WP_Hook::has_filter()publicWP 4.7.0

Checks if a specific callback has been registered for this hook.

When using the $callback 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.

{} It's a method of the class: WP_Hook{}

No Hooks.


true|false|Int. If $callback 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.


$WP_Hook = new WP_Hook();
$WP_Hook->has_filter( $hook_name, $callback );
The name of the filter hook.
Default: ''
The callback to check for. This method can be called unconditionally to speculatively check a callback that may or may not exist.
Default: false


Since 4.7.0 Introduced.

Code of WP_Hook::has_filter() WP 6.0

public function has_filter( $hook_name = '', $callback = false ) {
	if ( false === $callback ) {
		return $this->has_filters();

	$function_key = _wp_filter_build_unique_id( $hook_name, $callback, false );

	if ( ! $function_key ) {
		return false;

	foreach ( $this->callbacks as $priority => $callbacks ) {
		if ( isset( $callbacks[ $function_key ] ) ) {
			return $priority;

	return false;