Sieve of Eratosthenes with AsyncIterator

eratosthenes.js

var AsyncIterator = require('asynciterator'),
    TransformIterator = AsyncIterator.TransformIterator;

function EratosthenesIterator(base) {
  TransformIterator.call(this);
  base = base || AsyncIterator.range(2);
  base.once('data', prime => {
    this._push(prime);
    this.source = new EratosthenesIterator(base.filter(n => n % prime));
  });
}
TransformIterator.subclass(EratosthenesIterator);

module.exports = EratosthenesIterator;