WP_Hook::has_filter( string $hook_name = '', callable|string|array|false $callback = false )
Checks if a specific callback has been registered for this hook.
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.
Parameters
- $hook_name
-
(Optional) The name of the filter hook.
Default value: ''
- $callback
-
(Optional) The callback to check for.<br> This method can be called unconditionally to speculatively check a callback that may or may not exist.
Default value: false
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.
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;
}
Changelog
| Version | Description |
|---|---|
| 4.7.0 | Introduced. |