1. Dart
2. dart:html
3. ApplicationCache
4. onChecking property

##### ApplicationCache class

1. Properties
2. hashCode
3. on
4. onCached
5. onChecking
6. onDownloading
7. onError
8. onNoUpdate
9. onObsolete
10. onProgress
11. onUpdateReady
12. runtimeType
13. status
14. Methods
15. abort
16. addEventListener
17. dispatchEvent
18. noSuchMethod
19. removeEventListener
20. swapCache
21. toString
22. update
23. Operators
24. operator ==
25. Static properties
26. supported
27. Constants
28. cachedEvent
29. CHECKING
30. checkingEvent
31. DOWNLOADING
32. downloadingEvent
33. errorEvent
34. IDLE
35. noUpdateEvent
36. OBSOLETE
37. obsoleteEvent
38. progressEvent
39. UNCACHED
40. UPDATEREADY
41. updateReadyEvent

description

# onChecking property Null safety

Stream<Event> onChecking

Stream of `checking` events handled by this ApplicationCache.

## Implementation

    Stream<Event> get onChecking => checkingEvent.forTarget(this);