All the design work was done by an actual designer who maintained the JSX directly. He knows enough javascript to get around but basically he just pretended it was HTML. JSX is awesome because it means designers can commit directly without involving engineering.
As a developer I'm interested enough to try React.js on my next project. However, it seems like designers will still need to write Javascript to implement repeating structures (tables, lists, etc.)? Just like designers don't want me fiddling with their HTML and CSS, I don't want them fiddling with my code -- but React.js's model seems to make such a separation of concerns impossible?
You can of course continue to have designers handoff markup/CSS for integration by engineering. But if your designer can handle basic javascript, you needn't involve engineering at all. In practice it doesn't really matter if the individual views are sloppy javascript since React separates concerns so well.
All the design work was done by an actual designer who maintained the JSX directly. He knows enough javascript to get around but basically he just pretended it was HTML. JSX is awesome because it means designers can commit directly without involving engineering.