The heartbeat_nopriv_send filter allows you to modify the Heartbeat response sent when no $_POST data is passed.

It was added in 3.6.

It is evaluated in wp_ajax_nopriv_heartbeat in the wp-admin/includes/ajax-actions.php file.

heartbeat_nopriv_send accepts 2 arguments:

1. array|object $response The response object or array.
2. string $screen_id The screen id

Example:

There is no example for this filter yet. Have an idea for one? Submit an example.