npm-registry-fetch

What is npm-registry-fetch?

The npm-registry-fetch package is a utility that provides a simple interface to fetch resources from the npm registry. It is designed to handle various aspects of communication with the npm registry, such as handling authentication, customizing requests, and processing responses. This package is particularly useful for developers who need to interact programmatically with the npm registry to fetch package data, publish updates, or perform other registry-related tasks.

What are npm-registry-fetch's main functionalities?

Fetching package metadata

This feature allows developers to fetch metadata about a package from the npm registry. The code sample demonstrates how to retrieve JSON data for the npm-registry-fetch package itself.

const fetch = require('npm-registry-fetch');
fetch.json('https://registry.npmjs.org/npm-registry-fetch').then(data => {
  console.log(data);
}).catch(err => {
  console.error('Error fetching package:', err);
});

Custom request options

This feature allows users to customize requests when interacting with the npm registry. The code sample shows how to set custom headers and request methods.

const fetch = require('npm-registry-fetch');
const opts = {
  method: 'GET',
  headers: {
    'Content-Type': 'application/json'
  }
};
fetch('https://registry.npmjs.org/npm-registry-fetch', opts).then(response => {
  return response.json();
}).then(data => {
  console.log(data);
}).catch(err => {
  console.error('Error with custom request:', err);
});

Other packages similar to npm-registry-fetch

request

The 'request' package is a simplified HTTP request client that supports numerous features for making HTTP calls. It is similar to npm-registry-fetch but is not specifically tailored for interacting with the npm registry. It offers broader HTTP request capabilities but lacks the specialized npm registry integration and convenience features that npm-registry-fetch provides.

axios

Axios is a promise-based HTTP client for the browser and node.js. Like npm-registry-fetch, it can be used to make HTTP requests to any URL, including the npm registry. However, axios is more general-purpose and does not include built-in configurations or optimizations specifically for the npm registry, unlike npm-registry-fetch which is optimized for such interactions.

README

npm-registry-fetch

npm-registry-fetch is a Node.js library that implements a fetch-like API for accessing npm registry APIs consistently. It's able to consume npm-style configuration values and has all the necessary logic for picking registries, handling scopes, and dealing with authentication details built-in.

This package is meant to replace the older npm-registry-client.

Example

const npmFetch = require('npm-registry-fetch')

console.log(
  await npmFetch.json('/-/ping')
)

Table of Contents

• Installing
• Example
• Contributing
• API
  • fetch
  • fetch.json
  • fetch options

Install

$ npm install npm-registry-fetch

Contributing

The npm team enthusiastically welcomes contributions and project participation! There's a bunch of things you can do if you want to contribute! The Contributor Guide has all the information you need for everything from reporting bugs to contributing entire new features. Please don't hesitate to jump in if you'd like to, or even ask us questions if something isn't clear.

All participants and maintainers in this project are expected to follow Code of Conduct, and just generally be excellent to each other.

Please refer to the Changelog for project history details, too.

Happy hacking!

API

Caching and write=true query strings

Before performing any PUT or DELETE operation, npm clients first make a GET request to the registry resource being updated, which includes the query string ?write=true.

The semantics of this are, effectively, "I intend to write to this thing, and need to know the latest current value, so that my write can land cleanly".

The public npm registry handles these ?write=true requests by ensuring that the cache is re-validated before sending a response. In order to maintain the same behavior on the client, and not get tripped up by an overeager local cache when we intend to write data to the registry, any request that comes through npm-registry-fetch that contains write=true in the query string will forcibly set the prefer-online option to true, and set both prefer-offline and offline to false, so that any local cached value will be revalidated.

> fetch(url, [opts]) -> Promise<Response>

Performs a request to a given URL.

The URL can be either a full URL, or a path to one. The appropriate registry will be automatically picked if only a URL path is given.

For available options, please see the section on fetch options.

Example

const res = await fetch('/-/ping')
console.log(res.headers)
res.on('data', d => console.log(d.toString('utf8')))

> fetch.json(url, [opts]) -> Promise<ResponseJSON>

Performs a request to a given registry URL, parses the body of the response as JSON, and returns it as its final value. This is a utility shorthand for fetch(url).then(res => res.json()).

For available options, please see the section on fetch options.

Example

const res = await fetch.json('/-/ping')
console.log(res) // Body parsed as JSON

> fetch.json.stream(url, jsonPath, [opts]) -> Stream

Performs a request to a given registry URL and parses the body of the response as JSON, with each entry being emitted through the stream.

The jsonPath argument is a JSONStream.parse() path, and the returned stream (unlike default JSONStreams), has a valid Symbol.asyncIterator implementation.

For available options, please see the section on fetch options.

Example

console.log('https://npm.im/~zkat has access to the following packages:')
for await (let {key, value} of fetch.json.stream('/-/user/zkat/package', '$*')) {
  console.log(`https://npm.im/${key} (perms: ${value})`)
}

fetch Options

Fetch options are optional, and can be passed in as either a Map-like object (one with a .get() method), a plain javascript object, or a figgy-pudding instance.

opts.agent

• Type: http.Agent
• Default: an appropriate agent based on URL protocol and proxy settings

An Agent instance to be shared across requests. This allows multiple concurrent fetch requests to happen on the same socket.

You do not need to provide this option unless you want something particularly specialized, since proxy configurations and http/https agents are already automatically managed internally when this option is not passed through.

opts.body

• Type: Buffer | Stream | Object
• Default: null

Request body to send through the outgoing request. Buffers and Streams will be passed through as-is, with a default content-type of application/octet-stream. Plain JavaScript objects will be JSON.stringifyed and the content-type will default to application/json.

Use opts.headers to set the content-type to something else.

opts.ca

• Type: String, Array, or null
• Default: null

The Certificate Authority signing certificate that is trusted for SSL connections to the registry. Values should be in PEM format (Windows calls it "Base-64 encoded X.509 (.CER)") with newlines replaced by the string '\n'. For example:

{
  ca: '-----BEGIN CERTIFICATE-----\nXXXX\nXXXX\n-----END CERTIFICATE-----'
}

Set to null to only allow "known" registrars, or to a specific CA cert to trust only that specific signing authority.

Multiple CAs can be trusted by specifying an array of certificates instead of a single string.

See also opts.strictSSL, opts.ca and opts.key

opts.cache

• Type: path
• Default: null

The location of the http cache directory. If provided, certain cachable requests will be cached according to IETF RFC 7234 rules. This will speed up future requests, as well as make the cached data available offline if necessary/requested.

See also offline, preferOffline, and preferOnline.

opts.cert

• Type: String
• Default: null

A client certificate to pass when accessing the registry. Values should be in PEM format (Windows calls it "Base-64 encoded X.509 (.CER)") with newlines replaced by the string '\n'. For example:

{
  cert: '-----BEGIN CERTIFICATE-----\nXXXX\nXXXX\n-----END CERTIFICATE-----'
}

It is not the path to a certificate file (and there is no "certfile" option).

See also: opts.ca and opts.key

opts.fetchRetries

• Type: Number
• Default: 2

The "retries" config for retry to use when fetching packages from the registry.

See also opts.retry to provide all retry options as a single object.

opts.fetchRetryFactor

• Type: Number
• Default: 10

The "factor" config for retry to use when fetching packages.

See also opts.retry to provide all retry options as a single object.

opts.fetchRetryMintimeout

• Type: Number
• Default: 10000 (10 seconds)

The "minTimeout" config for retry to use when fetching packages.

See also opts.retry to provide all retry options as a single object.

opts.fetchRetryMaxtimeout

• Type: Number
• Default: 60000 (1 minute)

The "maxTimeout" config for retry to use when fetching packages.

See also opts.retry to provide all retry options as a single object.

opts.forceAuth

• Type: Object
• Default: null

If present, other auth-related values in opts will be completely ignored, including alwaysAuth, email, and otp, when calculating auth for a request, and the auth details in opts.forceAuth will be used instead.

opts.gzip

• Type: Boolean
• Default: false

If true, npm-registry-fetch will set the Content-Encoding header to gzip and use zlib.gzip() or zlib.createGzip() to gzip-encode opts.body.

opts.headers

• Type: Object
• Default: null

Additional headers for the outgoing request. This option can also be used to override headers automatically generated by npm-registry-fetch, such as Content-Type.

opts.ignoreBody

• Type: Boolean
• Default: false

If true, the response body will be thrown away and res.body set to null. This will prevent dangling response sockets for requests where you don't usually care what the response body is.

opts.integrity

• Type: String | SRI object
• Default: null

If provided, the response body's will be verified against this integrity string, using ssri. If verification succeeds, the response will complete as normal. If verification fails, the response body will error with an EINTEGRITY error.

Body integrity is only verified if the body is actually consumed to completion -- that is, if you use res.json()/res.buffer(), or if you consume the default res stream data to its end.

Cached data will have its integrity automatically verified using the previously-generated integrity hash for the saved request information, so EINTEGRITY errors can happen if opts.cache is used, even if opts.integrity is not passed in.

opts.key

• Type: String
• Default: null

A client key to pass when accessing the registry. Values should be in PEM format with newlines replaced by the string '\n'. For example:

{
  key: '-----BEGIN PRIVATE KEY-----\nXXXX\nXXXX\n-----END PRIVATE KEY-----'
}

It is not the path to a key file (and there is no "keyfile" option).

See also: opts.ca and opts.cert

opts.localAddress

• Type: IP Address String
• Default: null

The IP address of the local interface to use when making connections to the registry.

See also opts.proxy

opts.mapJSON

• Type: Function
• Default: undefined

When using fetch.json.stream() (NOT fetch.json()), this will be passed down to JSONStream as the second argument to JSONStream.parse, and can be used to transform stream data before output.

opts.maxSockets

• Type: Integer
• Default: 12

Maximum number of sockets to keep open during requests. Has no effect if opts.agent is used.

opts.method

• Type: String
• Default: 'GET'

HTTP method to use for the outgoing request. Case-insensitive.

opts.noProxy

• Type: String | String[]
• Default: process.env.NOPROXY

If present, should be a comma-separated string or an array of domain extensions that a proxy should not be used for.

opts.npmSession

• Type: String
• Default: null

If provided, will be sent in the npm-session header. This header is used by the npm registry to identify individual user sessions (usually individual invocations of the CLI).

opts.npmCommand

• Type: String
• Default: null

If provided, it will be sent in the npm-command header. This header is used by the npm registry to identify the npm command that caused this request to be made.

opts.offline

• Type: Boolean
• Default: false

Force offline mode: no network requests will be done during install. To allow npm-registry-fetch to fill in missing cache data, see opts.preferOffline.

This option is only really useful if you're also using opts.cache.

This option is set to true when the request includes write=true in the query string.

opts.otp

• Type: Number | String
• Default: null

This is a one-time password from a two-factor authenticator. It is required for certain registry interactions when two-factor auth is enabled for a user account.

opts.otpPrompt

• Type: Function
• Default: null

This is a method which will be called to provide an OTP if the server responds with a 401 response indicating that a one-time-password is required.

It may return a promise, which must resolve to the OTP value to be used. If the method fails to provide an OTP value, then the fetch will fail with the auth error that indicated an OTP was needed.

opts.password

• Alias: _password
• Type: String
• Default: null

Password used for basic authentication. For the more modern authentication method, please use the (more secure) opts.token

Can optionally be scoped to a registry by using a "nerf dart" for that registry. That is:

{
  '//registry.npmjs.org/:password': 't0k3nH34r'
}

See also opts.username

opts.preferOffline

• Type: Boolean
• Default: false

If true, staleness checks for cached data will be bypassed, but missing data will be requested from the server. To force full offline mode, use opts.offline.

This option is generally only useful if you're also using opts.cache.

This option is set to false when the request includes write=true in the query string.

opts.preferOnline

• Type: Boolean
• Default: false

If true, staleness checks for cached data will be forced, making the CLI look for updates immediately even for fresh package data.

This option is generally only useful if you're also using opts.cache.

This option is set to true when the request includes write=true in the query string.

opts.scope

• Type: String
• Default: null

If provided, will be sent in the npm-scope header. This header is used by the npm registry to identify the toplevel package scope that a particular project installation is using.

opts.proxy

• Type: url
• Default: null

A proxy to use for outgoing http requests. If not passed in, the HTTP(S)_PROXY environment variable will be used.

opts.query

• Type: String | Object
• Default: null

If provided, the request URI will have a query string appended to it using this query. If opts.query is an object, it will be converted to a query string using querystring.stringify().

If the request URI already has a query string, it will be merged with opts.query, preferring opts.query values.

opts.registry

• Type: URL
• Default: 'https://registry.npmjs.org'

Registry configuration for a request. If a request URL only includes the URL path, this registry setting will be prepended.

See also opts.scope, opts.spec, and opts.<scope>:registry which can all affect the actual registry URL used by the outgoing request.

opts.retry

• Type: Object
• Default: null

Single-object configuration for request retry settings. If passed in, will override individually-passed fetch-retry-* settings.

opts.scope

• Type: String
• Default: null

Associate an operation with a scope for a scoped registry. This option can force lookup of scope-specific registries and authentication.

See also opts.<scope>:registry and opts.spec for interactions with this option.

opts.<scope>:registry

• Type: String
• Default: null

This option type can be used to configure the registry used for requests involving a particular scope. For example, opts['@myscope:registry'] = 'https://scope-specific.registry/' will make it so requests go out to this registry instead of opts.registry when opts.scope is used, or when opts.spec is a scoped package spec.

The @ before the scope name is optional, but recommended.

opts.spec

• Type: String | npm-registry-arg object.
• Default: null

If provided, can be used to automatically configure opts.scope based on a specific package name. Non-registry package specs will throw an error.

opts.strictSSL

• Type: Boolean
• Default: true

Whether or not to do SSL key validation when making requests to the registry via https.

See also opts.ca.

opts.timeout

• Type: Milliseconds
• Default: 300000 (5 minutes)

Time before a hanging request times out.

opts._authToken

• Type: String
• Default: null

Authentication token string.

Can be scoped to a registry by using a "nerf dart" for that registry. That is:

{
  '//registry.npmjs.org/:_authToken': 't0k3nH34r'
}

opts.userAgent

• Type: String
• Default: 'npm-registry-fetch@<version>/node@<node-version>+<arch> (<platform>)'

User agent string to send in the User-Agent header.

opts.username

• Type: String
• Default: null

Username used for basic authentication. For the more modern authentication method, please use the (more secure) opts.authtoken

Can optionally be scoped to a registry by using a "nerf dart" for that registry. That is:

{
  '//registry.npmjs.org/:username': 't0k3nH34r'
}

See also opts.password

Changelog

18.0.2 (2024-10-16)

Bug Fixes

• 8044781 #273 log cache hits distinct from fetch (#273) (@mbtools)

Chores

• 99b99d2 #269 bump cacache from 18.0.4 to 19.0.1 (#269) (@dependabot[bot])
• bd3f7d1 #272 bump @npmcli/template-oss from 4.23.3 to 4.23.4 (#272) (@dependabot[bot], @npm-cli-bot)