nodejs_email_oauth1.ts

// import required dependencies
import dotenv from 'dotenv';
import nodemailer from 'nodemailer';
import { google } from 'googleapis';
const OAuth2 = google.auth.OAuth2;

// init dotenv
dotenv.config();

// get environment variables
const OAUTH_EMAIL = process.env.OAUTH_EMAIL || '' as string;
const OAUTH_CLIENT_ID = process.env.OAUTH_CLIENT_ID || '' as string;
const OAUTH_CLIENT_SECRET = process.env.OAUTH_CLIENT_SECRET || '' as string;
const OAUTH_REFRESH_TOKEN = process.env.OAUTH_REFRESH_TOKEN || '' as string;