Async Generator Queue

example.ts

import { createQueue } from './queue.js';

const fakeAsyncCall = (i: number) =>
    new Promise<void>((resolve) =>
        setTimeout(() => {
            console.log(i);
            resolve();
        }, 1000)
    );

const queue = createQueue(2);

console.log('start');

for (let i = 0; i < 10; i++) {
    queue.next(() => fakeAsyncCall(i));
}

// drain
await queue.next();

console.log('end');

queue.ts

export function createQueue(size: number = Infinity) {
    const queue: Set<Promise<void>> = new Set();

    const queueGenerator = (async function*(): AsyncGenerator<void>  {
        while (true) {
            if (queue.size >= size) {
                await Promise.any(queue);
            }

            const item = (yield) as () => Promise<void>;
            if (item) {
                const promise = Promise.resolve(item()).finally(function () {
                    queue.delete(promise);
                });
                queue.add(promise);
            } else {
                await Promise.all(queue);
            }
        }
    })();

    queueGenerator.next();

    return queueGenerator;
}