Quite alright—I'm usually very precise on these matters as well. Nonetheless I disagree with the point. My opinion after actually having used React.js is that

Quite alright—I'm usually very precise on these matters as well. Nonetheless I disagree with the point. My opinion after actually having used React.js is that it is more than a UI library. I've used other UI libraries and React.js is more "comprehensive." I do grant, however, that React.js alone will not suit most needs. You will generally want to add a few other pieces. In my case I also used refluxjs and react-router. I also used store.js as an abstraction for browser storage.