It's a framework specific DSL anyway. (Unlike e4x, which is actually a standardized feature). There isn't a spec decides how it must be interpreted. And it also

It's a framework specific DSL anyway. (Unlike e4x, which is actually a standardized feature). There isn't a spec decides how it must be interpreted. And it also don't matter as long as the specific framework that use jsx output standard javascript that browser can understand. In practice, every framework interpret jsx in slightly different way. React has own. Vue has own. Solid has own. And even react itself interpret JSX in 2 way (the new and old jsx compiler). So I feel there really isn't a rule that you can't compile jsx in some specific way because the output is never part of the specification of jsx from the beginning.