React, JavaScript, Architecture.
fs.readFile(indexFile, 'utf8', (err, data) => { if (err) { console.error('Something went wrong:', err); return res.status(500).send('Oops!!'); } return res.send( data.replace('<div id="root"></div>', `<div id="root">${appString}</div>`) ); }); }); app.listen(3000, () => { console.log('Server is