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RxDart

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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.

Available Top-level Method

• observable

Usage

var myObservable = new Observable(myStream);

Available Factory Methods

• amb
• concat
• defer
• error
• just
• merge
• never
• periodic
• range (static)
• timer
• tween (static)

Usage

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

Available Static Methods

• combineLatest (combineLatest2, combineLatest3, combineLatest4, ..., combineLatest9)
• 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
• retry
• sample
• scan
• skipUntil
• startWith
• startWithMany
• takeUntil
• timeInterval
• timestamp
• throttle
• windowWithCount
• withLatestFrom
• zipWith

Usage

var myObservable = observable(myStream)
    .bufferWithCount(5)
    .distinct();

Objects

• Observable
• BehaviourSubject
• ReplaySubject

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.