react 4.9.1

Dart wrapper for React JS

Pub ReactJS v15.6.0 Build Status React Dart API Docs

Getting Started #

Installation #

If you are not familiar with the ReactJS library, read this react tutorial first.

  1. Install the Dart SDK

     brew install dart
  2. Create a pubspec.yaml file in the root of your project, and add react as a dependency:

     name: your_package_name
     version: 1.0.0
       sdk: ^2.0.0 
       react: ^4.5.0
  3. Install the dependencies using pub:

     pub get

Wire things up #


In a .html file where Include the native javascript react and react_dom libraries (provided with this library for compatibility reasons) within your .html file, and add an element with an id to mount your React component into.

Lastly, add the .js file that Dart will generate. The file will be the name of the .dart file that contains your main entrypoint, with .js at the end.

    <!-- ... -->
    <div id="react_mount_point">Here will be react content</div>
    <script src="packages/react/react.js"></script>
    <script src="packages/react/react_dom.js"></script>
    <script defer src="your_dart_file_name.dart.js"></script>

Note: When serving your application in production, use packages/react/react_with_react_dom_prod.js file instead of the un-minified react.js / react_dom.js files shown in the example above.

Dart App #

Once you have an .html file containing the necessary .js files, you can initialize React in the main entrypoint of your Dart application.

import 'dart:html';

import 'package:react/react_client.dart' as react_client;
import 'package:react/react.dart';
import 'package:react/react_dom.dart' as react_dom;

main() {
  // This should be called once at the beginning of the application.
  // Something to render... in this case a simple <div> with no props, and a string as its children.
  var component = div({}, "Hello world!");
  // Render it into the mount node we created in our .html file. 
  react_dom.render(component, querySelector('#react_mount_point'));

Build Stuff #

Using browser native elements #

If you are familiar with React (without JSX extension) React-dart shouldn't surprise you much. All elements are defined as functions that take props as first argument and children as optional second argument. props should implement Map and children is either one React element or List with multiple elements.

var aDiv = div({"className": "something"}, [
  h1({"style": {"height": "20px"}}, "Headline"),
  a({"href":""}, "Something"),
  "Some text"

For event handlers you must provide function that takes a SyntheticEvent (defined in this library).

var aButton = button({"onClick": (SyntheticMouseEvent event) => print(event)});

Defining custom components #

  1. Define custom class that extends Component and implements - at a minimum - render.

     // cool_widget.dart
     import 'package:react/react.dart';
     class CoolWidgetComponent extends Component {
       render() => div({}, "CoolWidgetComponent");
  2. Then register the class so ReactJS can recognize it.

     var CoolWidget = registerComponent(() => new CoolWidgetComponent());

    Warning: registerComponent should be called only once per component and lifetime of application.

  3. Then you can use the registered component similarly as native elements.

     // app.dart
     import 'dart:html';
     import 'package:react/react_client.dart' as react_client;
     import 'package:react/react.dart';
     import 'package:react/react_dom.dart' as react_dom;
     import 'cool_widget.dart';
     main() {
       // This should be called once at the beginning of the application.
       react_dom.render(CoolWidget({}), querySelector('#react_mount_point'));

Custom component with props #

// cool_widget.dart

import 'package:react/react.dart';

class CoolWidgetComponent extends Component {
  render() {
    return div({}, props['text']);

var CoolWidget = registerComponent(() => new CoolWidgetComponent());
// app.dart

import 'dart:html';

import 'package:react/react_client.dart' as react_client;
import 'package:react/react.dart';
import 'package:react/react_dom.dart' as react_dom;

import 'cool_widget.dart';

main() {
  // This should be called once at the beginning of the application.
  react_dom.render(CoolWidget({"text": "Something"}), querySelector('#react_mount_point'));

Custom component with a typed interface #

Note: The typed interface capabilities of this library are fairly limited, and can result in extremely verbose implementations. We strongly recommend using the OverReact package - which makes creating statically-typed React UI components using Dart easy.

// cool_widget.dart
typedef CoolWidgetType({String headline, String text, int counter});

var _CoolWidget = registerComponent(() => new CoolWidgetComponent());

CoolWidgetType CoolWidget({String headline, String text, int counter}) {
  return _CoolWidget({'headline':headline, 'text':text});

class CoolWidgetComponent extends Component {
  String get headline => props['headline'];
  String get text => props['text'];
  int get counter => props['counter'];
  render() {
    return div({}, 
      h1({}, headline),
      span({}, text),
      span({}, counter),
// app.dart

import 'dart:html';

import 'package:react/react_client.dart' as react_client;
import 'package:react/react.dart';
import 'package:react/react_dom.dart' as react_dom;

import 'cool_widget.dart';

void main() {
  // This should be called once at the beginning of the application.

        headline: "My custom headline",
        text: "My custom text",
        counter: 3,

React Component Lifecycle methods #

The Component class mirrors ReactJS' React.Component class, and contains all the same methods.

See: ReactJS Lifecycle Method Documentation for more information.

class MyComponent extends Component {
  void componentWillMount() {}
  void componentDidMount() {}
  void componentWillReceiveProps(Map nextProps) {}
  void componentWillUpdate(Map nextProps, Map nextState) {}
  void componentDidUpdate(Map prevProps, Map prevState) {}
  void componentWillUnmount() {}
  bool shouldComponentUpdate(Map nextProps, Map nextState) => true;
  Map getInitialState() => {};
  Map getDefaultProps() => {};
  render() => div({}, props['text']);

Using refs and findDOMNode #

The use of component refs in react-dart is a bit different from React JS.

  • You can specify a ref name in component props and then call ref method to get the referenced element.
  • Return values for Dart components, DOM components and JavaScript components are different.
    • For a Dart component, you get an instance of the Dart class of the component.
    • For primitive components (like DOM elements), you get the DOM node.
    • For JavaScript composite components, you get a ReactElement representing the react component.

If you want to work with DOM nodes of dart or JS components instead, you can call top level findDOMNode on anything the ref returns.

var DartComponent = registerComponent(() => new _DartComponent());
class _DartComponent extends Component {
  render() => div({});
  void someInstanceMethod(int count) {
    window.alert('count: $count');

var ParentComponent = registerComponent(() => new _ParentComponent());
class _ParentComponent extends Component {
  void componentDidMount() {
    InputElement input = ref("input"); // Returns the DOM node.
    print(input.value); // Prints "hello" to the console.

    _DartComponent dartComponentRef = ref("dartComponent"); // Returns instance of _DartComponent
    dartComponentRef.someInstanceMethod(5); // Calls the method defined in _DartComponent
    react_dom.findDOMNode(dartRef); // Returns div element rendered from _DartComponent

    react_dom.findDOMNode(this); // Returns root dom element rendered from this component
  render() {
    return div({},
      input({"ref": "input", "value": "hello"}),
      DartComponent({"ref": "dartComponent"}),

Example Application #

For more robust examples take a look at our examples.

Unit Testing Utilities #

lib/react_test_utils.dart is a Dart wrapper for the ReactJS TestUtils library allowing for unit tests to be made for React components in Dart.

Here is an example of how to use React TestUtils within a Dart test.

import 'package:test/test.dart';
import 'package:react/react.dart' as react;
import 'package:react/react_client.dart' as react_client;
import 'package:react/react_dom.dart' as react_dom;
import 'package:react/react_test_utils.dart' as react_test_utils;

class MyTestComponent extends react.Component {
  Map getInitialState() => {'text': 'testing...'};
  render() {
    return react.div({}, 
        react.button({'onClick': (_) => setState({'text': 'success'})}),
        react.span({'className': 'spanText'}, state['text']),

var myTestComponent = react.registerComponent(() => new MyTestComponent());

void main() {

  test('should click button and set span text to "success"', () {
    var component = react_test_utils.renderIntoDocument(myTestComponent({}));

    // Find button using tag name
    var buttonElement = react_test_utils.findRenderedDOMComponentWithTag(
        component, 'button');

    // Find span using class name
    var spanElement = react_test_utils.findRenderedDOMComponentWithClass(
        component, 'spanText');

    var buttonNode = react_dom.findDOMNode(buttonElement);
    var spanNode = react_dom.findDOMNode(spanElement);

    // Span text should equal the initial state
    expect(spanNode.text, equals('testing...'));

    // Click the button and trigger the onClick event;

    // Span text should change to 'success'
    expect(spanNode.text, equals('success'));

Contributing #

Format using

dartfmt -l 120 -w .

While we'd like to adhere to the recommended line length of 80, it's too too short for much of the code repo written before a formatter was use, causing excessive wrapping and code that's hard to read.

So, we us a line length of 120 instead.

Running Tests #

Dart 2: dart2js #

pub run test -p chrome

Or any other browser, e.g. -p firefox.

Dart 2: Dart Dev Compiler ("DDC") #

pub run build_runner test -- -p chrome

DDC only works in chrome.

Dart 1: Dart VM #

pub run test -p content-shell

Dart 1: dart2js #

pub run test -p chrome

Or any other browser platform, e.g. -p firefox.

Dart 1: Dart Dev Compiler ("DDC") #

  1. In one terminal, serve the test directory using the dev compiler:
     pub serve test --port=8090 --web-compiler=dartdevc
  2. In another terminal, run the tests, referencing the port the dev compiler is using to serve the test directory:
     pub run test -p chrome --pub-serve=8090
    DDC only works in chrome.

Building React JS Source Files #

After modifying dart_helpers.js, run:


4.9.1 #

  • #205 Fix context setter typing to match getter and not fail implicit_casts: false

4.9.0 #

  • #202 Add bindings for transition / animation events
  • #198 Updates in preparation for 5.0.0 release

4.8.1 #

  • #197 Fix Dart component callback refs with typed arguments not working in Dart 2 dynamic ref argument (worked):
      Foo({'ref': (ref) => _fooRef = ref})
    non-dynamic ref argument (did not work):
      Foo({'ref': (FooComponent ref) => _fooRef = ref})

4.8.0 #

  • #181: Remove unnecessary zoning on event handlers that interferes with testing
    • Handlers triggered by real events will now always be called in the root zone.

      In most cases, handlers were already running in the root zone, so this should not affect behavior. See #179 for more details.

    • When testing, you previous had to bind event handlers or callbacks triggered by event handlers to zones when using expect or expectAsync.

        var renderedInstance = renderIntoDocument(
          Button({}, {
            'onButtonPress': Zone.current.bindUnaryCallback(expectAsync((e) {
              // ...
            }, reason: 'onButtonPress not called')),
            'onClick': Zone.current.bindUnaryCallback((e) {
              expect(e.defaultPrevented, isTrue);
        // ...;

      Now, handlers will be called in the zone they're triggered from, which makes testing events easier and more predictable:

        var renderedInstance = renderIntoDocument(
          Button({}, {
            'onButtonPress': expectAsync((e) {
              // ...
            }, reason: 'onButtonPress not called'),
            'onClick': (e) {
              expect(e.defaultPrevented, isTrue);
        // ...;

4.7.1 #

  • #182: Deprecate emptyJsMap:
    • Use newObject() from dart:js_util instead

4.7.0 #

  • #162: Add jsifyAndAllowInterop, deprecate some obsolete JS utils:
    • Deprecate jsify, setProperty, and getProperty; use versions from dart:js_util instead
    • Deprecate EmptyObject; use newObject from dart:js_util instead
  • #170: Reformat with line length of 120 for better readability

4.6.2 #

  • #162: Important Deprecations

    These deprecations are being put in place to prepare consumers for the upcoming 5.0.0 release which will include support for React JS version 16.x

    • react_server.dart and Dart VM server-side rendering
      • Server-side rendering via react_dom_server.dart, though untested, is still in place
    • Legacy context APIs
    • isMounted
    • react_test_utils.SimulateNative
    • String Component.refs
    • Component.replaceStates
    • Component.bind
    • Component.transferComponentState
  • #155: Clean the lint trap.

4.6.1 #

4.6.0 #

  • #152: Format all files using dartfmt.
  • #153: New unconvertJsProps utility function.

4.5.0 #

  • Improvement: Dart 2 compatible!


Serving / Viewing React Dart Examples #

  1. Run pub get in your terminal.
  2. Run pub serve example --web-compiler=dartdevc.
  3. Open Chrome.
  4. Navigate to http://localhost:8080

Use this package as a library

1. Depend on it

Add this to your package's pubspec.yaml file:

  react: ^4.9.1

2. Install it

You can install packages from the command line:

with pub:

$ pub get

with Flutter:

$ flutter pub get

Alternatively, your editor might support pub get or flutter pub get. Check the docs for your editor to learn more.

3. Import it

Now in your Dart code, you can use:

import 'package:react/react.dart';
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Learn more about scoring.

We analyzed this package on Sep 17, 2019, and provided a score, details, and suggestions below. Analysis was completed with status completed using:

  • Dart: 2.5.0
  • pana: 0.12.21


Detected platforms: Flutter, web, other

No platform restriction found in primary library package:react/react.dart.

Health suggestions

Fix lib/react_test_utils.dart. (-17.34 points)

Analysis of lib/react_test_utils.dart reported 38 hints, including:

line 62 col 64: 'jsify' is deprecated and shouldn't be used.

line 64 col 70: 'jsify' is deprecated and shouldn't be used.

line 66 col 66: 'jsify' is deprecated and shouldn't be used.

line 68 col 56: 'jsify' is deprecated and shouldn't be used.

line 70 col 58: 'jsify' is deprecated and shouldn't be used.

Fix lib/react_client.dart. (-16.09 points)

Analysis of lib/react_client.dart reported 35 hints, including:

line 47 col 28: 'ref' is deprecated and shouldn't be used.

line 174 col 1: 'InteropContextValue' is deprecated and shouldn't be used.

line 175 col 28: 'InteropContextValue' is deprecated and shouldn't be used.

line 177 col 5: 'setProperty' is deprecated and shouldn't be used.

line 177 col 42: 'ReactDartContextInternal' is deprecated and shouldn't be used.

Fix lib/react.dart. (-9.08 points)

Analysis of lib/react.dart reported 19 hints, including:

line 38 col 35: 'ref' is deprecated and shouldn't be used.

line 47 col 81: 'getChildContext' is deprecated and shouldn't be used.

line 49 col 47: 'contextKeys' is deprecated and shouldn't be used.

line 133 col 10: 'ref' is deprecated and shouldn't be used.

line 142 col 10: 'nextContext' is deprecated and shouldn't be used.

Fix additional 9 files with analysis or formatting issues. (-7.35 points)

Additional issues in the following files:

  • lib/react_client/react_interop.dart (11 hints)
  • lib/react_client/js_interop_helpers.dart (3 hints)
  • lib/react_test.dart (1 hint)
  • lib/react_dom.dart (Run dartfmt to format lib/react_dom.dart.)
  • lib/react_dom_server.dart (Run dartfmt to format lib/react_dom_server.dart.)
  • lib/react_server.dart (Run dartfmt to format lib/react_server.dart.)
  • lib/src/ddc_emulated_function_name_bug.dart (Run dartfmt to format lib/src/ddc_emulated_function_name_bug.dart.)
  • lib/src/react_client/dart2_interop_workaround_bindings.dart (Run dartfmt to format lib/src/react_client/dart2_interop_workaround_bindings.dart.)
  • lib/src/react_client/event_prop_key_to_event_factory.dart (Run dartfmt to format lib/src/react_client/event_prop_key_to_event_factory.dart.)


Package Constraint Resolved Available
Direct dependencies
Dart SDK >=1.24.3 <3.0.0
js ^0.6.0 0.6.1+1
meta ^1.1.6 1.1.7
Dev dependencies
build_runner >=0.6.0 <2.0.0
build_test >=0.9.0 <1.0.0
build_web_compilers >=0.2.0 <3.0.0
dart2_constant ^1.0.0
dependency_validator ^1.2.0
test >=0.12.30 <2.0.0