@basic-streams/multicast

multicast<T>(stream: Stream<T>): Stream<T>

Creates a stream with the same events as the given stream. The new stream will have at most one subscription at any given time to the original stream. This allows you to connect several consumers to a stream.

Each consumer only gets events produced after it was added.

import multicast from "@basic-streams/multicast"

let cb

const stream = _cb => {
  console.log("start")
  cb = _cb
  return () => {
    console.log("stop")
  }
}

const result = multicast(stream)

const unsubscribe1 = result(x => {
  console.log("consumer 1", x)
})

// > "start"

const unsubscribe2 = result(x => {
  console.log("consumer 2", x)
})

// No output this time, because we reuse the previous connection,
// and don't call `stream()` again.

cb(1)

// > "consumer 1" 1
// > "consumer 2" 1

unsubscribe1()

// No output. The connection is still active because
// one consumer is still subscribed.

unsubscribe2()

// > "stop"