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Library to build Web User Interfaces in Dart inspired by React.

Virtual DOM

Virtual DOM simplifies the way to manage DOM mutations, just describe how your Component should look at any point in time.

uix library has a highly optimized virtual dom implementation, see benchmarks below.


Each time component is invalidated, it registers itself in the Scheduler, and Scheduler is responsible for updating Components.

Scheduler is running tasks that updates visual representation when the new frame is rendered.

It also provides different queues for read/write DOM batching with priorities. Example


  • Automatic management of Dart streams with addSubscription(StreamSubscription s), addTransientSubscription(StreamSubscription s) methods. Transient subscriptions simplifies the way to manage subscriptions the same way virtual dom simplifies DOM mutations, just describe which dependencies should be active at any point in time.
// Code from TodoMVC[Observable] example

$Entry() => new Entry();
class Entry extends Component<int> {
  updateState() {
    _entry = entryStore.get(data);

    // each time Component is invalidated, old subscription will be
    // automatically canceled, so we just register a new one when
    // something is changed.

    return true;
  • revisioned nodes for fast "dirty checking" of mutable data structures. Just update revision when data is changed and check if view has an older revision, for example:
class LineView extends Component<RichLine> {
  List<VNode> _fragments;

  set data(RichLine newData) {
    if (identical(data, newData)) {
      if (data.isNewer(this)) {
    } else {
      data_ = newData;

Quick Start


  • Dart SDK 1.9.1 or greater

1. Create a new Dart Web Project

2. Add uix library in pubspec.yaml file:

  uix: any

3. Install dependencies

$ pub get

4. Create web/index.html file:

<!DOCTYPE html>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Hello uix</title>
    <script type="application/dart" src="main.dart"></script>
    <script src="packages/browser/dart.js"></script>

5. Create web/main.dart file:

library main;

import 'dart:html' as html;
import 'package:uix/uix.dart';

// Function to create new Box instances, it is used as an argument for
// virtual nodes that represent components.
// In the future, when metaclasses will be implemented in Dart, it
// won't be necessary to create this functions. Right now it is just a
// convention that will make it easier to migrate in the future by
// removing '$' prefix in all 'vComponent' invocations.
$Box() => new Box();

// Component<T> type parameter is used to specify type of the input data
// (props in React terms).
class Box extends Component<String> {
  // Tag name of the root element for this Component. Default tag 'div'.
  final tag = 'span';

  // Each time when Component is invalidated (new data is passed,
  // or invalidate() method is called), it will be updated during
  // writeDom phase.
  // API is designed this way intentionally to improve developer
  // experience and get better stack traces when something is
  // failing, that is why there is no method like render() in
  // React.
  updateView() {
    // updateRoot method is used to update internal representation
    // using Virtual DOM API.
    // vRoot node is used to represent root element.
    // Call operator is overloaded for all virtual nodes and is used
    // to assign children, it accepts Lists, Iterables, VNodes and
    // Strings.

class Main extends Component<String> {
  updateView() {
      vElement('span')('Hello '),
      vComponent($Box, data: data)

main() {
  // Initialize uix library.

  final component = new Main()..data = 'uix';

  // Inject component into document body.
  injectComponent(component, html.document.body);


VDom Benchmark

DBMonster Benchmark

Server-Side rendering

uix library with simple tweaks is fully capable to render components on the server and mounting on top of the existing html tree. Unfortunately Dart doesn't support any usable way to build uix Components this way. There are several proposals for Configured Imports 1 2 3 that will solve some problems, but it is still not enough to provide a good developer experience for users of this library. Conditional compilation will be way much better to write "isomorphic" Components.


The uix library. [...]