Observable: Take a random number of integers

observable-take-random-n.js

function* range(from, to) {
  for (let i = from; i <= to; ++i) {
    yield i;
  }
}

function take(source, n) {
  if (n <= 0) {
    return Observable.from([]);
  }
  return new Observable(sink => {
    let count = 0;
    return source.subscribe({
      next(v) {
        sink.next(v);
        if (++count === n) {
          sink.complete();
        }
      },
      error(e) { sink.error(e) },
      complete() { sink.complete() },
    });
  });
}

let observable = take(
  Observable.from(range(0, Number.POSITIVE_INFINITY)),
  Math.round(Math.random() * 100)
);

observable.subscribe(console.log);