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Dealing with streams using RxJs
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Hugo Cordier
June 05, 2015
Programming
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Dealing with streams using RxJs
Hugo Cordier
June 05, 2015
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Transcript
Dealing with Streams using RxJS
Hello! I am Hugo Cordier Developer and CTO at Melusyn
Melusyn helps film makers to manage and organize their productions. You can find me at : @HugoCrd We are hiring! Drop me a line at hugo@melusyn.com ♥
1. What’s an event? Javascript is about events
What’s an event? DOM events clicks, moves, focuses, drags events
What’s an event? Async response Ajax, Websocket events
What’s an event? Timeout, interval Time related events
What’s an event? Solution Callbacks & Promises
2. What’s a stream? Give me use-cases!
What’s a stream? A stream is a group of events
What’s a stream? Double clicks How fast can you click?
What’s a stream? Keyboard Konami code is a must have
feature
What’s a stream? Synchronizing async responses Requesting several services
What’s a stream? Solution Reactive Extensions
3. What to do with it?
What to do with it? Transforming events in the Stream
What to do with it? Merging, mixing Several streams
What to do with it? Dealing with time Delaying events,
creating interval, ...
4. The Rx Model Observables and Operators
The Rx Model A stream is an Observable An Observable
push down events through Operators
The Rx Model Operators transform a stream They can be
used to transform, filter and mix events from an Observable
The Rx Model
The Rx Model
The Rx Model myObservable .map(value => value+1) .filter(value => value
> 2) Finally some code!
The Rx Model
The Rx Model myObservable .merge(anotherObservable) .map(value => value+1) .filter(value =>
value > 2)
The Rx Model
The Rx Model myObservable .flatMap(anotherObservable) .map(value => value+1)//Values from anotherObservable
.filter(value => value > 2)
There’s a whole bunch of Operators The Rx Model http://reactivex.io/documentation/operators.html
5. The Rx Model Subscribing and dealing with errors
An Observable needs to be subscribed The Rx Model The
stream will flow once it has been subscribed
The Rx Model myObservable .subscribe( value => console.log(“Event”+value), e =>
console.error(e) )
6. The Rx Model Creating Observables
How to create an Observable? The Rx Model
The Rx Model Rx.Observable .just(1) .from([1,5,0,12,4]) .fromEvent(domElement, event) .fromNodeCallback(nodeFct) .fromPromise(promise)
.interval(2000)
The Rx Model Rx.Observable.create(s => { for (value in values)
{ s.onNext(value) } s.onCompleted() })
7. In real life
In real life Live search Using Google Geocoder and RxJS
http://codepen.io/HugoCrd/pen/vOxQvM
In real life Composing streams Aggregate data from several requests
http://codepen.io/HugoCrd/pen/azGxdW
In real life Realtime statistics Ping a server each x
seconds and diplay results http://codepen.io/HugoCrd/pen/dPeaLY
8. In real life RxJS is just a library. Use
it with whatever you want
In real life with... Node.js Node uses Callbacks. They can
easily be used as a stream var rename = Rx.Observable.fromNodeCallback(fs.rename); rename('file1.txt', 'file2.txt') .map(...) .subscribe(...)
In real life with... Angular.js Angular $watch is a stream
of model changes Angular also has an eventbus system : events on a handler are a stream Rx.Observable.$watch(scope, 'name') .map(...) .subscribe(...)
In real life with... Backbone.js Binding to an object is
listening to it’s changes. This could be used as a stream. Rx.Observable.fromEvent(object, ‘click’) .map(...) .subscribe(...)
In real life with... JS Wokers A worker could post
messages to into stream Rx.DOM.fromWebWorker('worker.js') .map(...) .subscribe(...)
Thanks! Any questions? We are hiring! Drop me a line
at hugo@melusyn.com or @HugoCrd ♥
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