I don't think many have embraced the .jsx extension. And arguably it doesn't make a lot of sense, because when working with most modern frameworks/libs, JSX is

I don't think many have embraced the .jsx extension. And arguably it doesn't make a lot of sense, because when working with most modern frameworks/libs, JSX is not the only non-standard-js element in the file. Should we call it .es6, .es2015, .es2015+jsx ? So yeah, sticking with .js is common.