attributes ) { $block_type->attributes = array(); } if ( ! array_key_exists( 'className', $block_type->attributes ) ) { $block_type->attributes['className'] = array( 'type' => 'string', ); } } } /** * Adds the custom classnames to the output. * * @since 5.6.0 * @access private * * @param WP_Block_Type $block_type Block Type. * @param array $block_attributes Block attributes. * * @return array Block CSS classes and inline styles. */ function wp_apply_custom_classname_support( $block_type, $block_attributes ) { $has_custom_classname_support = block_has_support( $block_type, 'customClassName', true ); $attributes = array(); if ( $has_custom_classname_support ) { $has_custom_classnames = array_key_exists( 'className', $block_attributes ); if ( $has_custom_classnames ) { $attributes['class'] = $block_attributes['className']; } } return $attributes; } // Register the block support. WP_Block_Supports::get_instance()->register( 'custom-classname', array( 'register_attribute' => 'wp_register_custom_classname_support', 'apply' => 'wp_apply_custom_classname_support', ) );