dotenv

                                    // when yours .env is in other place then default, you can set path to it

const path = require('path')
require('dotenv').config({ path: path.resolve(__dirname, '../../.env') }); //use as many '../' as you need

                                    
$ npm install dotenv

//--------------------

on file .env 
//--------------------
DB_HOST=localhost
DB_USER=root
DB_PASS=s1mpl3
DB_NAME=banco_de_dados
DB_PORT=3306
//--------------------

import the config from .env file 
//--------------------

require('dotenv').config()
module.exports = {
    username:process.env.DB_USER,
    password:process.env.DB_PASS,
    database:process.env.DB_NAME,
    host:process.env.DB_HOST,
    dialect:"mysql"
}

                                    # For python users only
pip install python-dotenv

                                    //first install this
npm install dotenv

//then add this on the top of the your code
require("dotenv").config();

//first create file with name of .env 
DB_HOST=localhost
DB_USER=root
DB_PASS=s1mpl3

//then use it 
const db = require('db')
db.connect({
  host: process.env.DB_HOST,
  username: process.env.DB_USER,
  password: process.env.DB_PASS
})