Thinking Reactive in Javascript - WebRebels 2018

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Thinking Reactive in @ivanjov96

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Why I created this talk?

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Reactive programming!

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People didn’t see the point of the article!

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Ivan Jovanovic Senior software engineer @ nearForm https://ivanjov.com @ivanjov96

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What is Reactive programming?

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–André Staltz “Reactive programming is programming with asynchronous data streams.”

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What is Data Stream?

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“Data stream is an endless sequence of digital signals (data packets)”

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Data stream 10 20 30 40 50 60

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In JavaScript, Reactive programming is abstraction of all async processes into the data streams

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buffer(clickStream.throttle(500ms))

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map(‘get size of the buffer’) 1 2 3

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ﬁlter(number >= 2) 2 3 1 2 3

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Why do I need this reactive thing?

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• External service calls • Better performance • Highly testable • Abstraction over all async processes • Predictable code • Extendable code

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Observable Observable is ofﬁcial terminology for the stream

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Observer Observer subscribes to an observable and reacts to whatever item or sequence of items the observable emits.

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Reactive programming in JS • RxJS - the most popular, the biggest • MostJS - the best performance • Bacon.js • XStream - the smallest

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• Data ﬂow • Side effects • Functional programming React cons

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–Cycle.js ofﬁcial website “A functional and reactive JavaScript framework for predictable code”

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• Data ﬂow • Side effects • Functional programming Cycle.js pros

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Features • Functional (just write pure functions) • Reactive • Testable • Composable • Explicit dataﬂow • Made for large codebases

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Image taken from cycle.js.org

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run(app, drivers)

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Drivers - side effects • HTTP • DOM • WebSockets • Local storage driver • HTML5 Notiﬁcations driver • …

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Cycle.js ofﬁcial packages • DOM - collection of drivers that work with DOM; it has DOM driver and HTML driver, based on snabdom virtual DOM library • History - driver for History API • HTTP - driver for HTTP requests, based on superagent • Isolate - function for making scoped dataﬂow components • Run - `run` function for apps made with `xstream` • Most-run - `run` function for apps made with `most` • RxJS-run - `run` function for apps made with `rxjs`

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Model-View-Intent

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Simple counter app

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Intent

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Model

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View

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View + CSS

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Handling HTTP requests

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Working with components

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Cycle.js Cons • Community • Learning new paradigm • Some apps don’t need to be reactive

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Conclusion • Old paradigm with the new usage • Not for everyone • Perfect for real time apps that require high performance • Testable, predictable code • One interface for all async processes