RxJS has several key features that make it a powerful tool for handling asynchronous data streams in JavaScript: 1. Observables: RxJS is built around the concept of Observables, which represent asynchronous data streams. Observables can be transformed, combined, and consumed in a declarative way using operators. 2. Operators: RxJS provides a wide range of operators that can be used to transform and manipulate Observables. These operators include `map`, `filter`, `reduce`, `scan`, `merge`, `concat`, `switchMap`, and many others. 3. Error handling: RxJS provides operators for handling errors in Observables, such as `catchError` and `retry`. 4. Schedulers: RxJS provides schedulers for controlling the timing and execution context of Observables. Schedulers can be used to control the concurrency of Observables, to delay or throttle emissions, and to run Observables on different threads or processes. 5. Backpressure handling: RxJS provides backpressure handling mechanisms for dealing with Observables that produce data faster than it can be consumed. These mechanisms include `buffer`, `throttle`, `debounce`, and others. 6. Interoperability: RxJS can be used with other libraries and frameworks, such as Angular, React, and Node.js. RxJS also supports integration with other reactive programming libraries and platforms, such as ReactiveX and RxJava. 7. Testability: RxJS provides testing utilities for creating and manipulating Observables in unit tests. This makes it easier to test asynchronous code and ensure that Observables emit the expected values.