[RxJS] Stopping a shared observable execution

ConnectableObservable has the connect() method to conveniently dictate the start of the shared execution of the source Observable. However, we need a mechanism to dictate the stop of the shared execution, otherwise a leak happens. This lesson will teach you how to do that, and it's all about Subscriptions.

 

var connectableObservable = Rx.Observable.interval(1000)
  .do(x => console.log('source ' + x))
  .multicast(new Rx.Subject());

var observerA = {
  next: function (x) { console.log('A next ' + x); },
  error: function (err) { console.log('A error ' + err); },
  complete: function () { console.log('A done'); },
};

var sub = connectableObservable.connect(); // start

var subA = connectableObservable.subscribe(observerA);

var observerB = {
  next: function (x) { console.log('B next ' + x); },
  error: function (err) { console.log('B error ' + err); },
  complete: function () { console.log('B done'); },
};

var subB;
setTimeout(function () {
  subB = connectableObservable.subscribe(observerB);
}, 2000);

setTimeout(function () {
  sub.unsubscribe(); // stop
  console.log('unsubscribed shared execution');
}, 5000);

 

Just remember that with connect we are manually controlling the start of the shared execution, and then we keep a subscription in order to manually control the stop of the shared execution. All of this is in order to avoid leaks.