wp_register_sidebar_widget()

wp_register_sidebar_widget() — Registers an instance of a widget. The default widget option is ‘classname’ that can be overridden. The function can also be used to un-register widgets when $output_callback parameter is an empty string.

Inputs: $id (int|string): Widget ID. $name (string): Widget display title. $output_callback (callable): Run when widget is called. $options (array): Optional. An array of supplementary widget options for the instance. Field $classname (string): Class name for the widget’s HTML container. Default is a shortened version of the output callback name. Field $description (string): Widget description for display in the widget administration panel and/or theme. Field $show_instance_in_rest (bool): Whether to show the widget’s instance settings in the REST API. Only available for WP_Widget based widgets.