The undici npm package is a HTTP/1.1 client, written from scratch for Node.js, that is designed to be faster and more efficient than the built-in 'http' and 'https' modules. It provides a low-level API for making HTTP requests and can be used to build higher-level abstractions.
HTTP Request
Make an HTTP request and process the response. This is the basic functionality of undici, allowing you to send HTTP requests and receive responses.
const { request } = require('undici');
(async () => {
const { statusCode, headers, body } = await request('https://example.com')
console.log('response received', statusCode);
for await (const data of body) {
console.log('data', data);
}
})();HTTP Pool
Use a pool of connections to make HTTP requests. This is useful for making a large number of requests to the same server, as it reuses connections between requests.
const { Pool } = require('undici');
const pool = new Pool('https://example.com')
async function query() {
const { body } = await pool.request({
path: '/path',
method: 'GET'
})
for await (const data of body) {
console.log('data', data);
}
}
query();HTTP Stream
Stream an HTTP response to a file or another stream. This is useful for handling large responses that you don't want to hold in memory.
const { pipeline } = require('undici');
const fs = require('fs');
pipeline(
'https://example.com',
fs.createWriteStream('output.txt'),
(err) => {
if (err) {
console.error('Pipeline failed', err);
} else {
console.log('Pipeline succeeded');
}
}
);HTTP Upgrade
Upgrade an HTTP connection to another protocol, such as WebSockets. This is useful for protocols that start with an HTTP handshake and then upgrade to a different protocol.
const { connect } = require('undici');
(async () => {
const { socket, statusCode, headers } = await connect({
path: '/path',
method: 'GET'
});
console.log('upgrade response', statusCode, headers);
socket.on('data', (chunk) => {
console.log('data', chunk.toString());
});
})();Axios is a promise-based HTTP client for the browser and Node.js. It provides a simple API for making HTTP requests and is often used for its ease of use and wide adoption. Compared to undici, axios is higher-level and more feature-rich, but may not be as performant for certain use cases.
Got is a human-friendly and powerful HTTP request library for Node.js. It supports streams, promises, and provides a rich set of features for making HTTP requests. Got is similar to undici in terms of performance but offers a more comprehensive API surface.
node-fetch is a light-weight module that brings the Fetch API to Node.js. It is designed to mimic the browser fetch API as closely as possible. While undici focuses on HTTP/1.1, node-fetch provides a familiar interface for those used to working with fetch in the browser.
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://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.
undici.request(url[, options]): PromiseArguments:
string | URL | objectRequestOptions
Dispatcher - Default: getGlobalDispatcherString - Default: GETInteger - Default: 0Returns 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.
undici.stream(url, options, factory): PromiseArguments:
string | URL | objectStreamOptions
Dispatcher - Default: getGlobalDispatcherString - Default: GETDispatcher.stream.factoryReturns 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.
undici.pipeline(url, options, handler): DuplexArguments:
string | URL | objectPipelineOptions
Dispatcher - Default: getGlobalDispatcherString - Default: GETDispatcher.pipeline.handlerReturns: stream.Duplex
url may contain pathname. options may not contain path.
Calls options.dispatch.pipeline(options, handler).
See Dispatcher.pipeline for more details.
undici.connect(options[, callback])Starts two-way communications with the requested resource using HTTP CONNECT.
Arguments:
ConnectOptions
Dispatcher - Default: getGlobalDispatcherString - Default: GET(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.
undici.upgrade(options[, callback])Upgrade to a different protocol. See MDN - HTTP - Protocol upgrade mechanism for more details.
Arguments:
UpgradeOptions
Dispatcher - Default: getGlobalDispatcherString - Default: GET(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.
undici.setGlobalDispatcher(dispatcher)DispatcherSets the global dispatcher used by global API methods.
undici.getGlobalDispatcher()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.
MIT
FAQs
An HTTP/1.1 client, written from scratch for Node.js
The npm package undici receives a total of 8,061,172 weekly downloads. As such, undici popularity was classified as popular.
We found that undici demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 3 open source maintainers collaborating on the project.
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