Is RxJS a TypeScript?

I would say yes . Especially if you are thinking of learning Angular. because Angular heavily use RXJS component, specially Observables. It is worth notice that so far Observable are the best way of handling asynchronous data in javascript.

It’s an interesting fact to know that the RxJS project is using TypeScript actively and it helped to find bugs when the library was migrating from JavaScript.10 Ara 2020

RxJS (Reactive Extensions for JavaScript) is a library for reactive programming using observables that makes it easier to compose asynchronous or callback-based code .