React Native is a JavaScript framework designed for building user interfaces, independent of traditional web technologies such as HTML and CSS. It emphasizes using JavaScript throughout, including for styles and layouts, with a strong focus on modern architectures and component-based design. The framework is in beta and evolving, with potential for dynamic app updates and cross-platform capabilities, but it still faces performance issues and has some community-driven elements.

1. React Native
introduction
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2. ● not a Hybrid App framework
● no HTML (DOM)
● no CSS (as we know it)
● no cross-platform app tool
● no, you cannot use jquery plugins with it
What RN is not
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3. A JAVASCRIPT LIBRARY
FOR BUILDING USER INTERFACES
What RN is
Atwood's Law: any application that can be written in JavaScript, will eventually be written in JavaScript.
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4. ● independent from:
○ data models
○ internal application logic
○ application state machine
○ design patterns for application architecture
● no two-way data-binding
● great for modern architectures (ex. DDD)
and frameworks (ex. Flux)
No application architecture binding
4

5. Components - fundamental building blocks
● components are state machines
● properties
● state
● internal logic
● render method
● JSX-based views
● style
● can be nested
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6. Component Example
6

7. Rethink established best practicesTM
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8. Everything* is javascript
● code is javascript
● styles are … javascript
● JSX is … javascript
● layout is … javascript
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9. Not your grand-father’s javascript
● use ‘strict’
● Javascript runtime: JavascriptCore/V8
● io.js platform (node rewritten)
● ES6 + some ES7 (draft):
http://facebook.github.io/react-native/docs/javascript-
environment.html#content
● Babel transpiler
● @flow - static code compilation
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10. JSX
var app = <Nav color="blue">
<Profile>click</Profile>
</Nav>
var Nav, Profile;
var app = React.createElement(
Nav,
{color:"blue"},
React.createElement(Profile, null, "click")
);
Always Uppercase Component Names
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11. Styles
● similar to CSS
● no class
● dash-separated => camelBack (mixedCase)
● subset of CSS only
● flexbox layout
● is done in Javascript
● can be easily and predictably combined
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12. Layout
● Flexbox + some css
● Implemented by facebook in … Javascript
https://github.com/facebook/css-layout
● Subset of web layout
● No baggage
● Side note - it transpiles to C and Java (!)
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13. Flexbox layout concepts
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14. Advantages of using JS everywhere*
● Simple management and coordination
● Get rid of CSS/HTML baggage
● Can be optimized better
● Your styles and views more dynamic
● easier reuse of styles
● everything for component in one place
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15. Application demo
15

16. Why react?
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17. States and Virtual View Hierarchy
Component
State
Your
code
Render
(in javascript)
View
Virtual View Hierarchy
Javascript objects
Image
Image
Text
React
Build native views
(native code)
17

18. State changes
Component
State: {}
Component
State: {workshops: {...} }
Update State
Reconciliation
Incremental changes
Animations
Javascript
Native code
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19. Incremental updates / animations
Update
Create
19

20. Some internals
20

21. Native/Javascript bridge
● Not in UI thread
● Asynchronous, serializable communication
● Batching requests
● Lots of optimisations already
● Potential optimisations in the future
● Flexible threading model
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22. Animations
● LayoutAnimations - simple
● Animated - fine grained control
○ Value animations still in javascript
○ But potential to optimise it and make native
○ Often declarative
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23. Animation example
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24. Extras
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25. Integration with ObjC/Swift
● Custom Access to APIs
http://facebook.github.io/react-native/docs/native-modules-ios.html#content
● Custom native UI components
http://facebook.github.io/react-native/docs/native-components-ios.html#content
● Direct Properties manipulation
http://facebook.github.io/react-native/docs/direct-manipulation.html#content
● RCTView can be embedded in native app
http://facebook.github.io/react-native/docs/embedded-app-ios.html#content
● Can work with cocoapods 25

26. Developer’s toolchain
● Very fast packager
● Verbose and helpful error diagnostic
● Live Reloads
● Element Inspections
● React Chrome extension
● Profiling
● Support for debugging via Chrome tools
● Modify code in debugger
● Tests (JS + Obj-C)
● IDEs: IntelliJ/WebStorm (Nuclide soon ?? )
● UIExplorer 26

27. Deployment options
27

28. Internal Architecture
28

29. Standalone app
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30. Development
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31. Debugging
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32. Remote server
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33. Live update - AppHub
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34. What Facebook wants to achieve?
What they tell
● Learn once - write anywhere
● No “cross-platform app framework”
● Less complex apps
What they don’t tell
● Common code shared as libs
● Dynamic app updates (A/B testing)
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35. Is it ready yet?
● Still beta and changing fast
● Still some (small) issues with performance
● Have not tested with really big application
● Some components are of beta quality
● Some components done by community
● Community is small but growing (Stack
Overflow)
● Documentation is heavily “distributed”
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36. Q&A
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