server.js

const express = require('express');
const cors = require('cors');
const app = express();

const rootDir = __dirname + '/app';

app.use(cors());
app.use(express.static(rootDir));

app.get('*', function(req, res) {
  res.header('Cache-Control', 'private, no-cache, no-store, must-revalidate');
  res.sendfile(rootDir + '/index.html');
});

app.listen(3000, function() {
  console.log('App listening on port 3000');
  console.log('App source directory is "' + rootDir + '"');
});