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

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;
	}