I just want to save my data into firestore. but according to data structure, I have to create new collection into document. but my js are not working. Could you check it? Is it possible?

/*
   po   : parent collection
     po-{}: parent document
      items: sub collection
        item-${} : sub document
*/


items.map(async(item) => {
  await setDoc(doc(firestore, "po", `po-${po_number}`,'items', `item-${item.item_id}` ), {
    id:       item.item_id,
    quantity: item.quantity,
    received: item.received,
    rate:     item.rate,
    amount:   item.rate * item.quantity
  });
})