JSHow to use proxies with Node.js

npm install undici socks-proxy-agent

// check-ip.mjs
import { fetch, ProxyAgent } from 'undici';

const dispatcher = new ProxyAgent({
  uri: 'http://gw.proxonym.com:8000',
  token: `Basic ${Buffer.from('USERNAME:PASSWORD').toString('base64')}`,
});

const res = await fetch('https://api.ipify.org', { dispatcher });
console.log('Exit IP:', await res.text());
await dispatcher.close();

// sessions.mjs
import { randomBytes } from 'node:crypto';
import { fetch, ProxyAgent } from 'undici';

function proxonymAgent({ country, state, city, asn, session, lifetime = 30 } = {}) {
  let user = 'USERNAME';
  if (country) user += `-country-${country}`;
  if (state) user += `-state-${state}`;
  if (city) user += `-city-${city}`;
  if (asn) user += `-asn-${asn}`;
  if (session) user += `-session-${session}-lifetime-${lifetime}`;
  return new ProxyAgent({
    uri: 'http://gw.proxonym.com:8000',
    token: `Basic ${Buffer.from(`${user}:PASSWORD`).toString('base64')}`,
  });
}

// Rotating: a new agent opens a new connection, so each request gets a new IP
for (let i = 0; i < 3; i++) {
  const agent = proxonymAgent({ country: 'us' });
  const res = await fetch('https://api.ipify.org', { dispatcher: agent });
  console.log('rotating', await res.text());
  await agent.close();
}

// Sticky: one agent and one session ID keep the same IP for up to 30 minutes
const sticky = proxonymAgent({ country: 'us', session: randomBytes(4).toString('hex') });
for (let i = 0; i < 3; i++) {
  const res = await fetch('https://api.ipify.org', { dispatcher: sticky });
  console.log('sticky', await res.text());
}
await sticky.close();

const agent = proxonymAgent({ country: 'de', city: 'berlin' });
const res = await fetch('https://ipinfo.io/json', { dispatcher: agent });
const { ip, city, country } = await res.json();
console.log(ip, city, country);
await agent.close();

// socks5.mjs
import https from 'node:https';
import { SocksProxyAgent } from 'socks-proxy-agent';

const agent = new SocksProxyAgent('socks5h://USERNAME-country-gb:[email protected]:1080');

https.get('https://api.ipify.org', { agent }, (res) => {
  let body = '';
  res.on('data', (chunk) => (body += chunk));
  res.on('end', () => console.log('Exit IP:', body));
});

// retry.mjs
import { fetch, ProxyAgent } from 'undici';

const dispatcher = new ProxyAgent({
  uri: 'http://gw.proxonym.com:8000',
  token: `Basic ${Buffer.from('USERNAME-country-us:PASSWORD').toString('base64')}`,
});

// The innermost cause carries the gateway status, e.g. "Proxy response (407) !== 200 when HTTP Tunneling"
function rootCause(err) {
  let cause = err;
  while (cause?.cause) cause = cause.cause;
  return cause;
}

async function fetchWithRetry(url, tries = 3) {
  for (let attempt = 1; ; attempt++) {
    try {
      const res = await fetch(url, { dispatcher, signal: AbortSignal.timeout(60_000) });
      if ((res.status !== 429 && res.status < 500) || attempt === tries) return res;
      await res.body?.cancel();
    } catch (err) {
      const reason = rootCause(err).message;
      console.error(`attempt ${attempt}:`, reason);
      // 402, 403 and 407 will not go away on a retry
      if (/\((402|403|407)\)/.test(reason) || attempt === tries) throw err;
    }
    await new Promise((resolve) => setTimeout(resolve, 1000 * attempt));
  }
}

const res = await fetchWithRetry('https://example.com');
console.log('Status:', res.status);
await dispatcher.close();