Example Firestore interaction w/JS

firestore.js

  query.get()
      .then((doc) => {
        if (!doc.exists) {
          console.log('Item: No such document for:', loggingEvent);
          collection.add(item)
              .then((documentReference) => {
                console.log(`Added item with ref/id: ${documentReference.id}`);
                track('Wrote Message to DB Completed', {
                  team: item.team,
                  channel: item.channel,
                });
              })
              .then((documentReference) => {
                // Dual-write event without message for summary
                const docPath = (item.type === 'message') ? 'Messages' : 'Reactions';
                const summaryCollection = db.collection('Summaries').doc(docPath).collection(item.team)
                    .doc(item.channel).collection(item.channel);

                const itemSafeCopy = Object.assign({}, item);
                if (itemSafeCopy.type === 'message') {
                  delete itemSafeCopy.message;
                }

                summaryCollection.add(itemSafeCopy)
                    .then((documentReference) => {
                      console.log(`Dual-wrote item for summary with ref/id: ${documentReference.id}`);
                      track('Wrote Message to DB Copy to Summary Completed', {
                        team: item.team,
                        channel: item.channel,
                      });
                    });
              });
        } else {
          console.log('Item: Document already exists (skipping) for:', loggingEvent);
        }
      })
      .catch((err) => {
        console.log('Item: Error getting document for:', loggingEvent, 'Error:', err);
      });