1. Dart
2. dart:html
3. CustomElementRegistry
4. whenDefined method

CustomElementRegistry class

1. Properties
2. hashCode
3. runtimeType
4. Methods
5. define
6. get
7. whenDefined
8. noSuchMethod
9. toString
10. Operators
11. operator ==

Future whenDefined(String name) =>
    promiseToFuture(JS("", "#.whenDefined(#)", this, name));