Script Modules: Add data server->client data passing

src/wp-includes/block-editor.php

@@ -766,6 +766,13 @@ function block_editor_rest_api_preload( array $preload_paths, $block_editor_cont
 		),
 		'after'
 	);
+	add_filter(
+		'scriptmoduledata_@wordpress/api-fetch',
+		function ( $data ) use ( $preload_data ) {
+			$data['preloadData'] = $preload_data;
+			return $data;
+		}
+	);
 }
 
 /**

src/wp-includes/class-wp-script-modules.php

@@ -178,6 +178,13 @@ public function add_hooks() {
 		add_action( $position, array( $this, 'print_import_map' ) );
 		add_action( $position, array( $this, 'print_enqueued_script_modules' ) );
 		add_action( $position, array( $this, 'print_script_module_preloads' ) );
+
+		add_action( 'admin_print_footer_scripts', array( $this, 'print_import_map' ) );
+		add_action( 'admin_print_footer_scripts', array( $this, 'print_enqueued_script_modules' ) );
+		add_action( 'admin_print_footer_scripts', array( $this, 'print_script_module_preloads' ) );
+
+		add_action( 'wp_footer', array( $this, 'print_script_data' ) );
+		add_action( 'admin_print_footer_scripts', array( $this, 'print_script_data' ) );
 	}
 
 	/**
@@ -359,4 +366,70 @@ private function get_src( string $id ): string {
 
 		return $src;
 	}
+
+	public function print_script_data(): void {
+		$modules = array();
+		foreach ( array_keys( $this->get_marked_for_enqueue() ) as $id ) {
+			$modules[ $id ] = true;
+		}
+		foreach ( array_keys( $this->get_import_map()['imports'] ) as $id ) {
+			$modules[ $id ] = true;
+		}
+
+		foreach ( array_keys( $modules ) as $module_id ) {
+			$data = apply_filters( 'scriptmoduledata_' . $module_id, array() );
+			if ( ! empty( $data ) ) {
+				/*
+				 * This data will be printed as JSON inside a script tag like this:
+				 *   <script type="application/json"></script>
+				 *
+				 * A script tag must be closed by a sequence beginning with `</`. It's impossible to
+				 * close a script tag without using `<`. We ensure that `<` is escaped and `/` can
+				 * remain unescaped, so `</script>` will be printed as `\u003C/script\u00E3`.
+				 *
+				 *   - JSON_HEX_TAG: All < and > are converted to \u003C and \u003E.
+				 *   - JSON_UNESCAPED_SLASHES: Don't escape /.
+				 *
+				 * @see https://www.php.net/manual/en/json.constants.php for details on these constants.
+				 * @see https://html.spec.whatwg.org/#script-data-state for details on script
+				 *      tag parsing.
+				 */
+				$json_encode_flags = JSON_HEX_TAG | JSON_UNESCAPED_SLASHES;
+				if ( 'UTF-8' === get_option( 'blog_charset' ) ) {
+					/*
+					 * If the page will use UTF-8 encoding, it's safe to print unescaped unicode in
+					 * JSON. Set the following flags:
+					 *
+					 * - JSON_UNESCAPED_UNICODE: Encode multibyte Unicode characters literally
+					 *   (default is to escape as \uXXXX).
+					 * - JSON_UNESCAPED_LINE_TERMINATORS: The line terminators are kept unescaped when
+					 *   JSON_UNESCAPED_UNICODE is supplied. It uses the same behaviour as it was
+					 *   before PHP 7.1 without this constant. Available as of PHP 7.1.0.
+					 *
+					 * The JSON specification does not specify a character encoding, RFC-8259
+					 * suggests that UTF-8 be used everywhere. It's risky to print unicode if the page
+					 * uses any other encoding.
+					 *
+					 * > JSON text exchanged between systems that are not part of a closed ecosystem
+					 * > MUST be encoded using UTF-8. Previous specifications of JSON have not required
+					 * > the use of UTF-8 when transmitting JSON text.  However, the vast majority of
+					 * > JSON- based software implementations have chosen to use the UTF-8 encoding,
+					 * > to the extent that it is the only encoding that achieves interoperability.
+					 *
+					 * @see https://www.rfc-editor.org/rfc/rfc8259.html
+					 *
+					 */
+					$json_encode_flags |= JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_LINE_TERMINATORS;
+				}
+
+				wp_print_inline_script_tag(
+					wp_json_encode( $data, $json_encode_flags ),
+					array(
+						'type' => 'application/json',
+						'id'   => 'wp-scriptmodule-data_' . $module_id,
+					)
+				);
+			}
+		}
+	}
 }

src/wp-includes/script-modules.php

@@ -123,3 +123,19 @@ function wp_dequeue_script_module( string $id ) {
 function wp_deregister_script_module( string $id ) {
 	wp_script_modules()->deregister( $id );
 }
+
+
+function wp_register_default_script_modules(): void {
+	add_filter(
+		'scriptmoduledata_@wordpress/api-fetch',
+		function ( $data ) {
+			$data['rootURL']                             = sanitize_url( get_rest_url() );
+			$data['nonce']                               = wp_installing() ? '' : wp_create_nonce( 'wp_rest' );
+			$data['shouldRegisterMediaUploadMiddleware'] = true;
+			$data['nonceEndpoint']                       = admin_url( 'admin-ajax.php?action=rest-nonce' );
+			return $data;
+		}
+	);
+	wp_enqueue_script_module( '__DEV__/noop', includes_url( '/noop.js' ), array( '@wordpress/api-fetch' ) );
+}
+add_action( 'init', 'wp_register_default_script_modules', 0 );

src/wp-includes/theme-previews.php

@@ -53,6 +53,14 @@ function wp_attach_theme_preview_middleware() {
 		),
 		'after'
 	);
+
+	add_filter(
+		'scriptmoduledata_@wordpress/api-fetch',
+		function ( $data ) {
+			$data['themePreviewPath'] = sanitize_text_field( wp_unslash( $_GET['wp_theme_preview'] ) );
+			return $data;
+		}
+	);
 }
 
 /**