server.js

  var app = express();
const indexPath = path.join(__dirname, './public/index.html')
const publicPath = express.static(path.join(__dirname, './public'))

    app.use('/public', publicPath)
    app.use('/graphql', graphQLHTTP({graphiql: true, schema, pretty: true})); // graphql endpoint
    app.get('/', function (_, res) { res.sendFile(indexPath) });
  let http = require('http');
  let server = http.createServer(app);
  server.listen(4000, () => console.log("app in 4000"));