@nxtedition/undici

undici

An HTTP/1.1 client, written from scratch for Node.js.

Undici means eleven in Italian. 1.1 -> 11 -> Eleven -> Undici. It is also a Stranger Things reference.

How to get involved

Have a question about using Undici? Open a Q&A Discussion or join our official OpenJS Slack channel.

Looking to contribute? Start by reading the contributing guide

Install

npm i undici

Benchmarks

The benchmark is a simple getting data example using a 50 TCP connections with a pipelining depth of 10 running on Node 20.10.0.

Tests	Samples	Result	Tolerance	Difference with slowest
undici - fetch	30	3704.43 req/sec	± 2.95 %	-
http - no keepalive	20	4275.30 req/sec	± 2.60 %	+ 15.41 %
node-fetch	10	4759.42 req/sec	± 0.87 %	+ 28.48 %
request	40	4803.37 req/sec	± 2.77 %	+ 29.67 %
axios	45	4951.97 req/sec	± 2.88 %	+ 33.68 %
got	10	5969.67 req/sec	± 2.64 %	+ 61.15 %
superagent	10	9471.48 req/sec	± 1.50 %	+ 155.68 %
http - keepalive	25	10327.49 req/sec	± 2.95 %	+ 178.79 %
undici - pipeline	10	15053.41 req/sec	± 1.63 %	+ 306.36 %
undici - request	10	19264.24 req/sec	± 1.74 %	+ 420.03 %
undici - stream	15	20317.29 req/sec	± 2.13 %	+ 448.46 %
undici - dispatch	10	24883.28 req/sec	± 1.54 %	+ 571.72 %

The benchmark is a simple sending data example using a 50 TCP connections with a pipelining depth of 10 running on Node 20.10.0.

Tests	Samples	Result	Tolerance	Difference with slowest
undici - fetch	20	1968.42 req/sec	± 2.63 %	-
http - no keepalive	25	2330.30 req/sec	± 2.99 %	+ 18.38 %
node-fetch	20	2485.36 req/sec	± 2.70 %	+ 26.26 %
got	15	2787.68 req/sec	± 2.56 %	+ 41.62 %
request	30	2805.10 req/sec	± 2.59 %	+ 42.50 %
axios	10	3040.45 req/sec	± 1.72 %	+ 54.46 %
superagent	20	3358.29 req/sec	± 2.51 %	+ 70.61 %
http - keepalive	20	3477.94 req/sec	± 2.51 %	+ 76.69 %
undici - pipeline	25	3812.61 req/sec	± 2.80 %	+ 93.69 %
undici - request	10	6067.00 req/sec	± 0.94 %	+ 208.22 %
undici - stream	10	6391.61 req/sec	± 1.98 %	+ 224.71 %
undici - dispatch	10	6397.00 req/sec	± 1.48 %	+ 224.98 %

Quick Start

import { request } from 'undici'

const {
  statusCode,
  headers,
  trailers,
  body
} = await request('http://localhost:3000/foo')

console.log('response received', statusCode)
console.log('headers', headers)

for await (const data of body) { console.log('data', data) }

console.log('trailers', trailers)

Body Mixins

The body mixins are the most common way to format the request/response body. Mixins include:

• .arrayBuffer()
• .blob()
• .json()
• .text()

[!NOTE] The body returned from undici.request does not implement .formData().

Example usage:

import { request } from 'undici'

const {
  statusCode,
  headers,
  trailers,
  body
} = await request('http://localhost:3000/foo')

console.log('response received', statusCode)
console.log('headers', headers)
console.log('data', await body.json())
console.log('trailers', trailers)

Note: Once a mixin has been called then the body cannot be reused, thus calling additional mixins on .body, e.g. .body.json(); .body.text() will result in an error TypeError: unusable being thrown and returned through the Promise rejection.

Should you need to access the body in plain-text after using a mixin, the best practice is to use the .text() mixin first and then manually parse the text to the desired format.

For more information about their behavior, please reference the body mixin from the Fetch Standard.

undici.request([url, options]): Promise

Arguments:

• url string | URL | UrlObject
• options RequestOptions
  • dispatcher Dispatcher - Default: getGlobalDispatcher
  • method String - Default: PUT if options.body, otherwise GET
  • maxRedirections Integer - Default: 0

Returns a promise with the result of the Dispatcher.request method.

Calls options.dispatcher.request(options).

See Dispatcher.request for more details, and request examples for examples.

undici.setGlobalDispatcher(dispatcher)

• dispatcher Dispatcher

Sets the global dispatcher used by Common API Methods.

undici.getGlobalDispatcher()

Gets the global dispatcher used by Common API Methods.

Returns: Dispatcher

UrlObject

• port string | number (optional)
• path string (optional)
• pathname string (optional)
• hostname string (optional)
• origin string (optional)
• protocol string (optional)
• search string (optional)

Specification Compliance

This section documents parts of the HTTP/1.1 specification that Undici does not support or does not fully implement.

Expect

Undici does not support the Expect request header field. The request body is always immediately sent and the 100 Continue response will be ignored.

Refs: https://tools.ietf.org/html/rfc7231#section-5.1.1

Pipelining

Undici will only use pipelining if configured with a pipelining factor greater than 1.

Undici always assumes that connections are persistent and will immediately pipeline requests, without checking whether the connection is persistent. Hence, automatic fallback to HTTP/1.0 or HTTP/1.1 without pipelining is not supported.

Undici will immediately pipeline when retrying requests after a failed connection. However, Undici will not retry the first remaining requests in the prior pipeline and instead error the corresponding callback/promise/stream.

Undici will abort all running requests in the pipeline when any of them are aborted.

• Refs: https://tools.ietf.org/html/rfc2616#section-8.1.2.2
• Refs: https://tools.ietf.org/html/rfc7230#section-6.3.2

Manual Redirect

Since it is not possible to manually follow an HTTP redirect on the server-side, Undici returns the actual response instead of an opaqueredirect filtered one when invoked with a manual redirect. This aligns fetch() with the other implementations in Deno and Cloudflare Workers.

Refs: https://fetch.spec.whatwg.org/#atomic-http-redirect-handling

Workarounds

Network address family autoselection.

If you experience problem when connecting to a remote server that is resolved by your DNS servers to a IPv6 (AAAA record) first, there are chances that your local router or ISP might have problem connecting to IPv6 networks. In that case undici will throw an error with code UND_ERR_CONNECT_TIMEOUT.

If the target server resolves to both a IPv6 and IPv4 (A records) address and you are using a compatible Node version (18.3.0 and above), you can fix the problem by providing the autoSelectFamily option (support by both undici.request and undici.Agent) which will enable the family autoselection algorithm when establishing the connection.

Collaborators

• Daniele Belardi, https://www.npmjs.com/~dnlup
• Ethan Arrowood, https://www.npmjs.com/~ethan_arrowood
• Matteo Collina, https://www.npmjs.com/~matteo.collina
• Matthew Aitken, https://www.npmjs.com/~khaf
• Robert Nagy, https://www.npmjs.com/~ronag
• Szymon Marczak, https://www.npmjs.com/~szmarczak
• Tomas Della Vedova, https://www.npmjs.com/~delvedor

Releasers

• Ethan Arrowood, https://www.npmjs.com/~ethan_arrowood
• Matteo Collina, https://www.npmjs.com/~matteo.collina
• Robert Nagy, https://www.npmjs.com/~ronag
• Matthew Aitken, https://www.npmjs.com/~khaf

License

MIT