Are you aware of the Links programming language / research project? It lets you write code in a uniform syntax that compiles down to a mixture of Javascript, server-side code, and SQL - all from the same source file, if you like. Client- and server-side Links code can call each other seamlessly; and it has a syntax for inline HTML fragments is strikingly similar to, and I suspect influenced, JSX.

Not quite the same thing as you describe, but it's exploring a similar part of the design space:

http://links-lang.org/