javascript - Waiting for a forEach to finish before return from my promise / function

Question

I am using Firebase Cloud Firestore, however, I think this may be more of a JavaScript asynchronous vs synchronous promise return issue.

I am doing a query to get IDs from one collection, then I am looping over the results of that query to lookup individual records from another collection based on that ID.

Then I want to store each found record into an array and then return the entire array.

results.length is always 0 because return results fires before the forEach completes. If I print results.length from inside the forEach it has data.

How can I wait until the forEach is done before returning from the outer promise and the outer function itself?

         getFacultyFavoritesFirebase() {
            var dbRef = db.collection("users").doc(global.user_id).collection("favorites");
            var dbQuery = dbRef.where("type", "==", "faculty");
            var dbPromise = dbQuery.get();
            var results = [];
            return dbPromise.then(function(querySnapshot) {
                querySnapshot.forEach(function(doc) {
                  var docRef = db.collection("faculty").doc(doc.id);
                  docRef.get().then(function(doc) {
                    if (doc.exists) {
                        results.push(doc);
                    }
                  })
                });
                console.log(results.length);
                return results;
            })
            .catch(function(error) {
                console.log("Error getting documents: ", error);
            });
          }

Answer 1

Waitting for answers