has_filter() – Checks if any filter has been registered for a hook.
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Description
Checks if any filter has been registered for a 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.
Usage
$bool|int = has_filter( $hook_name, $callback );
Parameters
- $hook_name
- ( string ) required – The name of the filter hook.
- $callback
- ( callable|string|array|false ) optional – Optional. The callback to check for. This function can be called unconditionally to speculatively check a callback that may or may not exist. Default false.
Returns
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 name: wordpress/wp-includes/plugin.php
Lines:
function has_filter( $hook_name, $callback = false ) { global $wp_filter; if ( ! isset( $wp_filter[ $hook_name ] ) ) { return false; } return $wp_filter[ $hook_name ]->has_filter( $hook_name, $callback ); }