Another update from ingydotnet^djgoku

Task/Animation/Dart/animation.dart

@@ -0,0 +1,26 @@
+import 'dart:html';
+import 'dart:async';
+
+const frameTime = const Duration(milliseconds: 100);
+
+void main() {
+  String text = "Hello World! ";
+  bool rotateRight = true;
+
+  Element writeHere =
+      querySelector('#output'); // assumes you have a pre with that ID
+  writeHere.onClick.listen((event) => rotateRight = !rotateRight);
+
+  new Timer.periodic(frameTime, (_) {
+    text = changeText(text, rotateRight);
+    writeHere.text = text;
+  });
+}
+
+String changeText(extt, rotateRight) {
+  if (rotateRight) {
+    return extt.substring(extt.length - 1) + extt.substring(0, extt.length - 1);
+  } else {
+    return extt.substring(1) + extt.substring(0, 1);
+  }
+}