What's the difference between publish and multicast operator in rxjs 5?

Question

I'm reading the rxjs manual, I'm a little confused about what's the difference between multicast and publish operators. They seem very similar.

Answer 1

I had the same question when reading http://reactivex.io/rxjs/manual/overview.html. So to make it clear, .publish() is just shorthand for .multicast(new Rx.Subject()) (and publishBehavior, publishLast, and publishReplay are similar but instantiate BehaviorSubject, AsyncSubject and ReplaySubject respectively).

Answer 2

They are indeed very similar, and they have a history that makes it even more confusing.

In simple terms, publish is a special case of multicast. publish always creates a new subject (and then pretty much uses multicast), whereas multicast uses the subject provided as an argument.