Subscription Class

Subscriptions

• Calling Observable#subscribe() returns a Subscription
• A Subscription lets you listen to next, error, and complete notifications from an observable
• The Subscription object also enables you to unsubscribe from an observable

Creating a Subscription

We've already seen how to subscribe to an Observable:

source$.subscribe({
  next: (value) => console.log(value),
  error: (err) => console.error(err),
  complete: () => console.log('Complete!'),
});

You can also subscribe without an object by using positional parameters:

source$.subscribe(
  (value) => console.log(value),
  (err) => console.error(err),
  () => console.log('Complete!')
);

Joining Subscriptions

Calling subscribe returns a Subscription object:

const subscription = source$.subscribe();

You can add additional subscriptions to the same subscription object:

const subscription = first$.subscribe();

subscription.add(second$.subscribe());

This can be useful for managing the subscription lifecycle of multiple observables

Subscription Class

You can create a Subscription object on your own by newing up the Subscription class:

const subscription = new Subscription();

subscription.add(source$.subscribe());