is_active_widget()

is_active_widget() — Determines whether a given widget is displayed on the front end. Either $callback or $id_base can be used. $id_base is the first argument when extending WP_Widget class. Without the optional $widget_id parameter, returns the ID of the first sidebar in which the first instance of the widget with the given callback or $id_base is found. With the $widget_id parameter, returns the ID of the sidebar where the widget with that callback/$id_base AND that ID is found. NOTE: $widget_id and $id_base are the same for single widgets. To be effective this function has to run after widgets have initialized, at action {

Inputs: $callback (callable|false): Optional. Widget callback to check. Default false. $widget_id (string|false): Optional. Widget ID. Optional, but needed for checking. Default false. $id_base (string|false): Optional. The base ID of a widget created by extending WP_Widget. Default false. $skip_inactive (bool): Optional. Whether to check in ‘wp_inactive_widgets’. Default true.

Returns string|false: ID of the sidebar in which the widget is active, false if the widget is not active.