Reactive Programming with RxJS 5

Creating Observables

There are several ways to create Observables, the create operator being the most obvious one. The create operator in the Rx.Observable object takes a callback that accepts an Observer as a parameter. That function defines how the Observable will emit values. Here’s how we create a simple Observable:

const observable = Observable.create(observer => {
  observer.next("Simon");
  observer.next("Jen");
  observer.next("Sergi");
  observer.complete(); // We are done
});

When we subscribe to this Observable, it emits three strings by calling the next method on its listeners. It then calls complete to signal that the sequence is finished. But how exactly do we subscribe to an Observable? We use Observers.

The Observer ...