpolateHtmlPlugin.js",
     "launchEditor.js",

packages/react-scripts/config/webpack.config.prod.js

@@ -12,6 +12,7 @@ const autoprefixer = require('autoprefixer');
 const path = require('path');
 const webpack = require('webpack');
 const HtmlWebpackPlugin = require('html-webpack-plugin');
+const InlineChunkHtmlPlugin = require('react-dev-utils/InlineChunkHtmlPlugin');
 const TerserPlugin = require('terser-webpack-plugin');
 const MiniCssExtractPlugin = require('mini-css-extract-plugin');
 const OptimizeCSSAssetsPlugin = require('optimize-css-assets-webpack-plugin');
@@ -433,6 +434,9 @@ module.exports = {
         minifyURLs: true,
       },
     }),
+    // Inlines the webpack runtime script. This script is too small to warrant
+    // a network request.
+    new InlineChunkHtmlPlugin(HtmlWebpackPlugin, [/runtime~.+[.]js/]),
     // Makes some environment variables available in index.html.
     // The public URL is available as %PUBLIC_URL% in index.html, e.g.:
     // <link rel="shortcut icon" href="%PUBLIC_URL%/favicon.ico">