How do I create a global (on the window) object in

问题:

Let's say I want to create a global object called Hello and add the function world on that object, so that any other JavaScript library in the browser can simply call it with window.Hello.world();

How do I create such an object in Dart lang and how do I expose it / place it globally / on the window object?

In plain JavaScript, I would be able to write:

window.Hello = {
  world: function() {
    console.log("Hello World!");
  }
}

window.Hello.world();

But how do you do this in Dart?

回答1:

I work on Dart-JS interop. Here is the cleanest way to do it using the new package:js/js.dart interop.

@JS()
library your_library;

import 'package:js/js.dart';

@anonymous
@JS()
class HelloObject {
  external factory HelloObject({Function world});
  external world();
}

@JS()
external set Hello(HelloObject v);
@JS()
external HelloObject get Hello;

main() {
  Hello = new HelloObject(world: allowInterop(() { print("Hello from dart"); }));

  // You can also call this object from Dart as an added bonus.
  // For example you could call this from Dart or Js.
  /// Hello.world();
}

回答2:

I am not sure how it will work with objects, but if you want to do that for methods, it's quite simple:

import 'dart:js' as js;

main() {
  js.context['methodFromDart'] = doMyStuff;
}

void doMyStuff(String text) => print(text);

And then in you Javascript you are free to do:

methodFromDart("Hello world to Dart!");

You can try to find a way how to do similar things to objects.