server.js

const express = require('express');
const favicon = require('express-favicon');
const path = require('path');
const port = process.env.PORT || 8080;
const app = express();
app.use(favicon(__dirname + '/build/favicon.ico'));
// the __dirname is the current directory from where the script is running
app.use(express.static(__dirname));
app.use(express.static(path.join(__dirname, 'build')));
app.get('/ping', function (req, res) {
  return res.send('pong');
});
app.get('/*', function (req, res) {
  res.sendFile(path.join(__dirname, 'build', 'index.html'));
});

app.use(function(req, res, next) {
  res.header("Access-Control-Allow-Origin", "*"); // update to match the domain you will make the request from
  res.header('Access-Control-Allow-Methods: GET, POST, PATCH, PUT, DELETE, OPTIONS');
  res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");
  next();
});

app.listen(port)