{readyState: 0, getResponseHeader: function, getAllResponseHeaders: function, setRequestHeader: function, overrideMimeType: function, …}

o - jquery-ui.min.js:62909
dispatch - jquery.3.2.1.min.js:3:10322

$(document).on('submit','#reserve form', function(){
  event.preventDefault();
  var data = {
   /*some data created to send*/
 };
      /*after i have data, i show it back to the user
      to assure is the data he wants to email
      then add a confirm button and a reject button afterwards*/
    });

$(document).on('click', '#reserve #confirm_button', function(){
  var data = {

    /*gets data again*/
  };
  $.ajax({
    url: '/sendEmail',
    data: data,
    method: 'POST'
  }).then(function (response) {
    console.log(response);
  }).catch(function (err){
    console.error(err);
  });
});

var express = require('express');
var path = require('path');
var favicon = require('serve-favicon');
var logger = require('morgan');
var cookieParser = require('cookie-parser');
var bodyParser = require('body-parser');
const nodemailer = require('nodemailer');
var index = require('./routes/index');

var app = express();

app.post('/sendEmail', function (req, res) {

  var message = "message to be sent"

  let transporter = nodemailer.createTransport({

    service: 'gmail',
    secure: false,
    port: 25,
    auth: {
      user: 'email@gmail.com',
      pass: 'password'
    },
    tls: {
      rejectUnathorize: false
    }
  });
  let HelperOptions = {

    from: '"Email" <email@gmail.com>',
    to: req.body.email,
    subject: 'Subject',
    text: message
  };
  transporter.sendMail(HelperOptions, function(error, info){

    if(error){
      res.send(false);
      return console.log(error);
    }
    res.send(true);
    console.log(info);
  });
});

module.exports = app;