calling javascript from Dart

First add the js package as dependency in your pubspec.yaml :

dependencies:
  js: any

Then you can use your own js function myFunc() like that :

import 'package:js/js.dart' as js;

main() {
  js.context.myFunc();
}

js.context is an alias to javascript window.

See Using JavaScript from Dart: The js Library for more details.

Maybe my answer will be worth it for somebody, so that's why I'm posting a simple JS function call from Dart.

1. Add the js package dependency:

   dependencies:
     js: any
   

2. Create a JS file, let's say example.js:

   function test() {
     return 12+20;
   }
   

3. Add the example.js above inside index.html with the <script src="..."> tag.
4. Interop the function above from JS to Dart:

   @JS()
   library t;
   
   import 'package:js/js.dart';
   
   @JS()
   external int Test();
   
   class MyOwn {
     int get value => Test();
   }
   

5. And, in AngularDart's TODOLIST — which is default component available —:

   @override
   Future<Null> ngOnInit() async => print(MyOwn().value);