[initial steps]

Navigate to functions directory.

install firebase CLI (to use npm install node js)

npm install -g firebase-tools

install dependencies

npm install

login to firebase

firebase login

firebase init

Do not overwrite package.json

Deploy your Cloud Function for Firebase with

firebase deploy --only functions:dialogflowFirebaseFulfillment

Source: https://firebase.google.com/docs/cli/#setup

https://dialogflow.com/docs/how-tos/getting-started-fulfillment#moving_fulfillment_outside_of_the_editor

Database used: cloud firestore https://firebase.google.com/docs/firestore