rxjs

# RxJS

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RxJS is a library for composing asynchronous and event-based programs with
Observable values. This repository contains the platform-based next generation
of RxJS, planned for release as **RxJS 9**.

> RxJS 9 is prerelease work in development. The planned first beta is
> `9.0.0-beta.0`, but it has not been published to npm yet. The `next` tag still
> points to the earlier RxJS 8 prerelease, while RxJS 7 remains the production
> `latest` line and continues to be maintained.

## Why RxJS 9? What happened to RxJS 8?

RxJS 8 was real work, not a skipped release. Development began years ago and
was paused while the Web Platform Observable proposal was finalized. The new
implementation is a platform-based generation rather than a continuation of
that paused RxJS 8 branch, so it starts at version 9 to make the architectural
break unmistakable and avoid presenting the old RxJS 8 work as the released
product.

## What is different in RxJS 9?

- RxJS uses the native web-platform `Observable` when one exists and installs
  a conforming fallback only when needed.
- RxJS operators and factories are exact, module-owned Symbols. They do not add
  string-named RxJS methods to the platform API.
- Platform Observable behavior and producer-per-subscription behavior are
  explicit, separate contracts. Use `ColdObservable` when each direct
  subscription must create its own pr