Learn TypeScript 3 by Building Web Applications

RxJS basics − subscriptions

To register an observer with Observable, you have to call its .subscribe(...​) method and pass your observer as an argument. In return, you'll get a Subscription object, which you can use to cancel the subscription once you are not interested anymore:

import { of } from 'rxjs'; 
 
const myObservable = of(1,3,3,7); 
const mySubscription = myObservable.subscribe(x => console.log(x)); 
... 
mySubscription.unsubscribe(); 

As you might have noticed in this example, you are not forced to define all the contract methods (that is, next, error, and complete). However, just like the promises, it is best to handle at least the error case!

When you subscribe to Observable, you actually create an execution of it. This is an important ...