Question

I’ve been using a bit of code (by John Evans) to execute javascript from within Dart:

void injectJavascript(String javascript, [bool removeAfter = false]){
  var s = new Element.tag("script");
  s.attributes["type"] = "text/javascript";
  s.text = javascript;
  document.body.nodes.add(s);
  if (removeAfter != null && removeAfter)
    s.remove();
}

injectJavascript("alert('using javascript')");

But I haven’t been able to send or return variables. Is this currently possible? If not, any idea when it will become possible?

Answer 1

You will need to use postMessage to do this. For example if you have converted your variable into JSON then you can do this from inside Dart

window.postMessage(jsonMessage, “*”);

and then pick it up from the JavaScript side like this

function recieveMessage(event) {
  var message = JSON.parse(event.data);
  :
}
window.addEventListener("message", receiveMessage, false); 

If you need to work with more advanced things such as two way communication and callbacks then take a look at the code for DartGap in particular the DeviceMessageRouter class and the javascript integration layer.