writable-async-iterable-stream

writable-async-iterable-stream

An async stream which can be iterated over using a for-await-of loop and which can be written to.

The WritableAsyncIterableStream class extends the AsyncIterableStream class.
See https://github.com/SocketCluster/async-iterable-stream

Installation

npm install writable-async-iterable-stream

Usage

Consume a stream and write to it asynchronously:

let iterableStream = new WritableAsyncIterableStream();

async function consumeAsyncIterable(asyncIterable) {
  // Consume iterable data asynchronously.
  for await (let packet of asyncIterable) {
    console.log('Packet:', packet);
  }
}
consumeAsyncIterable(iterableStream);

setInterval(() => {
  // Write data to the stream asynchronously,
  iterableStream.write(`Timestamp: ${Date.now()}`);
}, 100);

Consume a stream using a while loop:

let iterableStream = new WritableAsyncIterableStream();

async function consumeAsyncIterable(asyncIterable) {
  // Consume iterable data asynchronously.
  // Works in older environments.
  let asyncIterator = stream.createAsyncIterator();
  while (true) {
    let packet = await asyncIterator.next();
    if (packet.done) break;
    console.log('Packet:', packet.value);
  }
}
consumeAsyncIterable(iterableStream);

setInterval(() => {
  // Write data to the stream asynchronously,
  iterableStream.write(`Timestamp: ${Date.now()}`);
}, 100);

Consume a filtered stream using an async generator:

let iterableStream = new WritableAsyncIterableStream();

// Creates an async generator which only produces packets which are allowed by the
// specified filterFunction.
async function* createFilteredStreamGenerator(fullStream, filterFunction) {
  for await (let packet of fullStream) {
    if (filterFunction(packet)) {
      yield packet;
    }
  }
};

async function consumeAsyncIterable(asyncIterable) {
  // Consume iterable data asynchronously.
  for await (let packet of asyncIterable) {
    console.log('Packet:', packet);
  }
}

// The filter function will only include strings which end with the number 5.
function filterFn(data) {
  return /5$/.test(data);
}
let filteredStreamGenerator = createFilteredStreamGenerator(iterableStream, filterFn);

consumeAsyncIterable(filteredStreamGenerator);

setInterval(() => {
  // Write data to the stream asynchronously,
  iterableStream.write(`Timestamp: ${Date.now()}`);
}, 100);

Consume only the next data object which will be written to the stream:

let iterableStream = new WritableAsyncIterableStream();

(async () => {
  let data = await iterableStream.once();
  console.log(data);
})();

setInterval(() => {
  // Write data to the stream asynchronously,
  iterableStream.write(`Timestamp: ${Date.now()}`);
}, 100);

See test/ directory for additional examples.