Rx.Observable.prototype.multicast(subject | subjectSelector, [selector])

Multicasts the source sequence notifications through an instantiated subject into all uses of the sequence within a selector function. Each subscription to the resulting sequence causes a separate multicast invocation, exposing the sequence resulting from the selector function's invocation. For specializations with fixed subject types, see publish, share, publishValue, shareValue, publishLast, replay, and shareReplay.


  1. subjectSelector (Function): Factory function to create an intermediate subject through which the source sequence's elements will be multicast to the selector function.
  2. subject (Subject): Subject to push source elements into.
  3. [selector] (Function): Optional selector function which can use the multicasted source sequence subject to the policies enforced by the created subject. Specified only if subjectSelector is provided.


(Observable): An observable sequence that contains the elements of a sequence produced by multicasting the source sequence within a selector function.