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

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

Parameters

$tag

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

Default value: ''

$function_to_check

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

Default value: false

Return

(bool|int) The priority of that hook is returned, or false if the function is not attached.

Source

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

public function has_filter( $tag = '', $function_to_check = false ) {
		if ( false === $function_to_check ) {
			return $this->has_filters();
		}

		$function_key = _wp_filter_build_unique_id( $tag, $function_to_check, false );
		if ( ! $function_key ) {
			return false;
		}

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

		return false;
	}

Uses

Uses	Description
wp-includes/class-wp-hook.php: WP_Hook::has_filters()	Checks if any callbacks have been registered for this hook.
wp-includes/plugin.php: _wp_filter_build_unique_id()	Build Unique ID for storage and retrieval.

Changelog

Version	Description
4.7.0	Introduced.

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Licensed under the GNU GPLv2+ License.
https://developer.wordpress.org/reference/classes/wp_hook/has_filter