app.js

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');
var cors = require('cors');

var router = require('./routes');

var app = express();

app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'jade');

app.use(logger('dev'));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false }));
app.use(cookieParser());
app.use(express.static(path.join(__dirname, 'public')));
app.use(favicon(path.join(__dirname, 'public', 'favicon.ico')));

var isOriginValid = function (req, callback) {
  var corsOptions;
  if (req.header('Origin') === "https://alinalodahl.herokuapp.com/contact") {
    corsOptions = { origin: true }
  }else{
    corsOptions = { origin: false } // disable CORS for this request
  }
  callback(null, corsOptions) // callback expects two parameters: error and options
}

app.use('/api/contact', cors(isOriginValid), router);
app.use('/', index);
console.log("Your app is listening at PORT 3000");

app.use(function(req, res, next) {
  var err = new Error('Not Found');
  err.status = 404;
  next(err);
});

app.use(function(err, req, res, next) {
  res.locals.message = err.message;
  res.locals.error = req.app.get('env') === 'development' ? err : {};

  res.status(err.status || 500);
  res.render('error');
});

module.exports = app;