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<!doctype html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no">
<title>RxJS</title>
<link rel="stylesheet" href="css/reveal.css">
<link rel="stylesheet" href="css/theme/black.css">
<!-- Theme used for syntax highlighting of code -->
<link rel="stylesheet" href="lib/css/zenburn.css">
<!-- Printing and PDF exports -->
<script>
var link = document.createElement( 'link' );
link.rel = 'stylesheet';
link.type = 'text/css';
link.href = window.location.search.match( /print-pdf/gi ) ? 'css/print/pdf.css' : 'css/print/paper.css';
document.getElementsByTagName( 'head' )[0].appendChild( link );
</script>
</head>
<body>
<div class="reveal">
<div class="slides">
<section>
<h2>Reactive Extentions</h2>
RxJS
</section>
<section>
Focus is on RxJS, but is available for a lot of other languages including Java, .Net, C++ and swift
</section>
<section>
<img class="stretch" data-src="content/whaaat.gif">
</section>
<section>
<h2>Data flow</h2>
RxJS is a library for reactive programming using Observables, to make it easier to compose asynchronous or callback-based code
<br /><br />
<h2 class="fragment">
Observable pattern
</h2>
</section>
<!-- <section>
<table>
<thead>
<tr>
<th></th>
<th>Single</th>
<th>Multiple</th>
</tr>
</thead>
<tbody>
<tr>
<td>Pull</td>
<td>Function</td>
<td>Iterator</td>
</tr>
<tr>
<td>Push</td>
<td>Promise</td>
<td></td>
</tr>
</tbody>
</table>
</section> -->
<section>
<h1>Pull</h1>
</section>
<section>
Function
<pre><code class="TypeScript" data-trim contenteditable>
function myFunction(someVal){
return someVal*2
}
myFunction(5) // 10
</code></pre>
</section>
<section>
Iterators and generators
<pre><code class="TypeScript" data-trim contenteditable>
function* myFunction() {
yield 5;
yield 10;
yield 15;
}
var generator = myFunction();
console.log(generator.next().value);
console.log(generator.next().value);
console.log(generator.next().value);
</code></pre>
</section>
<section>
<h1>Push</h1>
</section>
<section>
<section>
Promise
<pre><code class="TypeScript" data-trim contenteditable>
let willIGetNewPhone = new Promise((resolve, reject) => {
setTimeout(() => {
resolve(true)
}, 1000)
});
willIGetNewPhone.then(value => {
console.log("Got a new phone!") //prints after 1 sec
});
</code></pre>
</section>
</section>
<img class="fragment" class="stretch" data-src="content/broken.gif">
<section>
<table>
<thead>
<tr>
<th></th>
<th>Single</th>
<th>Multiple</th>
</tr>
</thead>
<tbody>
<tr>
<td>Pull</td>
<td>Function</td>
<td>Iterator</td>
</tr>
<tr>
<td>Push</td>
<td>Promise</td>
<td class="fragment">Observable</td>
</tr>
</tbody>
</table>
</section>
<section>
Now entering RxJS<br />
<img class="fragment" class="stretch" data-src="content/rxjs.gif">
</section>
<section>
<section>
Observable
<pre><code class="TypeScript" data-trim contenteditable>
var myObservable = new Observable(observer => {
observer.next(42); //"return" a value instantly
setTimeout(() => {
observer.next(200); // "return" a value asynchronously
}, 1000);
});
myObservable.subscribe(next => {
console.log(next)
});
</code></pre>
</section>
<section>
Promises vs Observable syntax
<pre><code class="TypeScript" data-trim contenteditable>
promise.then(
successFunction
errorFunction
)
observable.subscribe(
nextFunction
errorFunction,
completeFunction
)
</code></pre>
</section>
<section>
Observable and observers<br />
Observers subscribe to observables
<pre><code class="TypeScript" data-trim contenteditable>
let myObservable = new Observable(.....) //observable
myObservable.subscribe(....) // Observer
myObservable.subscribe(....) // Observer
myObservable.subscribe(....) // Observer
</code></pre>
</section>
<section>
Multiple subscribes
<pre><code class="TypeScript" data-trim contenteditable>
var myObservable = new Observable(observer => {
observer.next(42);
setTimeout(() => {
observer.next(200);
}, 1000);
});
myObservable.subscribe(next => {
console.log("S1:" + next)
});
myObservable.subscribe(next => {
console.log("S2:" + next)
});
</code></pre>
</section>
<section>
Multiple subscribes shared
<pre><code class="TypeScript" data-trim contenteditable>
var myObservable = new Observable(observer => {
observer.next(42);
setTimeout(() => {
observer.next(200);
}, 1000);
}).share();
myObservable.subscribe(next => {
console.log("S1:" + next)
});
myObservable.subscribe(next => {
console.log("S2:" + next) //42 is never received
});
</code></pre>
</section>
</section>
<section>
<!-- "hot" vs "cold" observables<br /><br /> -->
.subscribe() and unSubscribe()
<pre><code class="TypeScript" data-trim contenteditable>
observable.subscribe(nextHandler, errorHandler, completionHandler)
let subscription = observable.subscribe(......)
subscription.unsubscribe()
</code></pre>
</section>
<section>
<section>
Creating Observables
</section>
<section>
.of(.....)
<pre><code class="TypeScript" data-trim contenteditable>
let myObservable = Observable.of(1, 2, 3);
myObservable.subscribe(next => {
console.log(next) //1, 2, 3
})
</code></pre>
</section>
<section>
.fromEvent(element, evenet)
<pre><code class="TypeScript" data-trim contenteditable>
Observable.fromEvent(window, 'mousemove')
.subscribe(next => {
console.log("Mouse movement")
});
</code></pre>
</section>
<section>
.interval(time_ms)
<pre><code class="TypeScript" data-trim contenteditable>
let myObservable = Observable.interval(300);
myObservable.subscribe(next => {
console.log(next) //0, 1, 2, 3....
})
</code></pre>
</section>
<section>
Creating your own
<pre><code class="TypeScript" data-trim contenteditable>
const myObservable = new Observable(observer => {
let counter = 0;
let interval = setInterval(() => {
observer.next( counter++ );
}, 300);
return () => { clearInterval(interval) }
});
myObservable.subscribe(next => {
console.log(next) // 0, 1, 2, 3.....
})
</code></pre>
</section>
</section>
<section>
Streams and time axis<br />
<img class="stretch" data-src="content/stream.png">
</section>
<section>
<section>
Operators
<pre><code class="TypeScript" data-trim contenteditable>
myObservable/mySubject
.
.subscribe
.map()
.filter()
.skip()
.delay()
.throttleTime()
.debounceTime()
.switchMap()
.retry()
.catch()
</code></pre>
</section>
<section>
<a href="http://reactivex.io/documentation/operators/map.html" target="_blank">.map(function)</a>
<img class="stretch" data-src="content/operators/map.png">
</section>
<section>
.filter(function)
<img class="stretch" data-src="content/operators/filter.png">
</section>
<section>
.skip(number)<br />
.take(number)
<img class="stretch" data-src="content/operators/skip.png">
</section>
<section>
.delay(ms)
<img class="stretch" data-src="content/operators/delay.png">
</section>
<section>
.throttleTime(ms)
<img class="stretch" data-src="content/operators/throttleTime.png">
</section>
<section>
.debounceTime(ms)
<img class="stretch" data-src="content/operators/debounce.png">
</section>
<section>
.switchMap(function => { return Observable to switch })
<img class="stretch" data-src="content/operators/switchmap.png">
</section>
<section>
Error Handling
</section>
<section>
.retry(number)
<img class="stretch" data-src="content/operators/retry.png">
</section>
<section>
.catch(return new Observer)
<img class="stretch" data-src="content/operators/catch.png">
</section>
</section>
<!-- <section>
Overloaded
<img class="stretch" data-src="content/overload.gif">
</section> -->
<section>
Creating a timer using observables that executes each second, for 5 seconds
<pre class="fragment"><code class="TypeScript" data-trim contenteditable>
let observable = Observable.interval(1000);
let subscription = observable
.take(5)
.subscribe(next => {
console.log(next)
});
</code></pre>
</section>
<!-- <section>
Polling a backend service each 5 seconds
<pre class="fragment"><code class="TypeScript" data-trim contenteditable>
const myObservable = new Observable(observer => {
Observable.interval(5000).subscribe(next => {
this._http.get("www.ulv.no").subscribe(value => {
observer.next(value);
})
});
});
myObservable
.subscribe(value => {
console.log(value);
})
</code></pre>
</section> -->
<section>
Polling an unstable backend that crashes all the time
<pre class="fragment"><code class="TypeScript" data-trim contenteditable>
Observable.interval(5000)
.switchMap(() => {
return this._http.get("www.ulv.no")
.catch(error => Observable.empty())
})
.subscribe(data => {
console.log(data);
})
</code></pre>
</section>
<section>
Only execute some code after no mouse movement for 1 second
<pre class="fragment"><code class="TypeScript" data-trim contenteditable>
Observable.fromEvent(window, 'mousemove')
.debounceTime(1000)
.subscribe(next => {
console.log("No movment for one sec!")
});
</code></pre>
</section>
<section>
Subject (Active observables)<br />
<span class="fragment">
Shared by default
</span>
</section>
<section>
Observable with next inside
<pre><code class="TypeScript" data-trim contenteditable>
var myObservable = new Observable(observer => {
observer.next(42);
});
</code></pre>
</section>
<section>
Subject
<pre><code class="TypeScript" data-trim contenteditable>
let mySubject = new Subject();
mySubject.subscribe(next => {
console.log(next)
});
mySubject.next(42);
setTimeout(() => {
mySubject.next(500);
}, 1000);
</code></pre>
<p class="fragment">
Works really similar to EventEmitter
</p>
</section>
<section>
Skipping rest on Subjects and subtypes like Behaviour Subject
</section>
<section>
<section>
RxJS 5.6
</section>
<section>
Few functional changes
</section>
<section>
Can Use of() directly
<pre><code class="TypeScript" data-trim contenteditable>
Import { of } from 'rxjs'
of(😏, 😊, 😋)
</code></pre>
</section>
<section>
Can start to pipe
<pre class="fragment"><code class="TypeScript" data-trim contenteditable>
of(😏, 😊, 😋)
.map(.....)
</code></pre>
<pre class="fragment"><code class="TypeScript" data-trim contenteditable>
of(😏, 😊, 😋)
.pipe(
.map(.....)
)
</code></pre>
</section>
<section>
Why piping?
<p class="fragment">
Having global operators is bad
</p>
<p class="fragment">
Can treeshake
</p>
<p class="fragment">
Linters can be more helpfull
</p>
<p class="fragment">
Can easily create custom operators
</p>
</section>
</section>
<section>
<section>
🎉 RxJS 6.0 🎉
</section>
<section>
Smaller, faster, and easier to use
</section>
<section>
Simplified imports
<pre class="fragment"><code class="TypeScript" data-trim contenteditable>
import 'rxjs/add/operator/map';
import 'rxjs/add/observable/of';
</code></pre>
<pre class="fragment"><code class="TypeScript" data-trim contenteditable>
import { map, filter } from 'rxjs/operators';
import { of } from 'rxjs';
</code></pre>
</section>
<section>
Hundreds of import sites reduced to 'rxjs' and 'rxjs/operators'
<p class="fragment">
And a 3 more that's rarely used
</p>
<p class="fragment">
Like: rxjs/testing, rxjs/webSocet and rxjs/ajax
</p>
</section>
<section>
Will make rxjs easier to learn, use and run
</section>
<section>
New operator!
<pre class="fragment"><code class="TypeScript" data-trim contenteditable>
.throwIfEmpty(
() => new Error('No data passed to this operator')
)
</code></pre>
</section>
<section>
Renamed operators
<p class="fragment">
catch() => catchError()
</p>
<p class="fragment">
do() => tap()
</p>
<p class="fragment">
finally() => finalize()
</p>
<p class="fragment">
switch() => switchAll()
</p>
</section>
<section>
Renamed Observable-creation methods
<p class="fragment">
throw() => throwError()
</p>
<p class="fragment">
fromPromise() => from()
</p>
</section>
<section>
Deprecations!
</section>
<section>
Operator version of combineLatest, merge, zip and a few similar combiners
<p class="fragment">
Have to use them staticly now, like combineLatest(stream1, stream2)
</p>
</section>
<section>
Arrrghh! Breaking changes!
</section>
<section>
Use rx-jscompat and tslint fixer
<pre class="pragment"><code class="TypeScript" data-trim contenteditable>
npm install -g rxjs-tslint
rxjs-5-to-6-migrate -p src/tsconfig.app.json
</code></pre>
</section>
<section>
https://www.academind.com/learn/javascript/rxjs-6-what-changed/<br>
<iframe style="width: 700px; height: 650px;" src="https://www.academind.com/learn/javascript/rxjs-6-what-changed"></iframe>
</section>
</section>
<section>
<section>
😨 RxJS 7.0 😨
</section>
<section>
In development
</section>
<section>
Close to no changes, except blazingly fast and insanely tiny
</section>
<section>
Deprecations from 6 will be removed
</section>
</section>
<section>
<h2>
Reactive Extentions
</h2>
RxJS<br />
<p class="fragment">
<img class="stretch" data-src="content/wow.gif">
</p>
</section>
<!-- <section>
<section>
<h2>Do not overuse RxJS</h2>
</section>
<section>
Only where it providesas a benefit, and for the most part limited to async code execution
</section>
</section> -->
<section>
Jan Greger Hemb <br />
www.github.com/JGH153<br />
<a href="http://reactivex.io/" target="_blank">reactivex.io</a><br />
<a href="http://reactivex.io/rxjs/" target="_blank">reactivex.io/rxjs</a>
</section>
<section>
Questions?
<img class="stretch" data-src="content/questions.gif">
</section>
<section>
This page is intentionally left blank
</section>
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