How to call a Dart function from JavaScript

Question

My company has a very buggy fat client application written in JavaScript. As usual with a large JavaScript application, the code is rapidly becoming unmanageable.

I personally believe that writing in Dart would be a much better solution. But the 'start again' approach to management will not work.

I known that one can call JavaScript code from Dart, but is it possible to call Dart code from JavaScript?

This would allow us to incrementally replace the more critical libraries with Dart versions and still be able to use the original code base.

Answer 1

You should try Dart's JS interop library.

You can define a callback function inside Dart and export it (in a way) to JavaScript.

Take a look at this example:

Dart code defines JS function

 context['javascriptFunctionName'] = (parameter) {
       //call any Dart method
    }

then call it from JavaScript:

javascriptFunctionName({'param': 'value'});

Answer 2

With package js instead of dart:js it can be made available to JS this way:

import 'dart:html';
import 'package:js/js_util.dart';

void main() {
  setProperty(window, 'callDartFunc', allowInterop(dartFunc));
}

String dartFunc() => 'Hello World';

Thanks to Matan Lurey https://gitter.im/dart-lang/TALK-general?at=585b9b42db9cafe9183a3345