how to deploy a react already existing code on github to heroku code example

Example: deploy react app to heroku

const path = require('path');const express = require('express');const app = express();const publicPath = path.join(__dirname, '..', 'public');const port = process.env.PORT || 3000;app.use(express.static(publicPath));app.get('*', (req, res) => {   res.sendFile(path.join(publicPath, 'index.html'));});app.listen(port, () => {   console.log('Server is up!');});