The standard documentation for Dart and JavaScript interoperability isn’t great. It refers to the ‘dart:js’ library which although works is a bit verbose to get things done.
For instance, to call a jQuery function, you would need
import 'dart:js';...
context.callMethod(r'$', ['.some.class.selector']).callMethod('someFunction');
...
The dart team has since then released the js package with which you can simply call
import 'package:js/js.dart';...
context.$('.some.class.selector').someFunction();
...
Basically native syntax. Of course you have to add it to the yaml and pub get again.