React is 100% framework. They even bring their own DSL. It's absurd to call React library.
Library is something that can be pulled off project and replaced with something else. There's no non-trivial project where replacing React with anything would be possible. Every React web app is built around React.
I think absurd is a bit strong. It'd be absurd to call something like rails a library.
I think you can probably see that distinction already, but to spell it out React is described as a library precisely because it does just one thing - the view - and leaves it to you to figure out the entirety of the rest of the stack / structure of your app.
Framework, at least to me, but I also believe commonly, means something that lets you build a full application end to end using it.
You can't do that with React unless your app is just something that lives in the browser either in-memory or with some localstorage backing or something. If that's your app, then probably I'd agree React is your framework per se, but that's hardly ever the case.
By the way, back to my original point, I still do think these things are impossible to define and in lots of ways these terms don't matter - if it's a framework for you, it's a framework - but I just had to defend my position since you described it as absurd :-)
100% this. To this day the official website still describe itself as a library, and I'm convinced it's completely for marketing reasons, since 'framework' feels heavy and bloated, like Angular or Java Spring, while 'library' feels fast and lightweight, putting you in control.
Framework can be more or less modular, Angular or Ember choose to be 'battery included', while React choose to be more modular, which is simply choosing the other end of the spectrum on the convenience-versus-flexibility tradeoff.
React ostensibly only care about rendering, but in a way that force you to structure your whole data flow and routing according to its rules (lifecycle events or the 'rules of hooks', avoiding mutating data structures); No matter what they say on the official website, that's 100% framework territory.
Lodash or Moment.js, those are actual bona fide libraries, and nobody ever asked whether to use Vue, Angular or Moment.js, or what version of moment-js-router they should use.