Looks like the issue is that I left out a script tag:

 <script src="packages/browser/interop.js"></script>

The documentation for 'package:js/js.dart' explains this, but the 'dart:js' library's documentation doesn't.

(Also, perhaps improve the error message for this case?)

Additional issues:
  - The documentation refers to features that are aren't in this library. For example, Callback.once doesn't exist.
  - It looks like there's no longer a way to free a proxy?
  - Contrary to the documentation, DOM nodes can't be passed between Dart and JavaScript. (They end up as Dart proxies and JS proxies.)
 
Also, a feature request: instead of:

   var jsElt = js.context["document"].callMethod("getElementById", [id]);

It seems like it might be nice to write it as:

  var jsElt = js.context.callMethod("document.getElementById", [id]);

This might even be more efficient, since there would only be one round trip and no intermediate proxies would need to be created. Perhaps array access could be implemented as well, sort of like using query() to find a DOM node.

(I can break those out into bugs if needed, but it sounds like this library is going to change anyway.)

Set owner to @justinfagnani.
Added Area-Library, Triaged labels.

This comment was originally written by @a14n

Comments on your additional issues :
 - There are some CL which are waiting before cleaning the doc.
 - One goal of "dart:js" was to get rid of scopes. However in Dartium this will cause memory leaks for now.
 - Unlike package:js the DOM nodes are not directly converted between Dart and JS (that has been done to reduce the generated js output)

On your feature request : with this syntax there could be some edge cases to handle. For instance if a "document.getElementById" variable had been defined ( e.g. window["document.getElementById"] = function(){return 1;}; ). Perhaps something like js.context.callMethodOn(["a", "b", "c"], methodName, args) for a.b.c.methodName(args).

There is also a CL to add Array support that is waiting to be merged (https://chromiumcodereview.appspot.com/23291005/).

Added Library-JS label.

Hi,

Is this issue still valid?

The original bug? no.

There is a possible feature request with passing path/index expressions to callMethod().