What The Flux? A Quick Primer on React & Flux Peter Piekarczyk June 10, 2015 

UI Engineer Trunk Club @peterpme github.com/ppiekarczyk 

Getting Started 

What Is React Not? • Not a framework like Angular or Backbone • Not a templating engine • Not a framework replacement 

What Is React? • A library for creating UI • Data flows in, virtual DOM comes out • Diff the next virtual DOM with the current one • When the data changes, re-render! • Render only what I need 

Past & Present Brunch With Panache A modular approach to building web apps with Brunch github.com/trunkclub/brunch-with-panache speakerdeck.com/jhabdas/brunch-with-panache • Backbone • Chaplin • JQuery • Brunch • Coffeescript • Automatic memory management • Controllers & composition • Rails-like routes in custom router • Consistent CLI interface • CommonJS + Amd Support 

SOA BWP BWP 

BWP BWP BWP BWP BWP 

“Ugh, guys?” Everything worked great for a long time Until it stopped working that great.. • Numerous API calls & hydrations • Lot of useless re-rendering • Increased load times • Huge flame chart spikes • User complaints • Dedicating way too much time 
 for render debugging & optimization • Patches weren’t doing the trick What could UI solve on its own? 

React to the Rescue! • Reusable, encapsulated components • Single responsibility • Makes no assumptions about your current stack • Efficient diff’ing algorithm re-renders only what it needs to • Declarative style makes it easier to focus on the app itself • Less mental overhead of bringing in templates & views together For the first time, our backend’s were much more comfortable with our code 

React to the Rescue! Why is React a big deal? • State is hard • UI is a lot of state • Debugging is a pain • Open sourced for over 3 years • Easy to integrate into any project • Used by Facebook, Instagram, Firefox Devtools, Hipchat, Squarespace • Everyone wants to be React React Solves Your Problems. All of them. 

React to the Rescue! Templates & Views Our code became much more manageable 

React to the Rescue! CSS Styles as Components Our design & code became much more manageable 

Passing Down Data What are Props? Properties that are received from above and are immutable
 as far as the component is concerned 

Passing Down Data What is State? The state starts with a default value when a Component mounts and then suffers from mutations in time (mostly generated from user events). 

Passing Down Data 

Now What? 

Flux • Pattern, not a framework • Data layer • Uni directional data flow • Actions - facilitate data • Stores - application state & logic • Dispatcher - traffic control 

Uni Directional Flow STORE COMPONENT Model View 

Flux STORE COMPONENT `CHANGE` event user interaction ACTION
 CREATOR `CREATE` action DISPATCHER STORE callback 

Component Sign up modal 

Component Click Handler 

Action Creator 

Dispatcher 

Store 

Store 

Component 

Flux Keeps Things Predictable 

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Today React with (Re)Flux Build all the things • React • Reflux • Babel • Webpack • npm • Idea of components • A flavor of Flux • ES6 to 5 transpiler • Module Bundler • No more bower! 

Thank you