Filters whether a dynamic sidebar is considered “active”.

$is_active_sidebar bool

Whether or not the sidebar should be considered "active".
In other words, whether the sidebar contains any widgets.

$index int|string

Index, name, or ID of the dynamic sidebar.

File: wp-includes/widgets.php. View all references

return apply_filters( 'is_active_sidebar', $is_active_sidebar, $index );