has_filter( string $tag, callable|bool $function_to_check = false )

Check if any filter has been registered for a hook.



(Required) The name of the filter hook.


(Optional) The callback to check for.

Default value: false


(false|int) If $function_to_check is omitted, returns boolean for whether the hook has anything registered. When checking a specific function, the priority of that hook is returned, or false if the function is not attached. When using the $function_to_check argument, this function may return a non-boolean value that evaluates to false (e.g.) 0, so use the === operator for testing the return value.


File: wp-includes/plugin.php

function has_filter($tag, $function_to_check = false) {
	global $wp_filter;

	if ( ! isset( $wp_filter[ $tag ] ) ) {
		return false;

	return $wp_filter[ $tag ]->has_filter( $tag, $function_to_check );


Version Description
WP-2.5.0 Introduced.