Dart has all the pieces you need to write modern web apps:

Web UI lets you use future web APIs today, with support for proposed standards such as web components, MDV, and shadow DOM.

All modern browsers (both desktop and mobile) can run Dart web apps, thanks to our Dart-to-JavaScript compiler.

// Dart code:
import 'package:web_ui/web_ui.dart';

@observable String myString = '';

String get shouted => myString.toUpperCase();

String get palindrome =>
    myString + myString.split('').reversed.join();

<!-- HTML code: -->
<input type="text" bind-value="myString"
       placeholder="Type here">
  
<div> Shouted: {{shouted}} </div>
<div> Palindromic: {{palindrome}} </div>
    
<script type="application/dart" src="little.dart"></script>
<script src="packages/browser/dart.js"></script>