[RxJS] RefCount: automatically starting and stopping an execution

With the connect() method on a ConnectableObservable, the programmer is responsible for avoiding leaked executions of shared RxJS Observables. This lesson will teach you about refCount(), a handy operator that creates an automatically connected Observable, to avoid manually using connect().

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

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 subA = shared.subscribe(observerA); // start

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 = shared.subscribe(observerB); // 1 => 2
}, 2000);

setTimeout(function () {
  subA.unsubscribe(); // 2 => 1
  console.log('unsubscribed A');
}, 5000);

setTimeout(function () {
  subB.unsubscribe(); // 1 => 0 (stop)
  console.log('unsubscribed B');
}, 7000);


/*
"source 0"
"A next 0"
"source 1"
"A next 1"
"source 2"
"A next 2"
"B next 2"
"source 3"
"A next 3"
"B next 3"
"source 4"
"A next 4"
"B next 4"
"unsubscribed A"
"source 5"
"B next 5"
"source 6"
"B next 6"
"unsubscribed B"
*/