361 lines
15 KiB
Markdown
361 lines
15 KiB
Markdown
# make-fetch-happen
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[](https://npm.im/make-fetch-happen) [](https://npm.im/make-fetch-happen) [](https://travis-ci.org/npm/make-fetch-happen) [](https://coveralls.io/github/npm/make-fetch-happen?branch=latest)
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[`make-fetch-happen`](https://github.com/npm/make-fetch-happen) is a Node.js
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library that wraps [`minipass-fetch`](https://github.com/npm/minipass-fetch) with additional
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features [`minipass-fetch`](https://github.com/npm/minipass-fetch) doesn't intend to include, including HTTP Cache support, request
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pooling, proxies, retries, [and more](#features)!
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## Install
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`$ npm install --save make-fetch-happen`
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## Table of Contents
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* [Example](#example)
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* [Features](#features)
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* [Contributing](#contributing)
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* [API](#api)
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* [`fetch`](#fetch)
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* [`fetch.defaults`](#fetch-defaults)
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* [`minipass-fetch` options](#minipass-fetch-options)
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* [`make-fetch-happen` options](#extra-options)
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* [`opts.cachePath`](#opts-cache-path)
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* [`opts.cache`](#opts-cache)
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* [`opts.proxy`](#opts-proxy)
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* [`opts.noProxy`](#opts-no-proxy)
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* [`opts.ca, opts.cert, opts.key`](#https-opts)
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* [`opts.maxSockets`](#opts-max-sockets)
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* [`opts.retry`](#opts-retry)
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* [`opts.onRetry`](#opts-onretry)
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* [`opts.integrity`](#opts-integrity)
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* [`opts.dns`](#opts-dns)
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* [Message From Our Sponsors](#wow)
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### Example
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```javascript
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const fetch = require('make-fetch-happen').defaults({
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cachePath: './my-cache' // path where cache will be written (and read)
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})
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fetch('https://registry.npmjs.org/make-fetch-happen').then(res => {
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return res.json() // download the body as JSON
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}).then(body => {
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console.log(`got ${body.name} from web`)
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return fetch('https://registry.npmjs.org/make-fetch-happen', {
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cache: 'no-cache' // forces a conditional request
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})
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}).then(res => {
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console.log(res.status) // 304! cache validated!
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return res.json().then(body => {
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console.log(`got ${body.name} from cache`)
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})
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})
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```
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### Features
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* Builds around [`minipass-fetch`](https://npm.im/minipass-fetch) for the core [`fetch` API](https://fetch.spec.whatwg.org) implementation
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* Request pooling out of the box
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* Quite fast, really
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* Automatic HTTP-semantics-aware request retries
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* Cache-fallback automatic "offline mode"
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* Proxy support (http, https, socks, socks4, socks5)
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* Built-in request caching following full HTTP caching rules (`Cache-Control`, `ETag`, `304`s, cache fallback on error, etc).
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* Node.js Stream support
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* Transparent gzip and deflate support
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* [Subresource Integrity](https://developer.mozilla.org/en-US/docs/Web/Security/Subresource_Integrity) support
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* Literally punches nazis
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* Built in DNS cache
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* (PENDING) Range request caching and resuming
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### Contributing
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The make-fetch-happen team enthusiastically welcomes contributions and project participation! There's a bunch of things you can do if you want to contribute! The [Contributor Guide](https://github.com/npm/cli/blob/latest/CONTRIBUTING.md) outlines the process for community interaction and contribution. Please don't hesitate to jump in if you'd like to, or even ask us questions if something isn't clear.
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All participants and maintainers in this project are expected to follow the [npm Code of Conduct](https://www.npmjs.com/policies/conduct), and just generally be excellent to each other.
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Please refer to the [Changelog](CHANGELOG.md) for project history details, too.
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Happy hacking!
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### API
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#### <a name="fetch"></a> `> fetch(uriOrRequest, [opts]) -> Promise<Response>`
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This function implements most of the [`fetch` API](https://developer.mozilla.org/en-US/docs/Web/API/WindowOrWorkerGlobalScope/fetch): given a `uri` string or a `Request` instance, it will fire off an http request and return a Promise containing the relevant response.
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If `opts` is provided, the [`minipass-fetch`-specific options](#minipass-fetch-options) will be passed to that library. There are also [additional options](#extra-options) specific to make-fetch-happen that add various features, such as HTTP caching, integrity verification, proxy support, and more.
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##### Example
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```javascript
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fetch('https://google.com').then(res => res.buffer())
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```
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#### <a name="fetch-defaults"></a> `> fetch.defaults([defaultUrl], [defaultOpts])`
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Returns a new `fetch` function that will call `make-fetch-happen` using `defaultUrl` and `defaultOpts` as default values to any calls.
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A defaulted `fetch` will also have a `.defaults()` method, so they can be chained.
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##### Example
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```javascript
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const fetch = require('make-fetch-happen').defaults({
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cachePath: './my-local-cache'
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})
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fetch('https://registry.npmjs.org/make-fetch-happen') // will always use the cache
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```
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#### <a name="minipass-fetch-options"></a> `> minipass-fetch options`
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The following options for `minipass-fetch` are used as-is:
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* method
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* body
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* redirect
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* follow
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* timeout
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* compress
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* size
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These other options are modified or augmented by make-fetch-happen:
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* headers - Default `User-Agent` set to make-fetch happen. `Connection` is set to `keep-alive` or `close` automatically depending on `opts.agent`.
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* agent
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* If agent is null, an http or https Agent will be automatically used. By default, these will be `http.globalAgent` and `https.globalAgent`.
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* If [`opts.proxy`](#opts-proxy) is provided and `opts.agent` is null, the agent will be set to an appropriate proxy-handling agent.
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* If `opts.agent` is an object, it will be used as the request-pooling agent argument for this request.
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* If `opts.agent` is `false`, it will be passed as-is to the underlying request library. This causes a new Agent to be spawned for every request.
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For more details, see [the documentation for `minipass-fetch` itself](https://github.com/npm/minipass-fetch#options).
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#### <a name="extra-options"></a> `> make-fetch-happen options`
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make-fetch-happen augments the `minipass-fetch` API with additional features available through extra options. The following extra options are available:
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* [`opts.cachePath`](#opts-cache-path) - Cache target to read/write
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* [`opts.cache`](#opts-cache) - `fetch` cache mode. Controls cache *behavior*.
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* [`opts.proxy`](#opts-proxy) - Proxy agent
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* [`opts.noProxy`](#opts-no-proxy) - Domain segments to disable proxying for.
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* [`opts.ca, opts.cert, opts.key, opts.strictSSL`](#https-opts)
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* [`opts.localAddress`](#opts-local-address)
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* [`opts.maxSockets`](#opts-max-sockets)
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* [`opts.retry`](#opts-retry) - Request retry settings
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* [`opts.onRetry`](#opts-onretry) - a function called whenever a retry is attempted
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* [`opts.integrity`](#opts-integrity) - [Subresource Integrity](https://developer.mozilla.org/en-US/docs/Web/Security/Subresource_Integrity) metadata.
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* [`opts.dns`](#opts-dns) - DNS cache options
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#### <a name="opts-cache-path"></a> `> opts.cachePath`
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A string `Path` to be used as the cache root for [`cacache`](https://npm.im/cacache).
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**NOTE**: Requests will not be cached unless their response bodies are consumed. You will need to use one of the `res.json()`, `res.buffer()`, etc methods on the response, or drain the `res.body` stream, in order for it to be written.
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The default cache manager also adds the following headers to cached responses:
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* `X-Local-Cache`: Path to the cache the content was found in
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* `X-Local-Cache-Key`: Unique cache entry key for this response
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* `X-Local-Cache-Mode`: Always `stream` to indicate how the response was read from cacache
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* `X-Local-Cache-Hash`: Specific integrity hash for the cached entry
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* `X-Local-Cache-Status`: One of `miss`, `hit`, `stale`, `revalidated`, `updated`, or `skip` to signal how the response was created
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* `X-Local-Cache-Time`: UTCString of the cache insertion time for the entry
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Using [`cacache`](https://npm.im/cacache), a call like this may be used to
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manually fetch the cached entry:
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```javascript
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const h = response.headers
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cacache.get(h.get('x-local-cache'), h.get('x-local-cache-key'))
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// grab content only, directly:
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cacache.get.byDigest(h.get('x-local-cache'), h.get('x-local-cache-hash'))
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```
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##### Example
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```javascript
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fetch('https://registry.npmjs.org/make-fetch-happen', {
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cachePath: './my-local-cache'
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}) // -> 200-level response will be written to disk
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```
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#### <a name="opts-cache"></a> `> opts.cache`
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This option follows the standard `fetch` API cache option. This option will do nothing if [`opts.cachePath`](#opts-cache-path) is null. The following values are accepted (as strings):
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* `default` - Fetch will inspect the HTTP cache on the way to the network. If there is a fresh response it will be used. If there is a stale response a conditional request will be created, and a normal request otherwise. It then updates the HTTP cache with the response. If the revalidation request fails (for example, on a 500 or if you're offline), the stale response will be returned.
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* `no-store` - Fetch behaves as if there is no HTTP cache at all.
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* `reload` - Fetch behaves as if there is no HTTP cache on the way to the network. Ergo, it creates a normal request and updates the HTTP cache with the response.
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* `no-cache` - Fetch creates a conditional request if there is a response in the HTTP cache and a normal request otherwise. It then updates the HTTP cache with the response.
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* `force-cache` - Fetch uses any response in the HTTP cache matching the request, not paying attention to staleness. If there was no response, it creates a normal request and updates the HTTP cache with the response.
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* `only-if-cached` - Fetch uses any response in the HTTP cache matching the request, not paying attention to staleness. If there was no response, it returns a network error. (Can only be used when request’s mode is "same-origin". Any cached redirects will be followed assuming request’s redirect mode is "follow" and the redirects do not violate request’s mode.)
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(Note: option descriptions are taken from https://fetch.spec.whatwg.org/#http-network-or-cache-fetch)
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##### Example
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```javascript
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const fetch = require('make-fetch-happen').defaults({
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cachePath: './my-cache'
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})
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// Will error with ENOTCACHED if we haven't already cached this url
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fetch('https://registry.npmjs.org/make-fetch-happen', {
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cache: 'only-if-cached'
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})
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// Will refresh any local content and cache the new response
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fetch('https://registry.npmjs.org/make-fetch-happen', {
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cache: 'reload'
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})
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// Will use any local data, even if stale. Otherwise, will hit network.
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fetch('https://registry.npmjs.org/make-fetch-happen', {
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cache: 'force-cache'
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})
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```
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#### <a name="opts-proxy"></a> `> opts.proxy`
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A string or `new url.URL()`-d URI to proxy through. Different Proxy handlers will be
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used depending on the proxy's protocol.
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Additionally, `process.env.HTTP_PROXY`, `process.env.HTTPS_PROXY`, and
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`process.env.PROXY` are used if present and no `opts.proxy` value is provided.
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(Pending) `process.env.NO_PROXY` may also be configured to skip proxying requests for all, or specific domains.
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##### Example
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```javascript
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fetch('https://registry.npmjs.org/make-fetch-happen', {
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proxy: 'https://corporate.yourcompany.proxy:4445'
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})
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fetch('https://registry.npmjs.org/make-fetch-happen', {
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proxy: {
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protocol: 'https:',
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hostname: 'corporate.yourcompany.proxy',
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port: 4445
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}
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})
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```
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#### <a name="opts-no-proxy"></a> `> opts.noProxy`
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If present, should be a comma-separated string or an array of domain extensions
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that a proxy should _not_ be used for.
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This option may also be provided through `process.env.NO_PROXY`.
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#### <a name="https-opts"></a> `> opts.ca, opts.cert, opts.key, opts.strictSSL`
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These values are passed in directly to the HTTPS agent and will be used for both
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proxied and unproxied outgoing HTTPS requests. They mostly correspond to the
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same options the `https` module accepts, which will be themselves passed to
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`tls.connect()`. `opts.strictSSL` corresponds to `rejectUnauthorized`.
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#### <a name="opts-local-address"></a> `> opts.localAddress`
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Passed directly to `http` and `https` request calls. Determines the local
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address to bind to.
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#### <a name="opts-max-sockets"></a> `> opts.maxSockets`
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Default: 15
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Maximum number of active concurrent sockets to use for the underlying
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Http/Https/Proxy agents. This setting applies once per spawned agent.
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15 is probably a _pretty good value_ for most use-cases, and balances speed
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with, uh, not knocking out people's routers. 🤓
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#### <a name="opts-retry"></a> `> opts.retry`
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An object that can be used to tune request retry settings. Retries will only be attempted on the following conditions:
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* Request method is NOT `POST` AND
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* Request status is one of: `408`, `420`, `429`, or any status in the 500-range. OR
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* Request errored with `ECONNRESET`, `ECONNREFUSED`, `EADDRINUSE`, `ETIMEDOUT`, or the `fetch` error `request-timeout`.
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The following are worth noting as explicitly not retried:
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* `getaddrinfo ENOTFOUND` and will be assumed to be either an unreachable domain or the user will be assumed offline. If a response is cached, it will be returned immediately.
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If `opts.retry` is `false`, it is equivalent to `{retries: 0}`
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If `opts.retry` is a number, it is equivalent to `{retries: num}`
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The following retry options are available if you want more control over it:
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* retries
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* factor
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* minTimeout
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* maxTimeout
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* randomize
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For details on what each of these do, refer to the [`retry`](https://npm.im/retry) documentation.
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##### Example
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```javascript
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fetch('https://flaky.site.com', {
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retry: {
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retries: 10,
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randomize: true
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}
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})
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fetch('http://reliable.site.com', {
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retry: false
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})
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fetch('http://one-more.site.com', {
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retry: 3
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})
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```
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#### <a name="opts-onretry"></a> `> opts.onRetry`
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A function called whenever a retry is attempted.
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##### Example
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```javascript
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fetch('https://flaky.site.com', {
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onRetry() {
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console.log('we will retry!')
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}
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})
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```
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#### <a name="opts-integrity"></a> `> opts.integrity`
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Matches the response body against the given [Subresource Integrity](https://developer.mozilla.org/en-US/docs/Web/Security/Subresource_Integrity) metadata. If verification fails, the request will fail with an `EINTEGRITY` error.
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`integrity` may either be a string or an [`ssri`](https://npm.im/ssri) `Integrity`-like.
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##### Example
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```javascript
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fetch('https://registry.npmjs.org/make-fetch-happen/-/make-fetch-happen-1.0.0.tgz', {
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integrity: 'sha1-o47j7zAYnedYFn1dF/fR9OV3z8Q='
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}) // -> ok
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fetch('https://malicious-registry.org/make-fetch-happen/-/make-fetch-happen-1.0.0.tgz', {
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integrity: 'sha1-o47j7zAYnedYFn1dF/fR9OV3z8Q='
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}) // Error: EINTEGRITY
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```
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#### <a name="opts-dns"></a> `> opts.dns`
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An object that provides options for the built-in DNS cache. The following options are available:
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Note: Due to limitations in the current proxy agent implementation, users of proxies will not benefit from the DNS cache.
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* `ttl`: Milliseconds to keep cached DNS responses for. Defaults to `5 * 60 * 1000` (5 minutes)
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* `lookup`: A custom lookup function, see [`dns.lookup()`](https://nodejs.org/api/dns.html#dnslookuphostname-options-callback) for implementation details. Defaults to `require('dns').lookup`.
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