NodeJS code that for a MongoDB set of collections --generates in code the _id value for new documents that you insert

var express = require('express');
var router = express.Router();
var mongodb = require('mongodb');
var mongoDBURI = process.env.MONGODB_URI || 'mongodb://login:PASSWORD@ds23315.mlab.com:55315/db';

//to process data sent in on request need body-parser module
var bodyParser = require('body-parser');
var path = require('path'); //to work with separtors on any OS including Windows
var querystring = require('querystring'); //for use in GET Query string of form URI/path?name=value
router.use(bodyParser.json()); // for parsing application/json
router.use(bodyParser.urlencoded({extended: true})); // for parsing application/x-www-form-urlencode
           

module.exports.storeData = function (req, res, next) {
           

 mongodb.MongoClient.connect(mongoDBURI, function (err, db) {
             if (err) throw err;

             /**************************************************************************
              * IMPORTANT:  this is how you generate  a random number for  3IDs that 
              * you will need for the collections cusomerID, billinID and   shippingID
              *    WHY?  the retrieve _id  info after and  insert (see below)  does not seem
              *     to function properly on Heroku 
              *    so to know the ID we simply generate it in code  rather than
              *     autogenerate it for the documents we newly insert into the CUSOTMERS, BILLING, SHIPPING
              *      for ORDERS we allow the system to autogenerate its  _id
              */
             var customerID = Math.floor((Math.random() * 1000000000000) + 1);
             var billingID = Math.floor((Math.random() * 1000000000000) + 1);
             var shippingID = Math.floor((Math.random() * 1000000000000) + 1);

 //customer collection operation
             var CUSTOMERS = db.collection('CUSTOMERS');
             /*CUSTOMERS.deleteMany({}, function (err, result) {
             if (err) throw err;
             });*/

 var customerdata = {
             _id: customerID,
             FIRSTNAME: shipment_info['fname'],
             LASTNAME: shipment_info['lname'],
             STREET: shipment_info['add1'] + ' ' + shipment_info['add2'],
             CITY: shipment_info['city'],
             STATE: shipment_info['state'],
             ZIP: shipment_info['zipcode'],
             PHONE: shipment_info['phone']
             };

             CUSTOMERS.insertOne(customerdata, function (err, result) {
                 if (err) throw err;
                })l