1. Dart
2. dart:html
3. Console
4. warn method

Console class

1. Properties
2. memory
3. hashCode
4. runtimeType
5. Methods
6. assertCondition
7. clear
8. count
9. debug
10. dir
11. dirxml
12. error
13. group
14. groupCollapsed
15. groupEnd
16. info
17. log
18. markTimeline
19. profile
20. profileEnd
21. table
22. time
23. timeEnd
24. timeStamp
25. trace
26. warn
27. noSuchMethod
28. toString
29. Operators
30. operator ==

void warn(Object arg) =>
    _isConsoleDefined ? JS('void', 'window.console.warn(#)', arg) : null;