Script Modules: Add new API to embed server data in HTML.

Add a new filter `script_module_data_{$module_id}` to associate data
with a Script Module. For example:

{{{#!php
add_filter(
	'script_module_data_MyScriptModuleID',
	function ( array $data ): array {
		$data['script-needs-this-data'] = 'ok';
		return $data;
	}
);
}}}

If the Script Module is included in the page, enqueued or as a
dependency, the associated data will be JSON-encoded and embedded in the
HTML in a `<script type="application/json">` tag with an ID of the form
`wp-script-module-data-{$module_id}` allowing the Script Module to
access the data on the client.

See the original proposal: https://make.wordpress.org/core/2024/05/06/proposal-server-to-client-data-sharing-for-script-modules/

Developed in https://github.com/WordPress/wordpress-develop/pull/6682.

Props jonsurrell, cbravobernal, westonruter, gziolo, bernhard-reiter, youknowriad, sergiomdgomes, czapla.
Fixes #61510. See #60647.
Built from https://develop.svn.wordpress.org/trunk@58579


git-svn-id: http://core.svn.wordpress.org/trunk@58026 1a063a9b-81f0-0310-95a4-ce76da25c4cd

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

@@ -182,6 +182,9 @@ class WP_Script_Modules {
 		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_module_data' ) );
+		add_action( 'admin_print_footer_scripts', array( $this, 'print_script_module_data' ) );
 	}
 
 	/**
@@ -363,4 +366,119 @@ class WP_Script_Modules {
 
 		return $src;
 	}
+
+	/**
+	 * Print data associated with Script Modules.
+	 *
+	 * The data will be embedded in the page HTML and can be read by Script Modules on page load.
+	 *
+	 * @since 6.7.0
+	 *
+	 * Data can be associated with a Script Module via the
+	 * {@see "script_module_data_{$module_id}"} filter.
+	 *
+	 * The data for a Script Module will be serialized as JSON in a script tag with an ID of the
+	 * form `wp-script-module-data-{$module_id}`.
+	 */
+	public function print_script_module_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 $module_id ) {
+			/**
+			 * Filters data associated with a given Script Module.
+			 *
+			 * Script Modules may require data that is required for initialization or is essential
+			 * to have immediately available on page load. These are suitable use cases for
+			 * this data.
+			 *
+			 * The dynamic portion of the hook name, `$module_id`, refers to the Script Module ID
+			 * that the data is associated with.
+			 *
+			 * This is best suited to pass essential data that must be available to the module for
+			 * initialization or immediately on page load. It does not replace the REST API or
+			 * fetching data from the client.
+			 *
+			 * @example
+			 *   add_filter(
+			 *     'script_module_data_MyScriptModuleID',
+			 *     function ( array $data ): array {
+			 *       $data['script-needs-this-data'] = 'ok';
+			 *       return $data;
+			 *     }
+			 *   );
+			 *
+			 * If the filter returns no data (an empty array), nothing will be embedded in the page.
+			 *
+			 * The data for a given Script Module, if provided, will be JSON serialized in a script
+			 * tag with an ID of the form `wp-script-module-data-{$module_id}`.
+			 *
+			 * The data can be read on the client with a pattern like this:
+			 *
+			 * @example
+			 *   const dataContainer = document.getElementById( 'wp-script-module-data-MyScriptModuleID' );
+			 *   let data = {};
+			 *   if ( dataContainer ) {
+			 *     try {
+			 *       data = JSON.parse( dataContainer.textContent );
+			 *     } catch {}
+			 *   }
+			 *   initMyScriptModuleWithData( data );
+			 *
+			 * @since 6.7.0
+			 *
+			 * @param array $data The data associated with the Script Module.
+			 */
+			$data = apply_filters( "script_module_data_{$module_id}", array() );
+
+			if ( is_array( $data ) && array() !== $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 /.
+				 *
+				 * If the page will use UTF-8 encoding, it's safe to print unescaped unicode:
+				 *
+				 *   - JSON_UNESCAPED_UNICODE: Encode multibyte Unicode characters literally (instead of 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 requires encoding in UTF-8, so if the generated HTML page
+				 * is not encoded in UTF-8 then it's not safe to include those literals. They must
+				 * be escaped to avoid encoding issues.
+				 *
+				 * @see https://www.rfc-editor.org/rfc/rfc8259.html for details on encoding requirements.
+				 * @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 | JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_LINE_TERMINATORS;
+				if ( ! is_utf8_charset() ) {
+					$json_encode_flags = JSON_HEX_TAG | JSON_UNESCAPED_SLASHES;
+				}
+
+				wp_print_inline_script_tag(
+					wp_json_encode(
+						$data,
+						$json_encode_flags
+					),
+					array(
+						'type' => 'application/json',
+						'id'   => "wp-script-module-data-{$module_id}",
+					)
+				);
+			}
+		}
+	}
 }

wp-includes/version.php

@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.7-alpha-58578';
+$wp_version = '6.7-alpha-58579';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.