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:

1 to 9 of 9
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 );
}
 

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