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Fix performance regression in the block-level custom CSS feature #11686

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Fix performance regression in the block-level custom CSS feature #11686

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79df64b
Update BASE_TAG default version to 6.8.0
mukeshpanchal27 Apr 16, 2026
57bd3b6
Merge branch 'WordPress:trunk' into trunk
mukeshpanchal27 Apr 30, 2026
98aa939
Return early if no custom CSS class is provided
mukeshpanchal27 Apr 30, 2026
391f5b7
Update default BASE_TAG version to 6.7.0
mukeshpanchal27 Apr 30, 2026
ac2597e
Merge branch 'trunk' into perf/10777
mukeshpanchal27 Apr 30, 2026
7e5a7d0
Merge branch 'trunk' into perf/10777
mukeshpanchal27 May 1, 2026
a331593
Refactor custom CSS support validation logic
mukeshpanchal27 May 1, 2026
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15 changes: 11 additions & 4 deletions src/wp-includes/block-supports/custom-css.php
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Original file line number Diff line number Diff line change
Expand Up @@ -14,15 +14,16 @@
* @return array The same parsed block with custom CSS class name added if appropriate.
*/
function wp_render_custom_css_support_styles( $parsed_block ) {
$block_type = WP_Block_Type_Registry::get_instance()->get_registered( $parsed_block['blockName'] );
// Check if the custom CSS attribute even exists.
$custom_css = $parsed_block['attrs']['style']['css'] ?? '';

if ( ! block_has_support( $block_type, 'customCSS', true ) ) {
if ( empty( trim( $custom_css ) ) ) {
return $parsed_block;
}

$custom_css = trim( $parsed_block['attrs']['style']['css'] ?? '' );
$block_type = WP_Block_Type_Registry::get_instance()->get_registered( $parsed_block['blockName'] );

if ( empty( $custom_css ) ) {
if ( ! block_has_support( $block_type, 'customCSS', true ) ) {
return $parsed_block;
}

Expand Down Expand Up @@ -79,6 +80,12 @@ function wp_enqueue_block_custom_css() {
*/
function wp_render_custom_css_class_name( $block_content, $block ) {
$class_string = $block['attrs']['className'] ?? '';

/* If there is no class string, there is no custom CSS class to add, so return early. */
if ( '' === $class_string ) {
return $block_content;
}

preg_match( '/\bwp-custom-css-\S+\b/', $class_string, $matches );

if ( empty( $matches ) ) {
Expand Down
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