has_action() │ WP 2.5.0

Check if any action 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.

No Hooks.

Return

true|false|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.

Usage

has_action( $hook_name, $callback );

$hook_name(string) (required)

The name of the action hook.

$callback(callable|string|array|false)

The callback to check for. This function can be called unconditionally to speculatively check a callback that may or may not exist.
Default: false