1. Dart
2. dart:html
3. AnimationEffectTimingReadOnly
4. duration property

AnimationEffectTimingReadOnly class

1. Properties
2. delay
3. direction
4. duration
5. easing
6. endDelay
7. fill
8. iterations
9. iterationStart
10. hashCode
11. runtimeType
12. Methods
13. noSuchMethod
14. toString
15. Operators
16. operator ==

Object get duration native;