WordPress: Get page ID from slug

wp-get_id_by_slug

// Usage:
// get_id_by_slug('any-page-slug','any-post-type');

function get_id_by_slug($page_slug, $slug_page_type = 'page') {
	$find_page = get_page_by_path($page_slug, OBJECT, $slug_page_type);
	if ($find_page) {
		return $find_page->ID;
	} else {
		return null;
	}
}