Looking for documentation on RxJS is sometimes a bit of a hassle
What is Reactive Extensions?
Reactive Extensions (or officially called ReactiveX) is a library for composing asynchronous and event-based programs by using observable sequences. [Source]
In other words, it is a way to look at events and asynchronous operations as if they were a stream or collection of data. This has the added benefit of being able to easily select parts from that data, filter the interesting events,...
What is RxJS?
Looking for documentation?
If you search around for documentation, please pay attention to the url that you're looking at! You've got RxJS 4 documentation as well as RxJS 5 documentation. And the problem is that both of them are located on the same domain!
Looking for RxJS 5?
For RxJS 5, you need to head over to http://ReactiveX.io/RxJS. Strangely enough, you'll find the documentation on the same domain. This is the documentation that you're looking for if you're using RxJS in Angular for example! The website'll look similar like this:
For the github sources, you can find RxJS 4 here and RxJS 5 right here.