1. Dart
2. dart:html
3. StorageEvent
4. oldValue property

StorageEvent class

1. Constructors
2. StorageEvent
3. Properties
4. key
5. newValue
6. oldValue
7. storageArea
8. url
9. bubbles
10. cancelable
11. composed
12. currentTarget
13. defaultPrevented
14. eventPhase
15. hashCode
16. isTrusted
17. matchingTarget
18. path
19. runtimeType
20. target
21. timeStamp
22. type
23. Methods
24. composedPath
25. noSuchMethod
26. preventDefault
27. stopImmediatePropagation
28. stopPropagation
29. toString
30. Operators
31. operator ==

String get oldValue native;