WordPress Is Category or Subcategory

is_category_or_subcategory.php

function is_category_or_subcategory($targetcategory) {

	if ( is_category() ) :

		// echo '<p>the target slug is: '. $targetcategory . '.</p>';

		$targetid = get_category_by_slug($targetcategory);
		// echo '<p>the target id is: '. $targetid->term_id . '.</p>';

		$targetid = strval($targetid->term_id);

		$id = get_query_var('cat');
		// echo '<p>this id is: '. $id . '.</p>';

		$chain = mca_category_parents($id);

		// print_r($chain);
		
		if ( in_array_r($targetid, $chain) ) {
			// echo '<p>found</p>';			
			return true;
		} else {
			// echo '<p>not found</p>';				
			return false;
		}

	endif;

}

function mca_category_parents($id, 	$chain = array() ) {

	$parent = get_category( $id );

	if ( is_wp_error( $parent ) ) return $parent;


	if ( $parent->parent && ( $parent->parent != $parent->term_id ) ) {
		$chain[] = mca_category_parents( $parent->parent);
	}

	$chain[] = $parent->term_id;

	return $chain;
	
}

function in_array_r($needle, $haystack, $strict = true) {
    foreach ($haystack as $item) {
        if (($strict ? $item === $needle : $item == $needle) || (is_array($item) && in_array_r($needle, $item, $strict))) {
            return true;
        }
    }

    return false;
}