open-async-iterator

A small utility for creating async iterators that can be controlled externally.

This allows you to take events from a callback-based context (such as Node.js streams), and pipe those events into an async iterator, where it can be used in any function that uses async operations.

Installation

npm install @facetlayer/open-async-iterator

Usage

import { openAsyncIterator } from '@facetlayer/open-async-iterator'

// Create the iterator.
const { send, done, iterator } = openAsyncIterator<number>()

// The 'driver' code sends values to the iterator and marks it as done.
send(1);
send(2);
send(3);
done();

// Then a different part of the code consumes the iterator (this can happen in parallel)
for await (const value of iterator) {
  console.log(value) // Outputs: 1, 2, 3
}

API

openAsyncIterator<T>()

Creates a new open async iterator.

Returns:

• send(value: T) - Function to send a value to the iterator
• done() - Function to mark the iterator as complete
• iterator - The async iterator object

Error Handling

Calling send() after done() will throw an error:

const { send, done } = openAsyncIterator()

done()
send(1) // Throws: "usage error: called send() after done()"