HTTP/2

HTTP/2

node:http2 is a separate, Stability 2 – Stable implementation built on nghttp2. Its unit of work is the stream, not the connection: one TCP socket carries many numbered streams at once, headers travel compressed with HPACK, and requests do not block each other. Pseudo-headers (:status, :path) replace the request line.

Three multiplexed requests over one connectionJavaScript

import { createServer, connect } from 'node:http2';
const server = createServer().on('stream', (s, h) => {
  s.respond({ ':status': 200 }); s.end(`you asked for ${h[':path']}`);
});
server.listen(8080, '127.0.0.1', () => {
  const client = connect('http://127.0.0.1:8080'); let done = 0;
  for (const path of ['/a', '/b', '/c']) {
    const stream = client.request({ ':path': path }).setEncoding('utf8');
    stream.on('data', (d) => console.log('stream', stream.id, '->', d.trim()));
    stream.on('close', () => { if (++done === 3) { client.close(); server.close(); } });
  }
});

Output

stream 1 -> you asked for /a
stream 3 -> you asked for /b
stream 5 -> you asked for /c

The ids are 1, 3 and 5 — client-initiated streams are odd-numbered — and all three were open at once. createServer speaks cleartext h2c, for use behind a proxy that has terminated TLS; createSecureServer with key and cert is the public-facing form, where ALPN negotiates h2, and allowHTTP1: true makes it fall back to the compatibility (req, res) API.

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