1. Dart
2. dart:html
3. Node
4. isConnected property

Node class

1. Properties
2. baseUri
3. childNodes
4. firstChild
5. isConnected
6. lastChild
7. nextNode
8. nodeName
9. nodes
10. nodeType
11. nodeValue
12. ownerDocument
13. parent
14. parentNode
15. previousNode
16. text
17. hashCode
18. on
19. runtimeType
20. Methods
21. append
22. clone
23. contains
24. getRootNode
25. hasChildNodes
26. insertAllBefore
27. insertBefore
28. remove
29. replaceWith
30. toString
31. addEventListener
32. dispatchEvent
33. noSuchMethod
34. removeEventListener
35. Operators
36. operator ==
37. Constants
38. ATTRIBUTE_NODE
39. CDATA_SECTION_NODE
40. COMMENT_NODE
41. DOCUMENT_FRAGMENT_NODE
42. DOCUMENT_NODE
43. DOCUMENT_TYPE_NODE
44. ELEMENT_NODE
45. ENTITY_NODE
46. ENTITY_REFERENCE_NODE
47. NOTATION_NODE
48. PROCESSING_INSTRUCTION_NODE
49. TEXT_NODE

bool get isConnected native;