WordPress at a glance
filter is not described

theme_scandir_exclusions filter-hook . WP 4.7.4

Filters the array of excluded directories and files while scanning theme folder.

Usage

add_filter( 'theme_scandir_exclusions', 'filter_function_name_346' );
function filter_function_name_346( $exclusions ){
	// filter...

	return $exclusions;
}
$exclusions(array)
Array of excluded directories and files.

Where the hook is called

WP_Theme::scandir()
theme_scandir_exclusions
wp-includes/class-wp-theme.php 1147
$exclusions = (array) apply_filters( 'theme_scandir_exclusions', array( 'CVS', 'node_modules', 'vendor', 'bower_components' ) );

Where the hook is used (in WP core)

Does not used.