Dart Passing object literals
It's common practice in JavaScript to pass object literals to functions:
// JavaScript
printOptions({responsive: true});
Unfortunately we cannot pass Dart Map objects to JavaScript in these cases.What we have to do is create a Dart object that represents the object literal and contains all of its fields:
// Dart
@JS()
@anonymous
class Options {
external bool get responsive;
external factory Options({bool responsive});
}Note that the Options Dart class doesn't correspond to any JavaScript class. As such we must mark it with the @anonymous annotation.
Now we can create a stub for the original printOptions function and call it with a new Options object:
// Dart
@JS()
external printOptions(Options options);
printOptions(new Options(responsive: true));