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What is a Transport?

A Transport is a reusable network context handle for transport level settings such as browser profile, OS emulation, proxy, and TLS verification options. Use it when you want reusable transport settings without creating a full session per proxy, for example when you keep one transport handle per proxy in a long running worker.

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createTransport()

Create a reusable transport.

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Signature

function createTransport(options?: CreateTransportOptions): Promise<Transport>

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Options

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proxy
string
Proxy URL for all requests made through this transport. Support depends on the native layer and proxy scheme.
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browser
BrowserProfile
default:"chrome_142"
Browser fingerprint profile to use for this transport.
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os
EmulationOS
default:"macos"
Operating system to emulate for this transport.
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insecure
boolean
default:"false"
When true, accepts invalid/self-signed certificates. Use only if you understand the security tradeoffs.
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poolIdleTimeout
number
Native transport idle timeout option (ms).
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poolMaxIdlePerHost
number
Native transport per host idle connection limit option.
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poolMaxSize
number
Native transport total connection limit option.
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connectTimeout
number
TCP connect timeout (ms).
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readTimeout
number
Read timeout (ms).

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Using a transport with fetch()

Pass the transport via RequestInit.transport. 
import { createTransport, fetch } from "wreq-js";

const transport = await createTransport({
  proxy: "http://user:pass@proxy.example.com:8080",
  browser: "chrome_142",
  poolMaxSize: 64,
});

try {
  const res = await fetch("https://httpbin.org/get", {
    transport,
    timeout: 10_000,
  });

  console.log(res.status);
} finally {
  await transport.close();
}

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Important: request options that become invalid

When you provide transport, you must not also set browser, os, proxy, or insecure on that request. Those settings are owned by the transport. Create one transport per proxy, reuse it for all requests that should go through that proxy, and close transports when you no longer need them. 
import { createTransport, fetch, type Transport } from "wreq-js";

const transports = new Map<string, Transport>();

async function getTransportForProxy(proxy: string): Promise<Transport> {
  const cached = transports.get(proxy);
  if (cached && !cached.closed) return cached;

  const transport = await createTransport({ proxy, poolMaxSize: 32 });
  transports.set(proxy, transport);
  return transport;
}

export async function fetchViaProxy(url: string, proxy: string) {
  const transport = await getTransportForProxy(proxy);
  return fetch(url, { transport, timeout: 30_000 });
}

export async function shutdown() {
  await Promise.all([...transports.values()].map((t) => t.close()));
  transports.clear();
}

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Transport lifecycle

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transport.close()

Always close transports you create. 
await transport.close();
After closing, transport.closed becomes true and the transport can no longer be used. If you need separate cookie jars with shared transport settings (for example, multiple sessions through the same proxy), you can pass the same transport to multiple Session.fetch() calls.