> PT-BR post: [https://goo.gl/RvrTez](https://goo.gl/RvrTez)

Last Saturday I was in Sao Paulo for the React Conf BR. I was very excited about this event, and I had been planning this travel for some months. That was going to be the first edition and actually, that was going to be the first time we had a React Conf in Latin America, so I believe I wasn’t the only one excited about that. So, I would like to share my main impressions about each talk and the conf itself.

### The magic world of tests with Jest

The conference was opened by [Fernando Daciuk](https://medium.com/@fdaciuk) talking about TDD and Jest. Daciuk is an experienced developer and his didactic is excellent. More than just showing what we are used to see about TDD, he talked about the importance of tests to document our code and our functionalities and he also guided us through a baby step test case using _Jest_. Here you can access the link for his presentation slides: [https://goo.gl/joaJbf](https://goo.gl/joaJbf)

![](https://pbs.twimg.com/media/DLyxQalWAAErX0i.jpg:large)

### Transforming a legacy frontend in a React Application

This talk was presented by [Kete Martins Rufino](https://medium.com/@ketemr) and [Christiano Milfont](https://medium.com/@cmilfont). They brought us some approaches they were using to migrate a Backbone application to React and Redux. They shared the difficulties they had in the process and how they solved them. This talk was really interesting, because it made clear that we don’t need to be attached to an specific technology just because we have a legacy application. There are sometimes where you don’t find a made solution and you end up creating your own, but there are always ways to keep evolving the projects. Their presentation’s slides can be found here: [goo.gl/6g3bFc](https://t.co/J6gId718yC "https://goo.gl/6g3bFc")

![](https://pbs.twimg.com/media/DLiZ8hrX0AA6ToA.jpg:large)

We are here now at @ReactConfBR! Let’s esteem the brazilian conferences! May we have more events of this level.

### Let’s dive into Babel: How everything works

[Marcelo Camargo](https://medium.com/@haskellcamargo) is the creator of [_Quack lang_](https://github.com/haskellcamargo/quack) and he has a comprehensive knowledge about compilers and functional programming. He introduced us to Babel’s internals and how Babel handles the JSX parsing. He also showed how we could use Babel plugins to create custom functionalities to a programming language.

![](https://pbs.twimg.com/media/DLy1oTiWsAAbFSx.jpg:large)

**Be aware:** One of the slides contains a prank, so, better you turn your **sound off** before going trough them. The presentation slides can be found here: [https://goo.gl/7rvKTG](https://goo.gl/7rvKTG)

### Statically Typing your GraphQL App

[James Baxley](https://medium.com/@jbaxleyiii), one of the core developers from _Apollo_ and _MeteorJS,_ gave an amazing talk about how we could add type checking for GraphQL queries in React Apps. He also wrote an article about this topic which you can find here: [https://goo.gl/TN8Tn2](https://goo.gl/TN8Tn2)

The link for his presentation slides: [https://goo.gl/6TouPh](https://goo.gl/6TouPh)

![](https://pbs.twimg.com/media/DLy24v3WkAEd2yD.jpg:large)

### Scratching React Fiber

[Raphael Amorim](https://medium.com/@raphamorim) is an active open source contributor and a jQuery foundation’s member. He talked about the React’s new version and how the rewritten of the render algorithm impacts on browser’s animation performance. The link for his presentations’s slides can be found here: [https://goo.gl/133WYP](https://goo.gl/133WYP)

![](https://pbs.twimg.com/media/DLy3lVsWkAEYQEz.jpg:large)

Those were all the presentations for the morning. Right after them, we had a Fishbowl time, where some people stay sit in chairs on the stage, asking question to others. Anyone who wants to ask some question, or answer, could go to the stage an take a chair. The main rule was: One of the chair should be always empty, to give space to others.

![](https://pbs.twimg.com/media/DLiu66EUEAUyHNC.jpg:large)

### MobX: The light side of the force

Back from lunch, the first talk was given by [Clara Battesini](https://medium.com/@clarabatt). She is a Frontend developer and a Computer Engineering student. She introduced us to [_MobX_](https://github.com/mobxjs/mobx), a state manager that can be an alternative to Redux. Here is the link for her presentation slides: [https://goo.gl/qEiZ9W](https://goo.gl/qEiZ9W)

![](https://pbs.twimg.com/media/DLzA0IrWkAAb8aU.jpg:large)

### Show do Milhão React PWA - Success case

In this talk, João Gonçalves presented a case of success of the web app “Show do milhão”. He showed us how he built a progressive web app, that also uses React and Redux. The link for his presentation slides: [https://goo.gl/jQckxZ](https://goo.gl/jQckxZ)

![](https://pbs.twimg.com/media/DLzCvfLX0AEsk1r.jpg:large)

### Building the Pipefy mobile app in 3 weeks with React Native, GraphQL and Apollo

[Raphael Costa](https://medium.com/@raphaelwcosta), full stack developer at [Pipefy](https://www.pipefy.com/), talked about how he built an entire app in only three weeks, using React Native and GraphQL with the Apollo stack. Presentation slides can be found here: [https://goo.gl/9UZG1z](https://goo.gl/9UZG1z)

![](https://pbs.twimg.com/media/DLzDky9X0AE9fNA.jpg:large)

### The GraphQL and Apollo stack: connecting everything together

[Sashko Stubailo](https://medium.com/@stubailo) talked about Apollo ecosystem. How all its amazing tools can be combined to help us build complex applications in a simple way. He also shared a little about Apollo future and their goals. The slides for his talk can be found here: [https://goo.gl/87yUNG](https://goo.gl/87yUNG)

![](https://pbs.twimg.com/media/DLzG4imX0AAf7yv.jpg:large)

### Why React is good for business

On this talk, [Sebastian Ferrari](https://medium.com/@sebas5384), CTO and Co-Founder at Taller, gave great opinions about why React is also good for business point of view. How its functional programming premises help to increase predictability and decrease bugs in the applications, and how these things affect the application life cycle, the developers and the users.

The presentation slides in PT-BR: [http://bit.ly/2xuP8Pm](https://t.co/u5zwfZnThF "http://bit.ly/2xuP8Pm")

![](https://pbs.twimg.com/media/DLzJNt7WkAAH9ua.jpg:large)

### Gorgeous Apps with React Motion and Animations

On his presentation, [Henrique Sosa](https://medium.com/@henriquesosa) showed the different approaches we have, to handle animations in React applications. Then, he introduced us to [React Motion](https://github.com/chenglou/react-motion) and talked about its cons and pros. Link for the presentation’s slides: [https://goo.gl/CNDthc](https://goo.gl/CNDthc)

![](https://pbs.twimg.com/media/DLzbvPgXkAQFzs8.jpg:large)

### Isomorphic React + Redux App

React supports server side rendering, that doesn’t mean that everything works out of the box though. [Matheus Marsiglio](https://medium.com/@mtmr0x) talked about the difficulties he faced developing an isomorphic application, such as keep the state synced between server and browser. Then he showed some approaches he followed to solve them. Link for presentation slides: [https://goo.gl/U4FvcY](https://goo.gl/U4FvcY)

![](https://pbs.twimg.com/media/DLzJzGmX4AsEDwo.jpg:large)

### What React has about Functional

In this amazing presentation, [Matheus Lima](https://medium.com/@matheusml) talked about how functional programming influenced on React’s development, through pure functions, immutability and composition, and how we could use more those concepts to write declarative code and simplify our component logics. The slides for this presentation are in PT-BR and can be found here: [https://goo.gl/qfFD4G](https://goo.gl/qfFD4G)

![](https://pbs.twimg.com/media/DLzLmAdX4AMcdW9.jpg:large)

### React Performance from Scratch

[Keulelr Magalhaes](https://medium.com/@keuller), Software Engineer at PagSeguro, talked about performance measurement and showed us how he did some benchmarks, comparing _React_, [_InfernoJS_](https://github.com/infernojs/inferno) and [_Preact_](https://github.com/developit/preact)_._

Link for the presentation slides_:_ [https://goo.gl/prj3b1](https://goo.gl/prj3b1)

![](https://pbs.twimg.com/media/DLzLxm8XUAAwBq6.jpg:large)

### Continuos Integration / Continuos Deployment

[Geisy Domiciano](https://medium.com/@gdomiciano) is Frontend Developer at Polishop and also a Dog’s mom. On this great presentation, she talked about the importance of continuous integration and continuous deploy. How we could implant that in an application and which tools we could use to facilitate that.

Presentation slides can be found here: [https://goo.gl/LPTA6X](https://goo.gl/LPTA6X)

![](https://pbs.twimg.com/media/DLzMNtxWkAI6p60.jpg:large)

### Relay Modern

And the last talk from the day was given by [Sibelius Seraphini](https://medium.com/@sibelius) , Technical Lead at Entria and also one of the most active members in the React community in Brazil. He talked about Relay modern, the new features and the differences between the new and the old version. Presentations slides can be found here: [https://goo.gl/1yh1YD](https://goo.gl/1yh1YD)

![](https://pbs.twimg.com/media/DLzNKgiWkAAZhFM.jpg:large)

Notice that GraphQL was the buzzword during the conference. All the cases of success made me feel motivated to invest some time on it.

I almost forgot to mention, everyone won a cardboard VR glasses kit, which was so cool.

![](https://pbs.twimg.com/media/DLzPk5SXkAAE8GY.jpg:large)

To close the day, the english school [An English Thing](http://www.anenglishthing.com.br/) sponsored an afterparty with free drinks.

![](https://pbs.twimg.com/media/DLzO3FuX0AEFuI4.jpg:large)

The event was really great and connected a lot of people. Congrats for all the speakers to been share their knowledge and specially the organizers to show that we have an awesome React community here in Brazil.

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