1. Dart
2. dart:html
3. BeforeUnloadEvent
4. returnValue property

##### BeforeUnloadEvent class

1. Properties
2. bubbles
3. cancelable
4. composed
5. currentTarget
6. defaultPrevented
7. eventPhase
8. hashCode
9. isTrusted
10. matchingTarget
11. path
12. returnValue
13. runtimeType
14. target
15. timeStamp
16. type
17. Methods
18. composedPath
19. noSuchMethod
20. preventDefault
21. stopImmediatePropagation
22. stopPropagation
23. toString
24. Operators
25. operator ==

description

# returnValue property Null safety

String? returnValue

## Implementation

    String? get returnValue native;

void returnValue= (String? value)

## Implementation

    set returnValue(String? value) native;