Here's an example:

// Each item has a few pipelined actions that take time indicated by the number. So the first item does 3 operations each taking 100ms
async function* gen() {
  yield* [[100, 100, 100, 'a'], [100, 100, 100, 'b'], [10, 10, 10, 'c'], [10, 10, 10, 'd'], [10, 10, 10, 'e'], [10, 10, 10, 'f']];
}
for await (const i of gen.map(async item => {
	await new Promise(resolve => setTimeout(resolve, item.shift()));
  return item;
}).map(async item => {
	await new Promise(resolve => setTimeout(resolve, item.shift()));
  return item;
}).map(async item => {
	await new Promise(resolve => setTimeout(resolve, item.shift()));
  return item;
})) {
  // This will after summation of all the times in each array.
  console.log(item.shift());
}

async function* map(tasks, n) {
  try {
    // Start n work
    const parallel = new Set();
    for (let i = 0; !tasks.done && i < n; ++i) {
      parallel.add(makeWork((await tasks.next()).value));
    }
    // Process the work yielding the first one done in the set of n work
    while (parallel.length != 0 && !tasks.done) {
      const task = await Promise.race([...parallel].map(t => t.promise));
      parallel.delete(task);
      yield task;
      // Add 1 more work
      parallel.add(makeWork((await tasks.next()).value));
    }
  } finally {
    console.log('map done');
    tasks?.return();
  }
}