Cloud Firestore | Getting all documents given a list of ObjectIds

Question

Cloud Firestore doesn't yet support batch read of documents in a collection and so the next best thing is to use firestore.getAll() to retrieve documents given an array of ObjectId's as given in this link.

A similar question has already been posted and the above function was the answer to the question. But when I run the same snippet it somehow isn't working. Can someone please tell me why?

db.collection("users")
        .doc(uid)
        .get()
        .then(data => {
            // return array of accountId's associated with user
            return data.data().accounts;
        })
        .then(arr => {
            console.log(arr);
            if (!arr) {
                res.json({ message: "no associated accounts" });  // check if array is empty
            }
            let userAccounts = [], docRefs = []; 
            arr.forEach(id => docRefs.push(db.doc(`accounts/${id})`)));     // dynamically creating DocumentReferences for each _id
            console.log(docRefs);     // valid output -> an array of 2 DocumentReference() objects
            db.getAll(...docRefs).then(docs => {     // I
                docs.forEach(doc => {
                    if (doc.exists) {
                        console.log(doc.data());     // II
                        userAccounts.push(doc.data());
                    }
                });
            });
            console.log(userAccounts);               // III
            res.json(userAccounts);
        })
        .catch(err => {
            res.status(500).json({
                status: err.code,
                message: err.message
            });
        });

• I. Since it's a dynamically generated array, I've used the spread operator.
• II. This line is never executed as there is no output for this console.log() statement, not even an undefined.
• III. Therefore the userAccounts is still [] after this, since II is never executed and neither is the push() after that and so, this is the response I get. No errors.

P.S. The arr is fine. I've cross-checked with the db. The db variable is a firestore() object.