The project is actively developed by Microsoft Open Technologies, Inc., in collaboration with a community of open source developers.
Applications, especially on the web have changed over the years from being a simple static page, to DHTML with animations, to the Ajax revolution. Each time, we're adding more complexity, more data, and asynchronous behavior to our applications. How do we manage it all? How do we scale it? By moving towards "Reactive Architectures" which are event-driven, resilient and responsive. With the Reactive Extensions, you have all the tools you need to help build these systems.
Using RxJS, you can represent multiple asynchronous data streams (that come from diverse sources, e.g., stock quote, tweets, computer events, web service requests, etc.), and subscribe to the event stream using the Observer object. The Observable notifies the subscribed Observer instance whenever an event occurs.
Because observable sequences are data streams, you can query them using standard query operators implemented by the Observable type. Thus you can filter, project, aggregate, compose and perform time-based operations on multiple events easily by using these operators. In addition, there are a number of other reactive stream specific operators that allow powerful queries to be written. Cancellation, exceptions, and synchronization are also handled gracefully by using the methods on the Observable object.
/* Get stock data somehow */var source = getStockData;sourcefilterreturn quoteprice > 30;mapreturn quoteprice;forEachconsole.log'Prices higher than $30: $' + price;;
Now what if this data were to come as some sort of event, for example a stream, such as as a WebSocket, then we could pretty much write the same query to iterate our data, with very little change.
/* Get stock data somehow */var source = getAsyncStockData;var subscription = sourcefilterreturn quoteprice > 30;mapreturn quoteprice;forEachconsole.log'Prices higher than $30: $' + price;console.log'Something went wrong: ' + errmessage;;/* When we're done */subscriptiondispose;
The only difference is that we can handle the errors inline with our subscription. And when we're no longer interested in receiving the data as it comes streaming in, we call
dispose on our subscription.
Sure, there are a lot of libraries to get started with RxJS? Confused on where to get started? Start out with the complete set of operators with
rx.all.js, then you can reduce it to the number of operators that you really need, and perhaps stick with something as small as
This set of libraries include:
rx.all.js- complete version of RxJS with all operators, minus the testing operators, and comes with a compat file for older browsers.
rx.lite.js- lite version with event bindings, creation, time and standard query operators with a compat file for older browsers. For most operations, this is the file you'll want to use unless you want the full power of RxJS.
rx.lite.extras.js- the operators missing from rx.lite.js that can be found in rx.js.
rx.js- core library for ES5 compliant browsers and runtimes plus compatibility for older browsers.
rx.aggregates.js- aggregation event processing query operations
rx.async.js- async operations such as events, callbacks and promises plus a compat file for older browsers.
rx.backpressure.js- backpressure operators such as pause/resume and controlled.
rx.binding.js- binding operators including multicast, publish, publishLast, publishValue, and replay
rx.coincidence.js- reactive coincidence join event processing query operations
rx.experimental.js- experimental operators including imperative operators and forkJoin
rx.joinpatterns.js- join patterns event processing query operations
rx.testing.js- used to write unit tests for complex event processing queries
rx.time.js- time-based event processing query operations
rx.virtualtime.js- virtual-time-based schedulers
To give you an idea about rich composition, we can create an autocompletion service which takes the user input from a text input and then query a service, making sure not to flood the service with calls for every key stroke, but instead allow to go at a more natural pace.
Next, we'll get the user input from an input, listening to the keyup event by using the
Rx.Observable.fromEvent method. This will either use the event binding from jQuery, Zepto, AngularJS, Backbone.js and Ember.js if available, and if not, falls back to the native event binding. This gives you consistent ways of thinking of events depending on your framework, so there are no surprises.
var $input = $'#input'$results = $'#results';/* Only get the value from each key up */var keyups = RxObservablefromEvent$input 'keyup'mapreturn etargetvalue;filterreturn textlength > 2;;/* Now debounce the input for 500ms */var debounced = keyupsdebounce500 /* ms */;/* Now get only distinct values, so we eliminate the arrows and other control characters */var distinct = debounceddistinctUntilChanged;
Now, let's query Wikipedia! In RxJS, we can instantly bind to any Promises A+ implementation through the
Rx.Observable.fromPromise method or by just directly returning it, and we wrap it for you.
return $ajaxurl: ''dataType: 'jsonp'data:action: 'opensearch'format: 'json'search: termpromise;
Once that is created, now we can tie together the distinct throttled input and then query the service. In this case, we'll call
flatMapLatest to get the value and ensure that we're not introducing any out of order sequence calls.
var suggestions = distinctflatMapLatestsearchWikipedia;
Finally, we call the
forEach method on our observable sequence to start pulling data.
suggestionsforEach$resultsemptyappend $mapdata1return $'<li>'textvalue;;$resultsemptyappend$'<li>'text'Error:' + error;;
And there you have it!
Please check out:
- The full documentation
- Our many great examples
- Our design guidelines
- Our contribution guidelines
- Our complete Unit Tests
- Everything else
- Don't Cross the Streams - Cascadia.js 2012 slides/demos | video
- Curing Your Asynchronous Blues - Strange Loop 2013 slides/demos | video
- Streaming and event-based programming using FRP and RxJS - FutureJS 2014 slides/demos | video
- Tyrannosaurus Rx - James Hughes
- Taming Asynchronous Workflows with Functional Reactive Programming - EuroClojure - Leonardo Borges slides | video
- Practical Rx with Matthew Podwysocki, Bart de Smet and Jafar Husain
- Netflix and RxJS
- Hello RxJS - Channel 9
- MIX 2011
- RxJS Today and Tomorrow - Channel 9
- Reactive Extensions Videos on Channel 9
- Adding Even More Fun to Functional Programming With RXJS - Ryan Anklam
- Reactive Angular - Devoxx France 2014 - Martin Gontovnikas
- Reactive Game Programming for the Discerning Hipster - JSConf 2014 - Bodil Stokke
You can use the
rx-cli to perform custom builds to create the RxJS you want:
$ rx --lite --compat --methods select,selectmany,takeuntil,fromevent
git clonecd ./rxjs
Installing with NPM
```bash` $ npm install rx $ npm install -g rx
### Using with Node.js and Ringo.js```jsvar Rx = require('rx');
Installing with Bower
$ bower install rxjs
Installing with Jam
$ jam install rx
Installing All of RxJS via NuGet
$ Install-Package RxJS-All
Install individual packages via NuGet:
Install-Package RxJS-All Install-Package RxJS-Lite Install-Package RxJS-Main Install-Package RxJS-Aggregates Install-Package RxJS-Async Install-Package RxJS-BackPressure Install-Package RxJS-Binding Install-Package RxJS-Coincidence Install-Package RxJS-Experimental Install-Package RxJS-JoinPatterns Install-Package RxJS-Testing Install-Package RxJS-Time
<!-- Just the core RxJS --><!-- Or all of RxJS minus testing --><!-- Or keeping it lite -->
require'paths':'rx': 'path/to/rx-lite.js''rx'var obs = RxObservableof42;obsforEach console.logx; ;;
In addition, we have support for common Node.js functions such as binding to callbacks and the
RxJS has been thoroughly tested against all major browsers and supports IE6+, Chrome 4+, FireFox 1+, and Node.js v0.4+.
You can contribute by reviewing and sending feedback on code checkins, suggesting and trying out new features as they are implemented, submit bugs and help us verify fixes as they are checked in, as well as submit code fixes or code contributions of your own. Note that all code submissions will be rigorously reviewed and tested by the Rx Team, and only those that meet an extremely high bar for both quality and design/roadmap appropriateness will be merged into the source.
Copyright (c) Microsoft Open Technologies, Inc. All rights reserved. Microsoft Open Technologies would like to thank its contributors, a list of whom are at https://github.com/Reactive-Extensions/RxJS/wiki/Contributors.
Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at
Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.