Get WordPress AJAX URL

/**
 * Returns WordPress AJAX requests URL.
 *
 * E.g.: https://example.com/wp-admin/admin-ajax.php
 *
 * @see https://wpcodebook.com/wordpress-ajax-url/
 * @see https://developer.wordpress.org/plugins/javascript/ajax/#url
 * @see https://developer.wordpress.org/reference/functions/admin_url/
 */
function wpcodebook_ajax_url() {
	return admin_url( 'admin-ajax.php' );
}