Sources and queues

Helpers that create or merge iterations.

range

[...range(0, 3)]; // => [0, 1, 2]
[...range(0, 10, 5)]; // => [0, 5]
[...range(3, 0)]; // => [3, 2, 1]
await chain(range(1)).take(3).toArray(); // => [1, 2, 3]

Without an end the range is endless. A step that points away from the end gives an empty range, and a step of 0 throws a RangeError.

See range in the API reference.

mux

Merges several inputs into one. Items arrive as they are produced, so the order across inputs is not defined; the order within each input is kept.

const merged = await chain(
    mux([
        [1, 2, 3],
        [10, 20, 30],
    ]),
).toArray();
// merged.filter((n) => n < 10) => [1, 2, 3]
// merged.filter((n) => n >= 10) => [10, 20, 30]

See mux in the API reference.

Fifo

An asynchronous queue that is also an AsyncIterable. Producers call send (it waits when the queue is full, which gives back pressure; set the limit with new Fifo({ highWatermark })) and finish with end(). A send after end() rejects with chan is closed.

const fifo = new Fifo<number>();

const consumed = (async () => {
    const items: number[] = [];
    for await (const item of fifo) {
        items.push(item);
    }
    return items;
})();

await fifo.send(1);
await fifo.send(2);
fifo.end();

await consumed; // => [1, 2]

end(error) finishes the queue with an error: consumers get the items already queued, then the error is thrown from their iteration.

See Fifo and FifoOptions.