RxDart #

About #

RxDart is a reactive functional programming library for Google Dart, based on ReactiveX.
Google Dart comes with a very decent Streams API out-of-the-box; rather than attempting to provide an alternative to this API, RxDart adds functionality on top of it.

How To Use RxDart #

For Example: Reading the Konami Code #

void main() {
  const konamiKeyCodes = const <int>[
    KeyCode.UP,
    KeyCode.UP,
    KeyCode.DOWN,
    KeyCode.DOWN,
    KeyCode.LEFT,
    KeyCode.RIGHT,
    KeyCode.LEFT,
    KeyCode.RIGHT,
    KeyCode.B,
    KeyCode.A];

  final result = querySelector('#result');
  final keyUp = new Observable<KeyboardEvent>(document.onKeyUp);

  keyUp
    .map((event) => event.keyCode)
    .bufferWithCount(10, 1)
    .where((lastTenKeyCodes) => const IterableEquality<int>().equals(lastTenKeyCodes, konamiKeyCodes))
    .listen((_) => result.innerHtml = 'KONAMI!');
}

API Overview #

RxDart's Observables extend the Stream class. This has two major implications:

• All methods defined on the Stream class exist on RxDart's Observables as well.
• All Observables can be passed to any API that expects a Dart Stream as an input.

Instantiation #

Generally speaking, creating a new Observable is either done by wrapping a Dart Stream using the top-level constructor new Observable(), or by calling a factory method on the Observable class. But to better support Dart's strong mode, combineLatest and zip have been pulled apart into fixed-length constructors. These methods are supplied as static methods, since Dart's factory methods don't support generic types.

Usage

var myObservable = new Observable(myStream);

Available Factory Methods

• amb
• concat
• defer
• error
• just
• merge
• never
• periodic
• retry
• timer

Usage

var myObservable = new Observable.merge([myFirstStream, mySecondStream]);

Available Static Methods

• combineLatest (combineLatest2, combineLatest3, combineLatest4, ..., combineLatest9)
• range
• tween
• zip (zip2, zip3, zip4, ..., zip9)

Usage

var myObservable = Observable.combineLatest3(
    myFirstStream, 
    mySecondStream, 
    myThirdStream, 
    (firstData, secondData, thirdData) => print("$firstData $secondData $thirdData"));

Transformations #

Available Methods

• bufferWithCount
• call
• concatMap
• concatWith
• debounce
• dematerialize
• flatMapLatest
• flatMap
• groupBy
• interval
• materialize
• mergeWith
• max
• min
• pluck
• repeat
• sample
• scan
• skipUntil
• startWith
• startWithMany
• takeUntil
• timeInterval
• timestamp
• throttle
• windowWithCount
• withLatestFrom
• zipWith

Usage

var myObservable = new Observable(myStream)
    .bufferWithCount(5)
    .distinct();

Objects #

• Observable
• BehaviourSubject
• ReplaySubject

Examples #

Web and command-line examples can be found in the example folder.

Web Examples #

In order to run the web examples, please follow these steps:

1. Clone this repo and enter the directory
2. Run pub get
3. Run pub serve example/web
4. Navigate to http://localhost:8080 in your browser

Command Line Examples #

In order to run the command line example, please follow these steps:

1. Clone this repo and enter the directory
2. Run pub get
3. Run dart example/bin/fibonacci.dart 10

Flutter Example #

Install Flutter

In order to run this repo, you must have Flutter installed. For help getting started with Flutter, view the online documentation.

Run the app

1. Open up an Android Emulator, the iOS Simulator, or connect an appropriate mobile device for debugging.
2. Open up a terminal
3. cd into the example/flutter/github_search directory
4. Run flutter doctor to ensure you have all Flutter dependencies working.
5. Run flutter packages get
6. Run flutter run

Notable References #

• Documentation on the Dart Stream class
• Tutorial on working with Streams in Dart
• ReactiveX (Rx)

Changelog #

Refer to the Changelog to get all release notes.