1. Dart
2. dart:html
3. WindowClient
4. visibilityState property

##### WindowClient class

1. Properties
2. focused
3. frameType
4. hashCode
5. id
6. runtimeType
7. type
8. url
9. visibilityState
10. Methods
11. focus
12. navigate
13. noSuchMethod
14. postMessage
15. toString
16. Operators
17. operator ==

description

# visibilityState property Null safety

String? visibilityState

## Implementation

    String? get visibilityState native;