Nodejs: Fetch Google Analytic data with googleapi module

index.js

const { google } = require('googleapis');
const fs = require('fs');

const analyticsreporting = google.analyticsreporting('v4');

const setAuth = () => {
    // Obtain user credentials to use for the request
    const auth = new google.auth.GoogleAuth({
        keyFile: 'your_service_account.json',
        scopes: ['https://www.googleapis.com/auth/analytics']
    });

    google.options({auth});
};

// https://developers.google.com/analytics/devguides/reporting/core/v4/rest/v4/reports/batchGet
async function batchGet() {
    // set auth
    setAuth();

    const res = await analyticsreporting.reports.batchGet({
        requestBody: {
            reportRequests: [
                {
                    viewId: '210916xxx',
                    dateRanges: [
                        {
                            startDate: '2022-02-01',
                            endDate: '2022-02-22',
                        },
                        {
                            startDate: '14daysAgo',
                            endDate: '7daysAgo',
                        },
                    ],
                    metrics: [
                        {
                            expression: 'ga:sessions',
                        },
                    ],
                    dimensions: [
                        {
                            name:"ga:browser"
                        },
                        {
                            name:"ga:clientId"
                        }
                    ],
                },
            ],
        },
    });

    return res.data;
}

// https://developers.google.com/analytics/devguides/reporting/core/v4/rest/v4/userActivity/search
async function userSearch() {
    // set auth
    setAuth();

    const res = await analyticsreporting.userActivity.search({
        requestBody: {
            viewId: '210916xxx',
            user: {
                'type': 'CLIENT_ID',
                'userId': '409760102.1643249907'
            },
            dateRange: {
                startDate: '2022-02-01',
                endDate: '2022-02-22',
            }
        }
    });
    
    return res.data;
}

batchGet().then(data => {
    const jsonString = JSON.stringify(data);
    fs.writeFile("output.json", jsonString, 'utf8', function (err) {
        if (err) {
            console.log("An error occured while writing JSON Object to File.");
            return console.log(err);
        }
     
        console.log("JSON file has been saved.");
    });
})
.catch(e => console.log('error: ', e));