RxJS
RxJS (Reactive Extensions for JavaScript) is a library for reactive programming using Observables, to make it easier to compose asynchronous or callback-based code. It provides a powerful set of operators to transform, combine, and manage streams of data or events, enabling developers to handle complex asynchronous workflows in a declarative and functional style.
Developers should learn RxJS when building applications with complex asynchronous logic, such as real-time data streams, event handling, or state management, particularly in front-end frameworks like Angular which uses it extensively. It's valuable for scenarios like handling user interactions, API calls, WebSocket connections, or any situation where data changes over time, as it simplifies code by reducing callback hell and improving readability and maintainability.