gcp-gsuite-service-account-auth-nodejs.js

const { google } = require('googleapis');
const privatekey = require('./private-key.json'); // This was downloaded when you created your Service Account Key

const scopes = ['https://www.googleapis.com/auth/gmail.settings.basic'];

const auth = async (user) => {

    try {

        const jwtClient = new google.auth.JWT(
            privatekey.client_email,
            null,
            privatekey.private_key,
            scopes,
            user // User who will be impersonated with this JWT client
        );

        await jwtClient.authorize();

        return jwtClient;

    } catch (err) {

        return err;

    }

}

// Users who will be impersonated
const users = [
    'user1@email.com',
    'user2@email.com',
    'user3@emai.com'
];

for (const user of users) {

    auth(user).then((jwtClient) => {

        // make request with JWT Client

    });

}