WordPress at a glance
filter is not described

block_default_classname filter-hook . WP 1.0

Filters the default block className for server rendered blocks.

Usage

add_filter( 'block_default_classname', 'filter_function_name_1383', 10, 2 );
function filter_function_name_1383( $class_name, $block_name ){
	// filter...

	return $class_name;
}
$class_name(string)
The current applied classname.
$block_name(string)
The block name.

Where the hook is called

wp_get_block_default_classname()
block_default_classname
wp-includes/block-supports/generated-classname.php 31
$classname = apply_filters( 'block_default_classname', $classname, $block_name );

Where in WP core the hook is used WordPress

Usage not found.