wp_apply_custom_classname_support() │ WP 5.6.0

Adds the custom classnames to the output.

Internal function — this function is designed to be used by the kernel itself. It is not recommended to use this function in your code.

No Hooks.

Returns

Array. Block CSS classes and inline styles.

Usage

wp_apply_custom_classname_support( $block_type, $block_attributes );
$block_type(WP_Block_Type) (required)
Block Type.
$block_attributes(array) (required)
Block attributes.

Changelog

Since 5.6.0 Introduced.

wp_apply_custom_classname_support() code WP 7.0

wp-includes/block-supports/custom-classname.php 
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;
}