index.js

const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp(functions.config().firebase);

var database = admin.database();

exports.helloWorld = functions.https.onRequest((request, response) => {
    response.send("Hello from Firebase!");
});

exports.textToLength = functions.https.onRequest((request, response) => {
    var text = request.query.text;
    var textLength = text.length;
    response.send(String(textLength));
});

exports.newNodeDetected = functions.database.ref('users/{userId}/Name')
    .onWrite((change, context) => {
        var oldName = change.before.val();
        var newName = change.after.val();
        var userId = context.params.userId;
        database.ref('metadata/lastChangedName/').set(userId + " changed his name from " + oldName + " to " + newName);

        return null;
    });

exports.pushDataEveryMinute = functions.pubsub.schedule('every 1 minutes').onRun((context) => {
    var date = new Date();
    database.ref("metadata/lastUpdate/").set(date.getTime());

    return null;
});