Add callback function in dart to jquery UI component

callBackToJS.dart

class CallbackFunction implements Function {
  final Function f;
  CallbackFunction(this.f);
  call() => throw new StateError('There should always been at least 1 parameter'
  '(js this).');
  noSuchMethod(Invocation invocation) {
    Function.apply(f, []);
  }
}

.callMethod("spinner", [new js.JsObject.jsify({
    "stop": new js.JsFunction.withThis(new CallbackFunction(recalc),
    "page": 1,
    "step": 0.1
    })])

void recalc(){
   print("recalcing");
}