@reactivex/rxjs/doc/subscription.md

Reactive Extensions for modern JavaScript

# Subscription

**What is a Subscription?** A Subscription is an object that represents a disposable resource, usually the execution of an Observable. A Subscription has one important method, `unsubscribe`, that takes no argument and just disposes the resource held by the subscription. In previous versions of RxJS, Subscription was called "Disposable".

```js
var observable = Rx.Observable.interval(1000);
var subscription = observable.subscribe(x => console.log(x));
// Later:
// This cancels the ongoing Observable execution which
// was started by calling subscribe with an Observer.
subscription.unsubscribe(); 
```

<span class="informal">A Subscription essentially just has an `unsubscribe()` function to release resources or cancel Observable executions.</span>

Subscriptions can also be put together, so that a call to an `unsubscribe()` of one Subscription may unsubscribe multiple Subscriptions. You can do this by "adding" one subscription into another:

```js
var observable1 = Rx.Observable.interval(400);
var observable2 = Rx.Observable.interval(300);

var subscription = observable1.subscribe(x => console.log('first: ' + x));
var childSubscription = observable2.subscribe(x => console.log('second: ' + x));

subscription.add(childSubscription);

setTimeout(() => {
  // Unsubscribes BOTH subscription and childSubscription
  subscription.unsubscribe();
}, 1000);
```

When executed, we see in the console:
```none
second: 0
first: 0
second: 1
first: 1
second: 2
```

Subscriptions also have a `remove(otherSubscription)` method, in order to undo the addition of a child Subscription.