`createIteratorSubject` allows someone to create an observable out of a generator and tell RxJS when to pull the next value instead of relying on the official implementation which creates backpressure.

createIteratorSubject.js

const { BehaviorSubject, Subject } = require('rxjs')
const { map, tap, withLatestFrom } = require('rxjs/operators')

const createIteratorSubject = (
  iterator,
) => {
  const iterator$ = (
    new BehaviorSubject()
  )

  const pushNextValue = ({
    done,
    value,
  }) => {
    done
    && value === undefined
    ? (
      iterator$
      .complete()
    )
    : (
      iterator$
      .next(value)
    )
  }

  iterator$
  .push = (
    value,
  ) => (
    pushNextValue(
      iterator
      .next(value)
    )
  )

  iterator$
  .push()

  return iterator$
}

module.exports = createIteratorSubject

I found the above snippet difficult to read. Consider using a different name for subject, as well as a more compact format overall. For example:

const { BehaviorSubject } = require('rxjs')

function createIteratorSubject(iterator) {
  const subject$ = new BehaviorSubject();

  subject$.push = function(value) {
    const {done, value} = iterator.next(value);.

    if (done && value === undefined) {
        subject$.complete();
    } else {
        subject$.next(value);
    } 
  }

  subject$.push()

  return subject$
}

module.exports = createIteratorSubject

What an interesting code format, do you have an auto formatter for that?

@anilanar I'd love to have an auto-formatter and will be looking into using ESLint rules to achieve it (if that's even possible).

Unlike Prettier, there are a set of rules I follow so it's easy for someone else to replicate and get the same results. At my last job, you'd be unable to tell my code apart from my coworkers'. In fact, there was one bug we ended up fixing in separate PRs with the exact same solution line-by-line.

@anilanar I now have an eslint extension available.