Robert Zaremba Blog

Notes: ReactiveConf 2016

The ReactiveConf 2016 is a great venue where you meet and hear from the new technology drivers, early adapters and it innovators. It had place in the organizers home town - Bratislava, which is another reason to attend the conference - to visit a charming part of the west Europe.

Despite the name, the conference wasn’t much about React

Note: The cover letter of the majority of presentation was This library is awesome, but in alpha stage, so use it under your own responsibility


Jest - a new power-horse for testing. Currently I’m using Phantomjs + Mocha + Chai + Sinon for unit and module testing. Casper.js comes to do the functional tests. It works very well, you can get a basic impression about this bundle at Quick Start Guide. Since my stack is already based on Facebook solutions, Jest - Painless JavaScript Testing is a fair update to our stack. It’s well integrated, fast and parallelized. It’s definitely the next step for the testing stack I would like to upgrade. You may ask - what does it solve? Well - currently only speed. But for long term plan - it solves:

  • The upgrade pains - Jest integrates test running, assertions and mocking (so we will rely only one library instead of 3: Mocha, Chai and Sinon)
  • Expect better integration with Facebook frameworks.
  • Integrates seamlessly with Babel and with TypeScript (ts-jest) and Flow (Babel-jest).
  • Immersive Watch Mode - you have to watch it

Still not convinced? Watch Test JavaScript with Jest.


Cypress is another testing framework which integrates the testing process. It’s another great update for the standard testing setups, which brings awesome debugging + reporting. Though I’m sold for Jest.

Reason ML

Have you heard about Elm? Now it’s time for Reason.

Reason is a new interface to OCaml - a highly expressive dialect of the ML language featuring type inference and static type checking. Reason provides a new syntax and toolchain for editing, building, and sharing code, and will evolve in the open as a community collaboration.


Wonder how to speed up React rendering, or create JS-less applications?

Next.js is a minimalistic framework for server-rendered React applications.

State in React

During last year many solutions emerged from the missing strong default state management Flux implementation. Market seams a strong adoption for redux. However the evolution hasn’t finished. We have new strong player - MobX. Currently I’m using our own custom router. I was planning to integrate Redux, however MobX took my attention and the presentation was great. MobX is well designed library based on Observables. It’s batter tested and it seams to have strong market adoption. Bonus: mobx-router - as well integrated solution for routing in React!

Other interesting libraries



GraphQL takes traction. I had a pleasure taking with developers implementing and using GraphQL.


Have you ever thought about bringing declarative data manipulation into the application? Immutable distributed general-purpose database? Does it make sens? If you have this questions then have a look at Datomic.