Hey all, as Arkency we launched React.js koans 2 days ago. To our surprise it gathered over 1500 GitHub stars and it's now a trending repo - https://github.com/arkency/reactjs_koans
The original version uses ES6, but the main goal was to teach React.js not ES6 (not that much). Long story short - it would be great to put the Opal version as well. This may be a good promotion for Opal as React.js is nowe getting more and more popular. Someone already created an issue for that: arkency/reactjs_koans#22
Just a full disclosure here - this repository has a book ad in the README - thanks to the people buying the book, we can spend more time/money on doing open source like this. If this is not a problem, then your help in doing the Opal version would be more than welcome. Even just porting the first exercise would be of much value - as then it would be easier for others to jump in and help with the next exercises.