The important thing with this technique is you can render before any JS has been downloaded, parsed and executed, which is a huge amount of time relative to HTML parse and paint.
fwiw, React isn't tied to Node: I've used it with Django via PyExecJS (which just uses raw JavaScriptCore).
I started with this line:
>initial rendering should definitely be on the server
this technique is called pre-rendering, and yes, I am amazed people don't do it.
"PyExecJS (which just uses raw JavaScriptCore)."
this seems pretty slow or can you cache the execution function. (aka you don't have to parse the js multiple times)
Our backend is jvm so we decided on closure, with this on startup we compile our templates on the server and then pass the rendering functions around pumping the data into it to render initial pages.
At the same time, we compile the same templates into javascript functions which are included into our app via the closure dependency system to render on the client.
This has the advantage of not having to parse and "compile" a template at the point of delivery.
This is why I think react is an excellent library, because it allows anybody to do this and brings this notion into the minds of developers who jump easily on bandwagons.
I also think that the react team are well on their way to building a library which would fair excellently under all sorts of static analysis
Our approach is going to make js interop performant with our stack (which is not jvm). We don't have a concrete plan at this time. You would need more than jsx to make this work through (jsx is just sugar)
fwiw, React isn't tied to Node: I've used it with Django via PyExecJS (which just uses raw JavaScriptCore).