Changeset 60930 for trunk/src/wp-includes/class-wp-block.php

Timestamp:

10/14/2025 12:10:31 AM (12 months ago)

Author:

westonruter

Message:

Editor: Avoid enqueueing assets for blocks which do not render content.

This change prevents scripts, styles, and script modules from being enqueued for blocks that do not render any HTML content. This is common for hidden blocks or blocks like the Featured Image block when no image is present. This change reduces the amount of unused CSS and JavaScript on a page, improving performance.

A new filter, enqueue_empty_block_content_assets, is introduced to allow developers to override this behavior and enqueue assets for empty blocks if needed.

The implementation involves capturing the asset queues before and after a block is rendered. The newly enqueued assets are only merged if the block's rendered content is not empty. This is done recursively for nested blocks to ensure that assets for inner blocks are also not enqueued if a parent block is hidden.

Developed in ​https://github.com/WordPress/wordpress-develop/pull/9213.

Props westonruter, aristath, peterwilsoncc, gziolo, krupajnanda, dd32, jorbin.
See #50328.
Fixes #63676.

File:

• trunk/src/wp-includes/class-wp-block.php (modified) (2 diffs)

trunk/src/wp-includes/class-wp-block.php

@@ -492 +492 @@
         public function render( $options = array() ) {
                 global $post;
+
+                // Capture the current assets queues and then clear out to capture the diff of what was introduced by rendering.
+                $before_styles_queue         = wp_styles()->queue;
+                $before_scripts_queue        = wp_scripts()->queue;
+                $before_script_modules_queue = wp_script_modules()->queue;
+                wp_styles()->queue           = array();
+                wp_scripts()->queue          = array();
+                wp_script_modules()->queue   = array();
 
                 /*
@@ -662 +670 @@
                 }
 
+                // Capture the new assets enqueued during rendering, and restore the queues the state prior to rendering.
+                $new_styles_queue          = wp_styles()->queue;
+                $new_scripts_queue         = wp_scripts()->queue;
+                $new_script_modules_queue  = wp_script_modules()->queue;
+                wp_styles()->queue         = $before_styles_queue;
+                wp_scripts()->queue        = $before_scripts_queue;
+                wp_script_modules()->queue = $before_script_modules_queue;
+                $has_new_styles            = count( $new_styles_queue ) > 0;
+                $has_new_scripts           = count( $new_scripts_queue ) > 0;
+                $has_new_script_modules    = count( $new_script_modules_queue ) > 0;
+
+                // Merge the newly enqueued assets with the existing assets if the rendered block is not empty.
+                if (
+                        ( $has_new_styles || $has_new_scripts || $has_new_script_modules ) &&
+                        (
+                                trim( $block_content ) !== '' ||
+                                /**
+                                 * Filters whether to enqueue assets for a block which has no rendered content.
+                                 *
+                                 * @since 6.9.0
+                                 *
+                                 * @param bool   $enqueue    Whether to enqueue assets.
+                                 * @param string $block_name Block name.
+                                 */
+                                (bool) apply_filters( 'enqueue_empty_block_content_assets', false, $this->name )
+                        )
+                ) {
+                        if ( $has_new_styles ) {
+                                wp_styles()->queue = array_unique( array_merge( wp_styles()->queue, $new_styles_queue ) );
+                        }
+                        if ( $has_new_scripts ) {
+                                wp_scripts()->queue = array_unique( array_merge( wp_scripts()->queue, $new_scripts_queue ) );
+                        }
+                        if ( $has_new_script_modules ) {
+                                wp_script_modules()->queue = array_unique( array_merge( wp_script_modules()->queue, $new_script_modules_queue ) );
+                        }
+                }
+
                 return $block_content;
         }