async-iterable-stream

async-iterable-stream

A readable stream which can be iterated over using a for-await-of loop.

The AsyncIterableStream constructor accepts an asyncIteratorFactory as argument; this can be either an async generator function or a regular function which returns an async iterator. In the case of a generator function, the asyncIteratorFactory should yield a sequence of Promise objects which resolve one at a time in the same order as they appear in the sequence.

For a concrete implementation of AsyncIterableStream, see WritableAsyncIterableStream: https://github.com/SocketCluster/writable-async-iterable-stream

Installation

npm install async-iterable-stream

Usage

The AsyncIterableStream class exposes the following methods:

• [Symbol.asyncIterator]: Makes the instance iterable using a for-await-of loop.
• next: Returns a Promise which will resolve an object in the form {value: data, done: boolean} whenever some data is received or when the stream ends.
• once: Similar to next() except that the resolved value will be the raw data and it will not resolve when the stream ends. Note that once once() is called, it cannot be cancelled; the affected closure will stay in memory until either once() resolves or until the stream is ended or garbage collected.

// Consume data objects from asyncIterableStream as they are written to the stream.
(async () => {
  for await (let data of asyncIterableStream) {
    console.log(data);
  }
})();

// Consume only the next data object which is written to the stream.
(async () => {
  let data = await asyncIterableStream.once();
  console.log(data);
})();