> For the complete documentation index, see [llms.txt](https://soufatn.gitbook.io/rxjs-book/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://soufatn.gitbook.io/rxjs-book/summary/observable/observable_instance_methods/multicast.md).

# multicast

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`.

## Arguments

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.

## Returns

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

## Example