WP_Hook::has_filter( string $hook_name = '', callable|false $callback = false )

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

Description Description

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.

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Parameters Parameters


(string) (Optional) The name of the filter hook.

Default value: ''


(callable|false) (Optional) The callback to check for.

Default value: false

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Return Return

(bool|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.

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Source Source

File: wp-includes/class-wp-hook.php

	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;

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Changelog Changelog

Version Description
4.7.0 Introduced.

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