Prototype of Dart proxies for JS objects.

pkg/element_created/lib/element_created.dart

Index: pkg/element_created/lib/element_created.dart
diff --git a/pkg/element_created/lib/element_created.dart b/pkg/element_created/lib/element_created.dart
new file mode 100644
index 0000000000000000000000000000000000000000..eb384705e734b9394b19c61cd55d486d2cc4b5f3
--- /dev/null
+++ b/pkg/element_created/lib/element_created.dart
@@ -0,0 +1,41 @@
+library element_created;
+
+import 'dart:js' as js;
+import 'dart:async';
+import 'dart:html' as dom;
+
+Stream<dom.Element> watch(String tagName, {String extendsTag}) {
+  var controller = new StreamController<dom.Element>(sync:true);
+  var params = {
+    'createdCallback': new js.JsFunction.withThis((self) {
+      controller.add(self);
+    }),
+  };
+  if (extendsTag != null) {
+    params['extends'] = extendsTag;
+  }
+  new js.JsObject.fromBrowserObject(dom.document)
+      .callMethod('registerElementCreatedWatcher', [
+          tagName, new js.JsObject.jsify(params)]);
+
+  return controller.stream;
+}
+
+bool get supported {
+  if (js.context == null) return true;
+
+  return new js.JsObject.fromBrowserObject(dom.document)
+      .hasProperty('registerElementCreatedWatcher');
+}
+
+Future ready = () {
+  if (supported) {
+    return new Future.value(true);
+  }
+  var script = new dom.ScriptElement()
+    ..src = '/packages/element_created/element_created.js';
+
+  var future = script.onLoad.first;
+  dom.document.head.append(script);
+  return future;
+}();