Dynamically load code with Dart thanks to spawnUri http://blog.sethladd.com/2013/04/dynamically-load-code-with-dart.html

main.dart

import 'dart:html';
import 'dart:isolate';

SendPort reverser;

void main() {
  reverser = spawnUri("https://gist.github.com/ggirou/6543763/raw/5be58e6aa28096e1e0f088112a59cbd2baab7719/test.dart");
  // reverser = spawnUri("test.dart");

  query('#button').onClick.listen(test);
}

test(_) {
  reverser.call("").then(print);
}

test.dart

import 'dart:isolate';

void main() {
  port.receive((msg, SendPort replyTo) {
    replyTo.send("Hello world!");
  });
}