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.

npm i undici

Machine: AMD EPYC 7502P

Node 15

http - keepalive x 12,028 ops/sec ±2.60% (265 runs sampled)
undici - pipeline x 31,321 ops/sec ±0.77% (276 runs sampled)
undici - request x 36,612 ops/sec ±0.71% (277 runs sampled)
undici - stream x 41,291 ops/sec ±0.90% (268 runs sampled)
undici - dispatch x 47,319 ops/sec ±1.17% (263 runs sampled)

The benchmark is a simple hello world example using a single unix socket with pipelining.

import { request } from 'undici'

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

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.

Arguments:

• url string | URL | object
• options RequestOptions
  • dispatcher Dispatcher - Default: getGlobalDispatcher
  • method String - Default: GET
  • maxRedirections Integer - Default: 0

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

url may contain pathname. options may not contain path.

Calls options.dispatcher.request(options).

See Dispatcher.request for more details.

Arguments:

• url string | URL | object
• options StreamOptions
  • dispatcher Dispatcher - Default: getGlobalDispatcher
  • method String - Default: GET
• factory Dispatcher.stream.factory

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

url may contain pathname. options may not contain path.

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

See Dispatcher.stream for more details.

Arguments:

• url string | URL | object
• options PipelineOptions
  • dispatcher Dispatcher - Default: getGlobalDispatcher
  • method String - Default: GET
• handler Dispatcher.pipeline.handler

Returns: stream.Duplex

url may contain pathname. options may not contain path.

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

See Dispatcher.pipeline for more details.

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

Arguments:

• options ConnectOptions
  • dispatcher Dispatcher - Default: getGlobalDispatcher
  • method String - Default: GET
• callback (err: Error | null, data: ConnectData | null) => void (optional)

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

url may contain pathname. options may not contain path.

Calls options.dispatch.connect(options).

See Dispatcher.connect for more details.

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

Arguments:

• options UpgradeOptions
  • dispatcher Dispatcher - Default: getGlobalDispatcher
  • method String - Default: GET
• callback (error: Error | null, data: UpgradeData) => void (optional)

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

url may contain pathname. options may not contain path.

Calls options.dispatcher.upgrade(options).

See Dispatcher.upgrade for more details.

• dispatcher Dispatcher

Sets the global dispatcher used by global API methods.

Gets the global dispatcher used by global API methods.

Returns: Dispatcher

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

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

Uncidi 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

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

MIT