Create a separate bundle for cart and checkout (#48010)

plugins/woocommerce-blocks/bin/add-split-chunk-dependencies.js

@@ -0,0 +1,75 @@
+// The Dependency Extraction Webpack Plugin does not add split chunks as dependencies
+// to the .asset.php files that list dependencies. In the past we manually enqueued
+// those dependencies in PHP.
+// For every generated .asset.php file in the whole bundle, this plugin prefixes the
+// list of dependencies with the handles of split chunks that were generated in the build.
+
+// e.g. if your bundle has a vendors script called foo-vendors then for every entry-point
+// that has a .asset.php file generated by Dependency Extraction Webpack Plugin
+// the plugin will edit that file to include foo-vendors as a listed dependency.
+
+// This means for any split chunk you build you'll only need to register it in PHP, but all
+// files that depend on it will automatically include it as a dependency.
+class AddSplitChunkDependencies {
+	apply( compiler ) {
+		compiler.hooks.thisCompilation.tap(
+			'AddStableChunksToAssets',
+			( compilation, callback ) => {
+				compilation.hooks.processAssets.tap(
+					{
+						name: 'AddStableChunksToAssets',
+						stage: compiler.webpack.Compilation
+							.PROCESS_ASSETS_STAGE_ANALYSE,
+					},
+					() => {
+						const { chunks } = compilation;
+
+						const splitChunks = chunks.filter( ( chunk ) => {
+							return chunk?.chunkReason?.includes( 'split' );
+						} );
+
+						// find files that have an asset.php file
+						const chunksToAddSplitsTo = chunks.filter(
+							( chunk ) => {
+								return (
+									! chunk?.chunkReason?.includes( 'split' ) &&
+									chunk.files.find( ( file ) =>
+										file.endsWith( 'asset.php' )
+									)
+								);
+							}
+						);
+
+						for ( const chunk of chunksToAddSplitsTo ) {
+							const assetFile = chunk.files.find( ( file ) =>
+								file.endsWith( 'asset.php' )
+							);
+
+							const assetFileContent = compilation.assets[
+								assetFile
+							]
+								.source()
+								.toString();
+
+							const extraDependencies = splitChunks
+								.map( ( c ) => `'${ c.name }'` )
+								.join( ', ' );
+
+							const updatedFileContent = assetFileContent.replace(
+								/('dependencies'\s*=>\s*array\s*\(\s*)([^)]*)\)/,
+								`$1${ extraDependencies }, $2)`
+							);
+
+							compilation.assets[ assetFile ] = {
+								source: () => updatedFileContent,
+								size: () => updatedFileContent.length,
+							};
+						}
+					}
+				);
+			}
+		);
+	}
+}
+
+module.exports = AddSplitChunkDependencies;

plugins/woocommerce-blocks/bin/webpack-configs.js

@@ -28,6 +28,7 @@ const {
 	getProgressBarPluginConfig,
 	getCacheGroups,
 } = require( './webpack-helpers' );
+const AddSplitChunkDependencies = require( './add-split-chunk-dependencies' );
 
 const isProduction = NODE_ENV === 'production';
 
@@ -330,17 +331,6 @@ const getFrontConfig = ( options = {} ) => {
 			// @see https://github.com/Automattic/jetpack/pull/20926
 			chunkFilename: `[name]-frontend${ fileSuffix }.js?ver=[contenthash]`,
 			filename: ( pathData ) => {
-				// blocksCheckout and blocksComponents were moved from core bundle,
-				// retain their filenames to avoid breaking translations.
-				if (
-					pathData.chunk.name === 'blocksCheckout' ||
-					pathData.chunk.name === 'blocksComponents'
-				) {
-					return `${ paramCase(
-						pathData.chunk.name
-					) }${ fileSuffix }.js`;
-				}
-
 				return `[name]-frontend${ fileSuffix }.js`;
 			},
 			uniqueName: 'webpackWcBlocksFrontendJsonp',
@@ -395,9 +385,10 @@ const getFrontConfig = ( options = {} ) => {
 				minSize: 200000,
 				automaticNameDelimiter: '--',
 				cacheGroups: {
-					commons: {
+					vendor: {
 						test: /[\\/]node_modules[\\/]/,
-						name: 'wc-blocks-vendors',
+						// Note that filenames are suffixed with `frontend` so the generated file is `wc-blocks-frontend-vendors-frontend`.
+						name: 'wc-blocks-frontend-vendors',
 						chunks: ( chunk ) => {
 							return (
 								chunk.name !== 'product-button-interactivity'
@@ -431,6 +422,7 @@ const getFrontConfig = ( options = {} ) => {
 				bundleAnalyzerReportTitle: 'Frontend',
 			} ),
 			new ProgressBarPlugin( getProgressBarPluginConfig( 'Frontend' ) ),
+			new AddSplitChunkDependencies(),
 		],
 		resolve: {
 			...resolve,
@@ -986,6 +978,151 @@ const getInteractivityAPIConfig = ( options = {} ) => {
 	};
 };
 
+const getCartAndCheckoutFrontendConfig = ( options = {} ) => {
+	let { fileSuffix } = options;
+	const { alias, resolvePlugins = [] } = options;
+	fileSuffix = fileSuffix ? `-${ fileSuffix }` : '';
+
+	const resolve = alias
+		? {
+				alias,
+				plugins: resolvePlugins,
+		  }
+		: {
+				plugins: resolvePlugins,
+		  };
+	return {
+		entry: getEntryConfig(
+			'cartAndCheckoutFrontend',
+			options.exclude || []
+		),
+		output: {
+			devtoolNamespace: 'wc',
+			path: path.resolve( __dirname, '../build/' ),
+			// This is a cache busting mechanism which ensures that the script is loaded via the browser with a ?ver=hash
+			// string. The hash is based on the built file contents.
+			// @see https://github.com/webpack/webpack/issues/2329
+			// Using the ?ver string is needed here so the filename does not change between builds. The WordPress
+			// i18n system relies on the hash of the filename, so changing that frequently would result in broken
+			// translations which we must avoid.
+			// @see https://github.com/Automattic/jetpack/pull/20926
+			chunkFilename: `[name]-frontend${ fileSuffix }.js?ver=[contenthash]`,
+			filename: ( pathData ) => {
+				// blocksCheckout and blocksComponents were moved from core bundle,
+				// retain their filenames to avoid breaking translations.
+				if (
+					pathData.chunk.name === 'blocksCheckout' ||
+					pathData.chunk.name === 'blocksComponents'
+				) {
+					return `${ paramCase(
+						pathData.chunk.name
+					) }${ fileSuffix }.js`;
+				}
+
+				return `[name]-frontend${ fileSuffix }.js`;
+			},
+			uniqueName: 'webpackWcBlocksCartCheckoutFrontendJsonp',
+			library: [ 'wc', '[name]' ],
+		},
+		module: {
+			rules: [
+				{
+					test: /\.(j|t)sx?$/,
+					exclude: /node_modules/,
+					use: {
+						loader: 'babel-loader',
+						options: {
+							presets: [
+								[
+									'@wordpress/babel-preset-default',
+									{
+										modules: false,
+										targets: {
+											browsers: [
+												'extends @wordpress/browserslist-config',
+											],
+										},
+									},
+								],
+							],
+							plugins: [
+								isProduction
+									? require.resolve(
+											'babel-plugin-transform-react-remove-prop-types'
+									  )
+									: false,
+								'@babel/plugin-proposal-optional-chaining',
+								'@babel/plugin-proposal-class-properties',
+							].filter( Boolean ),
+							cacheDirectory: true,
+						},
+					},
+				},
+				{
+					test: /\.s[c|a]ss$/,
+					use: {
+						loader: 'ignore-loader',
+					},
+				},
+			],
+		},
+		optimization: {
+			concatenateModules:
+				isProduction && ! process.env.WP_BUNDLE_ANALYZER,
+			splitChunks: {
+				minSize: 200000,
+				automaticNameDelimiter: '--',
+				cacheGroups: {
+					commons: {
+						test: /[\\/]node_modules[\\/]/,
+						name: 'wc-cart-checkout-vendors',
+						chunks: 'all',
+						enforce: true,
+					},
+					base: {
+						// A refined include blocks and settings that are shared between cart and checkout that produces the smallest possible bundle.
+						test: /assets[\\/]js[\\/](settings|previews|base|data|utils|blocks[\\/]cart-checkout-shared|icons)|packages[\\/](checkout|components)|atomic[\\/]utils/,
+						name: 'wc-cart-checkout-base',
+						chunks: 'all',
+						enforce: true,
+					},
+					...getCacheGroups(),
+				},
+			},
+			minimizer: [
+				new TerserPlugin( {
+					parallel: true,
+					terserOptions: {
+						output: {
+							comments: /translators:/i,
+						},
+						compress: {
+							passes: 2,
+						},
+						mangle: {
+							reserved: [ '__', '_n', '_nx', '_x' ],
+						},
+					},
+					extractComments: false,
+				} ),
+			],
+		},
+		plugins: [
+			...getSharedPlugins( {
+				bundleAnalyzerReportTitle: 'Cart & Checkout Frontend',
+			} ),
+			new ProgressBarPlugin(
+				getProgressBarPluginConfig( 'Cart & Checkout Frontend' )
+			),
+			new AddSplitChunkDependencies(),
+		],
+		resolve: {
+			...resolve,
+			extensions: [ '.js', '.ts', '.tsx' ],
+		},
+	};
+};
+
 module.exports = {
 	getCoreConfig,
 	getFrontConfig,
@@ -995,4 +1132,5 @@ module.exports = {
 	getSiteEditorConfig,
 	getStylingConfig,
 	getInteractivityAPIConfig,
+	getCartAndCheckoutFrontendConfig,
 };

plugins/woocommerce-blocks/bin/webpack-entries.js

@@ -25,9 +25,7 @@ const blocks = {
 	},
 	'attribute-filter': {},
 	breadcrumbs: {},
-	cart: {},
 	'catalog-sorting': {},
-	checkout: {},
 	'coming-soon': {},
 	'customer-account': {},
 	'featured-category': {
@@ -43,10 +41,6 @@ const blocks = {
 		customDir: 'classic-template',
 	},
 	'classic-shortcode': {},
-	'mini-cart': {},
-	'mini-cart-contents': {
-		customDir: 'mini-cart/mini-cart-contents',
-	},
 	'store-notices': {},
 	'page-content-wrapper': {},
 	'price-filter': {},
@@ -169,12 +163,22 @@ const blocks = {
 	},
 };
 
+// Intentional separation of cart and checkout entry points to allow for better code splitting.
+const cartAndCheckoutBlocks = {
+	cart: {},
+	checkout: {},
+	'mini-cart': {},
+	'mini-cart-contents': {
+		customDir: 'mini-cart/mini-cart-contents',
+	},
+};
+
 // Returns the entries for each block given a relative path (ie: `index.js`,
 // `**/*.scss`...).
 // It also filters out elements with undefined props and experimental blocks.
-const getBlockEntries = ( relativePath ) => {
+const getBlockEntries = ( relativePath, blockEntries = blocks ) => {
 	return Object.fromEntries(
-		Object.entries( blocks )
+		Object.entries( blockEntries )
 			.map( ( [ blockCode, config ] ) => {
 				const filePaths = glob.sync(
 					`./assets/js/blocks/${ config.customDir || blockCode }/` +
@@ -206,7 +210,10 @@ const entries = {
 			'./assets/js/atomic/blocks/product-elements/product-details/index.tsx',
 		'add-to-cart-form':
 			'./assets/js/atomic/blocks/product-elements/add-to-cart-form/index.tsx',
-		...getBlockEntries( '{index,block,frontend}.{t,j}s{,x}' ),
+		...getBlockEntries( '{index,block,frontend}.{t,j}s{,x}', {
+			...blocks,
+			...cartAndCheckoutBlocks,
+		} ),
 
 		// Interactivity component styling
 		'wc-interactivity-checkbox-list':
@@ -239,17 +246,14 @@ const entries = {
 		'wc-blocks': './assets/js/index.js',
 
 		// Blocks
-		...getBlockEntries( 'index.{t,j}s{,x}' ),
+		...getBlockEntries( 'index.{t,j}s{,x}', {
+			...blocks,
+			...cartAndCheckoutBlocks,
+		} ),
 	},
 	frontend: {
 		reviews: './assets/js/blocks/reviews/frontend.ts',
 		...getBlockEntries( 'frontend.{t,j}s{,x}' ),
-
-		blocksCheckout: './packages/checkout/index.js',
-		blocksComponents: './packages/components/index.ts',
-
-		'mini-cart-component':
-			'./assets/js/blocks/mini-cart/component-frontend.tsx',
 		'product-button-interactivity':
 			'./assets/js/atomic/blocks/product-elements/button/frontend.tsx',
 	},
@@ -273,6 +277,13 @@ const entries = {
 		'wc-blocks-classic-template-revert-button':
 			'./assets/js/templates/revert-button/index.tsx',
 	},
+	cartAndCheckoutFrontend: {
+		...getBlockEntries( 'frontend.{t,j}s{,x}', cartAndCheckoutBlocks ),
+		blocksCheckout: './packages/checkout/index.js',
+		blocksComponents: './packages/components/index.ts',
+		'mini-cart-component':
+			'./assets/js/blocks/mini-cart/component-frontend.tsx',
+	},
 };
 
 const getEntryConfig = ( type = 'main', exclude = [] ) => {

plugins/woocommerce-blocks/webpack.config.js

@@ -11,6 +11,7 @@ const {
 	getSiteEditorConfig,
 	getStylingConfig,
 	getInteractivityAPIConfig,
+	getCartAndCheckoutFrontendConfig,
 } = require( './bin/webpack-configs.js' );
 
 // Only options shared between all configs should be defined here.
@@ -34,6 +35,11 @@ const sharedConfig = {
 	devtool: NODE_ENV === 'development' ? 'source-map' : false,
 };
 
+const CartAndCheckoutFrontendConfig = {
+	...sharedConfig,
+	...getCartAndCheckoutFrontendConfig( { alias: getAlias() } ),
+};
+
 // Core config for shared libraries.
 const CoreConfig = {
 	...sharedConfig,
@@ -95,6 +101,7 @@ const SiteEditorConfig = {
 };
 
 module.exports = [
+	CartAndCheckoutFrontendConfig,
 	CoreConfig,
 	MainConfig,
 	FrontendConfig,

plugins/woocommerce/changelog/48010-dev-cart-checkout-bundle

@@ -0,0 +1,4 @@
+Significance: minor
+Type: dev
+
+Create a separate JS cart and checkout JavaScript bundle to improve performance.

plugins/woocommerce/src/Blocks/AssetsController.php

@@ -40,6 +40,7 @@ final class AssetsController {
 		add_action( 'admin_enqueue_scripts', array( $this, 'update_block_style_dependencies' ), 20 );
 		add_action( 'wp_enqueue_scripts', array( $this, 'update_block_settings_dependencies' ), 100 );
 		add_action( 'admin_enqueue_scripts', array( $this, 'update_block_settings_dependencies' ), 100 );
+		add_filter( 'js_do_concat', array( $this, 'skip_boost_minification_for_cart_checkout' ), 10, 2 );
 	}
 
 	/**
@@ -62,9 +63,14 @@ final class AssetsController {
 		// The price package is shared externally so has no blocks prefix.
 		$this->api->register_script( 'wc-price-format', 'assets/client/blocks/price-format.js', array(), false );
 
-		$this->api->register_script( 'wc-blocks-vendors-frontend', $this->api->get_block_asset_build_path( 'wc-blocks-vendors-frontend' ), array(), false );
-		$this->api->register_script( 'wc-blocks-checkout', 'assets/client/blocks/blocks-checkout.js', array( 'wc-blocks-vendors-frontend' ) );
-		$this->api->register_script( 'wc-blocks-components', 'assets/client/blocks/blocks-components.js', array( 'wc-blocks-vendors-frontend' ) );
+		// Vendor scripts for blocks frontends (not including cart and checkout).
+		$this->api->register_script( 'wc-blocks-frontend-vendors', $this->api->get_block_asset_build_path( 'wc-blocks-frontend-vendors-frontend' ), array(), false );
+
+		// Cart and checkout frontend scripts.
+		$this->api->register_script( 'wc-cart-checkout-vendors', $this->api->get_block_asset_build_path( 'wc-cart-checkout-vendors-frontend' ), array(), false );
+		$this->api->register_script( 'wc-cart-checkout-base', $this->api->get_block_asset_build_path( 'wc-cart-checkout-base-frontend' ), array(), false );
+		$this->api->register_script( 'wc-blocks-checkout', 'assets/client/blocks/blocks-checkout.js' );
+		$this->api->register_script( 'wc-blocks-components', 'assets/client/blocks/blocks-components.js' );
 
 		// Register the interactivity components here for now.
 		$this->api->register_script( 'wc-interactivity-dropdown', 'assets/client/blocks/wc-interactivity-dropdown.js', array() );
@@ -253,6 +259,23 @@ final class AssetsController {
 		return $src;
 	}
 
+	/**
+	 * Skip Jetpack Boost minification on older versions of Jetpack Boost where it causes issues.
+	 *
+	 * @param mixed $do_concat Whether to concatenate the script or not.
+	 * @param mixed $handle The script handle.
+	 * @return mixed
+	 */
+	public function skip_boost_minification_for_cart_checkout( $do_concat, $handle ) {
+		$boost_is_outdated = defined( 'JETPACK_BOOST_VERSION' ) && version_compare( JETPACK_BOOST_VERSION, '3.4.2', '<' );
+		$scripts_to_ignore = [
+			'wc-cart-checkout-vendors',
+			'wc-cart-checkout-base',
+		];
+
+		return $boost_is_outdated && in_array( $handle, $scripts_to_ignore, true ) ? false : $do_concat;
+	}
+
 	/**
 	 * Add body classes to the frontend and within admin.
 	 *