RxJS

A powerful reactive programming library for JavaScript that uses Observables to compose asynchronous and event-based programs.

RxJS treats asynchronous data streams (from user clicks and API responses to websockets) as collections you can query, filter, and project. By combining the Observer pattern with functional programming principles, it replaces nested callbacks and fragile state machines with clean, declarative pipelines. Developers use its extensive suite of over 100 operators (like switchMap, debounceTime, and catchError) to orchestrate complex async orchestrations with minimal boilerplate and robust error handling.

https://rxjs.dev