kefir/src/interop/from-es-observable.js

Reactive Programming library for JavaScript inspired by Bacon.js and RxJS with focus on high performance and low memory usage

import stream from '../primary/stream'
import $$observable from './symbol'

export default function fromESObservable(_observable) {
  const observable = _observable[$$observable] ? _observable[$$observable]() : _observable
  return stream(function(emitter) {
    const unsub = observable.subscribe({
      error(error) {
        emitter.error(error)
        emitter.end()
      },
      next(value) {
        emitter.emit(value)
      },
      complete() {
        emitter.end()
      },
    })

    if (unsub.unsubscribe) {
      return function() {
        unsub.unsubscribe()
      }
    } else {
      return unsub
    }
  }).setName('fromESObservable')
}