# Node fetch / axios

For plain HTTP calls in Node (without a headless browser), two stacks dominate.

## Modern: `undici` (built-in fetch)

Node 18+ ships `fetch` from `undici`. For HTTP-CONNECT proxies you need `undici`'s `ProxyAgent`:

```bash
npm i undici
```

```js
import { fetch, ProxyAgent } from "undici";

const agent = new ProxyAgent(
  "http://helo_s1a2b3c4d5e-type-res-region-us:PASSWORD@gate.helodata.io:7777"
);

const res = await fetch("https://ipv4.icanhazip.com", { dispatcher: agent });
console.log((await res.text()).trim());
console.log("Exit IP:", res.headers.get("x-helodata-exit-ip"));
```

For ISP, swap the URL to `http://helo_s1a2b3c4d5e:PASSWORD@198.51.100.42:8000`.

## SOCKS5 with undici

```bash
npm i socks-proxy-agent
```

```js
import { SocksProxyAgent } from "socks-proxy-agent";
import { fetch } from "undici";

const agent = new SocksProxyAgent(
  "socks5://helo_s1a2b3c4d5e-type-res-region-us:PASSWORD@gate.helodata.io:7777"
);
const res = await fetch("https://ipv4.icanhazip.com", { dispatcher: agent });
```

## axios

```bash
npm i axios https-proxy-agent
```

```js
import axios from "axios";
import { HttpsProxyAgent } from "https-proxy-agent";

const agent = new HttpsProxyAgent(
  "http://helo_s1a2b3c4d5e-type-res-region-us:PASSWORD@gate.helodata.io:7777"
);

const res = await axios.get("https://ipv4.icanhazip.com", {
  httpAgent: agent,
  httpsAgent: agent,
  proxy: false,                            // disable axios's own proxy resolution
});
console.log(res.data.trim());
```

> Set `proxy: false` on the axios call — otherwise axios will second-guess your agent using its own `env`-based proxy logic.

## ISP rotation

```js
import fs from "node:fs";
import { fetch, ProxyAgent } from "undici";

const lines = fs.readFileSync("isp.txt", "utf8").trim().split("\n");
let i = 0;

async function fetchOne(url) {
  const [ip, port, user, pass] = lines[i++ % lines.length].split(":");
  const agent = new ProxyAgent(`http://${user}:${pass}@${ip}:${port}`);
  return fetch(url, { dispatcher: agent });
}
```

## Sticky sessions (residential)

```js
import crypto from "node:crypto";

function sessionUrl(country = "us") {
  const sid = crypto.randomBytes(4).toString("hex");
  const user = `helo_s1a2b3c4d5e-type-res-region-${country}-session-${sid}-sesstime-10`;
  return `http://${user}:PASSWORD@gate.helodata.io:7777`;
}
```

## Verify

```js
const ip = (await (await fetch("https://ipv4.icanhazip.com", { dispatcher: agent })).text()).trim();
console.log(ip);
```

## Common pitfalls

* **`HTTP_PROXY` envvar mode in `undici`** — pre-1.x undici didn't honor env vars. Use `ProxyAgent` explicitly.
* **axios + `proxy: { host, port }`** — that syntax does **not** use HTTP-CONNECT, it tries a request-rewrite that breaks HTTPS. Always use an `httpAgent`/`httpsAgent`.
* **Connection reuse** — `undici.Agent` (the default dispatcher) pools connections; if you mint a new `ProxyAgent` per request you lose the pool. For ISP, share one agent per IP.


---

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