Headers go first

1const http = require('node:http');2const server = http.createServer((req, res) => {3  res.setHeader('x-step', 'one');4  res.write('part 1, ');5  console.log('headersSent: ' + res.headersSent);6  try {7    res.setHeader('x-late', 'two');8  } catch (err) {9    console.log(err.code);10  }11  res.end('part 2');12});13server.listen(0, async () => {14  const { port } = server.address();15  const r = await fetch(`http://localhost:${port}`);16  console.log('x-step: ' + r.headers.get('x-step'));17  console.log('x-late: ' + r.headers.get('x-late'));18  console.log(await r.text());19  server.close();20});