undici

A 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.

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

Install

npm i undici

Benchmarks

The benchmark is a simple hello world example using a number of unix sockets (connections) with a pipelining depth of 10 running on Node 16. The benchmarks below have the simd feature enabled.

Connections 1

Tests	Samples	Result	Tolerance	Difference with slowest
http - no keepalive	15	4.63 req/sec	± 2.77 %	-
http - keepalive	10	4.81 req/sec	± 2.16 %	+ 3.94 %
undici - stream	25	62.22 req/sec	± 2.67 %	+ 1244.58 %
undici - dispatch	15	64.33 req/sec	± 2.47 %	+ 1290.24 %
undici - request	15	66.08 req/sec	± 2.48 %	+ 1327.88 %
undici - pipeline	10	66.13 req/sec	± 1.39 %	+ 1329.08 %

Connections 50

Tests	Samples	Result	Tolerance	Difference with slowest
http - no keepalive	50	3546.49 req/sec	± 2.90 %	-
http - keepalive	15	5692.67 req/sec	± 2.48 %	+ 60.52 %
undici - pipeline	25	8478.71 req/sec	± 2.62 %	+ 139.07 %
undici - request	20	9766.66 req/sec	± 2.79 %	+ 175.39 %
undici - stream	15	10109.74 req/sec	± 2.94 %	+ 185.06 %
undici - dispatch	25	10949.73 req/sec	± 2.54 %	+ 208.75 %

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)

Using the body mixin from the Fetch Standard.

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)

Common API Methods

This section documents our most commonly used API methods. Additional APIs are documented in their own files within the docs folder and are accessible via the navigation list on the left side of the docs site.

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

Arguments:

• url string | URL | object
• 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.

undici.stream([url, options, ]factory): Promise

Arguments:

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

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

Calls options.dispatcher.stream(options, factory).

See Dispatcher.stream for more details.

undici.pipeline([url, options, ]handler): Duplex

Arguments:

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

Returns: stream.Duplex

Calls options.dispatch.pipeline(options, handler).

See Dispatcher.pipeline for more details.

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

Starts two-way communications with the requested resource using HTTP CONNECT.

Arguments:

• url string | URL | object
• options ConnectOptions
  • dispatcher Dispatcher - Default: getGlobalDispatcher
  • maxRedirections Integer - Default: 0
• callback (err: Error | null, data: ConnectData | null) => void (optional)

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

Calls options.dispatch.connect(options).

See Dispatcher.connect for more details.

https://fetch.spec.whatwg.org/

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

Implements fetch.

Only supported on Node 16+.

This is experimental and is not yet fully compliant the Fetch Standard. We plan to ship breaking changes to this feature until it is out of experimental.

Arguments:

• url string | URL | object
• options RequestInit

Returns: Promise<Response>

Parameter: RequestInit

https://fetch.spec.whatwg.org/#request-class

• method string
• headers HeadersInit
• body BodyInit?
• referrer not supported
• referrerPolicy not supported
• mode not supported
• credentials not supported
• cache not supported
• redirect RequestRedirect
• integrity not supported
• keepalive not supported
• signal AbortSignal?
• window null

Parameter: Response

https://fetch.spec.whatwg.org/#response-class

• type ResponseType
• url string
• redirected boolean
• status number
• ok boolean
• statusText string
• headers Headers

See Dispatcher.fetch for more details.

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

Upgrade to a different protocol. See MDN - HTTP - Protocol upgrade mechanism for more details.

Arguments:

• url string | URL | object
• options UpgradeOptions
  • dispatcher Dispatcher - Default: getGlobalDispatcher
  • maxRedirections Integer - Default: 0
• callback (error: Error | null, data: UpgradeData) => void (optional)

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

Calls options.dispatcher.upgrade(options).

See Dispatcher.upgrade for more details.

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

Specification Compliance

This section documents parts of the HTTP/1.1 specification which 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 afters 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

Collaborators

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

Releasers

• Matteo Collina, https://www.npmjs.com/~matteo.collina
• Robert Nagy, https://www.npmjs.com/~ronag

License

MIT