4 [![npm version][npm-image]][npm-url]
5 [![build status][travis-image]][travis-url]
6 [![coverage status][codecov-image]][codecov-url]
7 [![install size][install-size-image]][install-size-url]
8 [![Discord][discord-image]][discord-url]
10 A light-weight module that brings `window.fetch` to Node.js
12 (We are looking for [v2 maintainers and collaborators](https://github.com/bitinn/node-fetch/issues/567))
14 [![Backers][opencollective-image]][opencollective-url]
18 - [Motivation](#motivation)
19 - [Features](#features)
20 - [Difference from client-side fetch](#difference-from-client-side-fetch)
21 - [Installation](#installation)
22 - [Loading and configuring the module](#loading-and-configuring-the-module)
23 - [Common Usage](#common-usage)
24 - [Plain text or HTML](#plain-text-or-html)
26 - [Simple Post](#simple-post)
27 - [Post with JSON](#post-with-json)
28 - [Post with form parameters](#post-with-form-parameters)
29 - [Handling exceptions](#handling-exceptions)
30 - [Handling client and server errors](#handling-client-and-server-errors)
31 - [Advanced Usage](#advanced-usage)
34 - [Accessing Headers and other Meta data](#accessing-headers-and-other-meta-data)
35 - [Extract Set-Cookie Header](#extract-set-cookie-header)
36 - [Post data using a file stream](#post-data-using-a-file-stream)
37 - [Post with form-data (detect multipart)](#post-with-form-data-detect-multipart)
38 - [Request cancellation with AbortSignal](#request-cancellation-with-abortsignal)
40 - [fetch(url[, options])](#fetchurl-options)
42 - [Class: Request](#class-request)
43 - [Class: Response](#class-response)
44 - [Class: Headers](#class-headers)
45 - [Interface: Body](#interface-body)
46 - [Class: FetchError](#class-fetcherror)
48 - [Acknowledgement](#acknowledgement)
54 Instead of implementing `XMLHttpRequest` in Node.js to run browser-specific [Fetch polyfill](https://github.com/github/fetch), why not go from native `http` to `fetch` API directly? Hence, `node-fetch`, minimal code for a `window.fetch` compatible API on Node.js runtime.
56 See Matt Andrews' [isomorphic-fetch](https://github.com/matthew-andrews/isomorphic-fetch) or Leonardo Quixada's [cross-fetch](https://github.com/lquixada/cross-fetch) for isomorphic usage (exports `node-fetch` for server-side, `whatwg-fetch` for client-side).
60 - Stay consistent with `window.fetch` API.
61 - Make conscious trade-off when following [WHATWG fetch spec][whatwg-fetch] and [stream spec](https://streams.spec.whatwg.org/) implementation details, document known differences.
62 - Use native promise but allow substituting it with [insert your favorite promise library].
63 - Use native Node streams for body on both request and response.
64 - Decode content encoding (gzip/deflate) properly and convert string output (such as `res.text()` and `res.json()`) to UTF-8 automatically.
65 - Useful extensions such as timeout, redirect limit, response size limit, [explicit errors](ERROR-HANDLING.md) for troubleshooting.
67 ## Difference from client-side fetch
69 - See [Known Differences](LIMITS.md) for details.
70 - If you happen to use a missing feature that `window.fetch` offers, feel free to open an issue.
71 - Pull requests are welcomed too!
75 Current stable release (`2.x`)
78 $ npm install node-fetch
81 ## Loading and configuring the module
82 We suggest you load the module via `require` until the stabilization of ES modules in node:
84 const fetch = require('node-fetch');
87 If you are using a Promise library other than native, set it through `fetch.Promise`:
89 const Bluebird = require('bluebird');
91 fetch.Promise = Bluebird;
96 NOTE: The documentation below is up-to-date with `2.x` releases; see the [`1.x` readme](https://github.com/bitinn/node-fetch/blob/1.x/README.md), [changelog](https://github.com/bitinn/node-fetch/blob/1.x/CHANGELOG.md) and [2.x upgrade guide](UPGRADE-GUIDE.md) for the differences.
98 #### Plain text or HTML
100 fetch('https://github.com/')
101 .then(res => res.text())
102 .then(body => console.log(body));
109 fetch('https://api.github.com/users/github')
110 .then(res => res.json())
111 .then(json => console.log(json));
116 fetch('https://httpbin.org/post', { method: 'POST', body: 'a=1' })
117 .then(res => res.json()) // expecting a json response
118 .then(json => console.log(json));
124 const body = { a: 1 };
126 fetch('https://httpbin.org/post', {
128 body: JSON.stringify(body),
129 headers: { 'Content-Type': 'application/json' },
131 .then(res => res.json())
132 .then(json => console.log(json));
135 #### Post with form parameters
136 `URLSearchParams` is available in Node.js as of v7.5.0. See [official documentation](https://nodejs.org/api/url.html#url_class_urlsearchparams) for more usage methods.
138 NOTE: The `Content-Type` header is only set automatically to `x-www-form-urlencoded` when an instance of `URLSearchParams` is given as such:
141 const { URLSearchParams } = require('url');
143 const params = new URLSearchParams();
144 params.append('a', 1);
146 fetch('https://httpbin.org/post', { method: 'POST', body: params })
147 .then(res => res.json())
148 .then(json => console.log(json));
151 #### Handling exceptions
152 NOTE: 3xx-5xx responses are *NOT* exceptions and should be handled in `then()`; see the next section for more information.
154 Adding a catch to the fetch promise chain will catch *all* exceptions, such as errors originating from node core libraries, network errors and operational errors, which are instances of FetchError. See the [error handling document](ERROR-HANDLING.md) for more details.
157 fetch('https://domain.invalid/')
158 .catch(err => console.error(err));
161 #### Handling client and server errors
162 It is common to create a helper function to check that the response contains no client (4xx) or server (5xx) error responses:
165 function checkStatus(res) {
166 if (res.ok) { // res.status >= 200 && res.status < 300
169 throw MyCustomError(res.statusText);
173 fetch('https://httpbin.org/status/400')
175 .then(res => console.log('will not get here...'))
181 The "Node.js way" is to use streams when possible:
184 fetch('https://assets-cdn.github.com/images/modules/logos_page/Octocat.png')
186 const dest = fs.createWriteStream('./octocat.png');
192 If you prefer to cache binary data in full, use buffer(). (NOTE: `buffer()` is a `node-fetch`-only API)
195 const fileType = require('file-type');
197 fetch('https://assets-cdn.github.com/images/modules/logos_page/Octocat.png')
198 .then(res => res.buffer())
199 .then(buffer => fileType(buffer))
200 .then(type => { /* ... */ });
203 #### Accessing Headers and other Meta data
205 fetch('https://github.com/')
208 console.log(res.status);
209 console.log(res.statusText);
210 console.log(res.headers.raw());
211 console.log(res.headers.get('content-type'));
215 #### Extract Set-Cookie Header
217 Unlike browsers, you can access raw `Set-Cookie` headers manually using `Headers.raw()`. This is a `node-fetch` only API.
220 fetch(url).then(res => {
221 // returns an array of values, instead of a string of comma-separated values
222 console.log(res.headers.raw()['set-cookie']);
226 #### Post data using a file stream
229 const { createReadStream } = require('fs');
231 const stream = createReadStream('input.txt');
233 fetch('https://httpbin.org/post', { method: 'POST', body: stream })
234 .then(res => res.json())
235 .then(json => console.log(json));
238 #### Post with form-data (detect multipart)
241 const FormData = require('form-data');
243 const form = new FormData();
246 fetch('https://httpbin.org/post', { method: 'POST', body: form })
247 .then(res => res.json())
248 .then(json => console.log(json));
250 // OR, using custom headers
251 // NOTE: getHeaders() is non-standard API
253 const form = new FormData();
259 headers: form.getHeaders()
262 fetch('https://httpbin.org/post', options)
263 .then(res => res.json())
264 .then(json => console.log(json));
267 #### Request cancellation with AbortSignal
269 > NOTE: You may cancel streamed requests only on Node >= v8.0.0
271 You may cancel requests with `AbortController`. A suggested implementation is [`abort-controller`](https://www.npmjs.com/package/abort-controller).
273 An example of timing out a request after 150ms could be achieved as the following:
276 import AbortController from 'abort-controller';
278 const controller = new AbortController();
279 const timeout = setTimeout(
280 () => { controller.abort(); },
284 fetch(url, { signal: controller.signal })
285 .then(res => res.json())
291 if (err.name === 'AbortError') {
292 // request was aborted
297 clearTimeout(timeout);
301 See [test cases](https://github.com/bitinn/node-fetch/blob/master/test/test.js) for more examples.
306 ### fetch(url[, options])
308 - `url` A string representing the URL for fetching
309 - `options` [Options](#fetch-options) for the HTTP(S) request
310 - Returns: <code>Promise<[Response](#class-response)></code>
312 Perform an HTTP(S) fetch.
314 `url` should be an absolute url, such as `https://example.com/`. A path-relative URL (`/file/under/root`) or protocol-relative URL (`//can-be-http-or-https.com/`) will result in a rejected `Promise`.
316 <a id="fetch-options"></a>
319 The default values are shown after each option key.
323 // These properties are part of the Fetch Standard
325 headers: {}, // request headers. format is the identical to that accepted by the Headers constructor (see below)
326 body: null, // request body. can be null, a string, a Buffer, a Blob, or a Node.js Readable stream
327 redirect: 'follow', // set to `manual` to extract redirect headers, `error` to reject redirect
328 signal: null, // pass an instance of AbortSignal to optionally abort requests
330 // The following properties are node-fetch extensions
331 follow: 20, // maximum redirect count. 0 to not follow redirect
332 timeout: 0, // req/res timeout in ms, it resets on redirect. 0 to disable (OS limit applies). Signal is recommended instead.
333 compress: true, // support gzip/deflate content encoding. false to disable
334 size: 0, // maximum response body size in bytes. 0 to disable
335 agent: null // http(s).Agent instance or function that returns an instance (see below)
339 ##### Default Headers
341 If no values are set, the following request headers will be sent automatically:
344 ------------------- | --------------------------------------------------------
345 `Accept-Encoding` | `gzip,deflate` _(when `options.compress === true`)_
347 `Connection` | `close` _(when no `options.agent` is present)_
348 `Content-Length` | _(automatically calculated, if possible)_
349 `Transfer-Encoding` | `chunked` _(when `req.body` is a stream)_
350 `User-Agent` | `node-fetch/1.0 (+https://github.com/bitinn/node-fetch)`
352 Note: when `body` is a `Stream`, `Content-Length` is not set automatically.
356 The `agent` option allows you to specify networking related options which are out of the scope of Fetch, including and not limited to the following:
358 - Support self-signed certificate
359 - Use only IPv4 or IPv6
362 See [`http.Agent`](https://nodejs.org/api/http.html#http_new_agent_options) for more information.
364 In addition, the `agent` option accepts a function that returns `http`(s)`.Agent` instance given current [URL](https://nodejs.org/api/url.html), this is useful during a redirection chain across HTTP and HTTPS protocol.
367 const httpAgent = new http.Agent({
370 const httpsAgent = new https.Agent({
375 agent: function (_parsedURL) {
376 if (_parsedURL.protocol == 'http:') {
385 <a id="class-request"></a>
388 An HTTP(S) request containing information about URL, method, headers, and the body. This class implements the [Body](#iface-body) interface.
390 Due to the nature of Node.js, the following properties are not implemented at this moment:
402 The following node-fetch extension properties are provided:
409 See [options](#fetch-options) for exact meaning of these extensions.
411 #### new Request(input[, options])
413 <small>*(spec-compliant)*</small>
415 - `input` A string representing a URL, or another `Request` (which will be cloned)
416 - `options` [Options][#fetch-options] for the HTTP(S) request
418 Constructs a new `Request` object. The constructor is identical to that in the [browser](https://developer.mozilla.org/en-US/docs/Web/API/Request/Request).
420 In most cases, directly `fetch(url, options)` is simpler than creating a `Request` object.
422 <a id="class-response"></a>
425 An HTTP(S) response. This class implements the [Body](#iface-body) interface.
427 The following properties are not implemented in node-fetch at this moment:
430 - `Response.redirect()`
434 #### new Response([body[, options]])
436 <small>*(spec-compliant)*</small>
438 - `body` A `String` or [`Readable` stream][node-readable]
439 - `options` A [`ResponseInit`][response-init] options dictionary
441 Constructs a new `Response` object. The constructor is identical to that in the [browser](https://developer.mozilla.org/en-US/docs/Web/API/Response/Response).
443 Because Node.js does not implement service workers (for which this class was designed), one rarely has to construct a `Response` directly.
447 <small>*(spec-compliant)*</small>
449 Convenience property representing if the request ended normally. Will evaluate to true if the response status was greater than or equal to 200 but smaller than 300.
451 #### response.redirected
453 <small>*(spec-compliant)*</small>
455 Convenience property representing if the request has been redirected at least once. Will evaluate to true if the internal redirect counter is greater than 0.
457 <a id="class-headers"></a>
460 This class allows manipulating and iterating over a set of HTTP headers. All methods specified in the [Fetch Standard][whatwg-fetch] are implemented.
462 #### new Headers([init])
464 <small>*(spec-compliant)*</small>
466 - `init` Optional argument to pre-fill the `Headers` object
468 Construct a new `Headers` object. `init` can be either `null`, a `Headers` object, an key-value map object or any iterable object.
471 // Example adapted from https://fetch.spec.whatwg.org/#example-headers-class
474 'Content-Type': 'text/xml',
477 const headers = new Headers(meta);
479 // The above is equivalent to
481 [ 'Content-Type', 'text/xml' ],
482 [ 'Breaking-Bad', '<3' ]
484 const headers = new Headers(meta);
486 // You can in fact use any iterable objects, like a Map or even another Headers
487 const meta = new Map();
488 meta.set('Content-Type', 'text/xml');
489 meta.set('Breaking-Bad', '<3');
490 const headers = new Headers(meta);
491 const copyOfHeaders = new Headers(headers);
494 <a id="iface-body"></a>
497 `Body` is an abstract interface with methods that are applicable to both `Request` and `Response` classes.
499 The following methods are not yet implemented in node-fetch at this moment:
505 <small>*(deviation from spec)*</small>
507 * Node.js [`Readable` stream][node-readable]
509 Data are encapsulated in the `Body` object. Note that while the [Fetch Standard][whatwg-fetch] requires the property to always be a WHATWG `ReadableStream`, in node-fetch it is a Node.js [`Readable` stream][node-readable].
513 <small>*(spec-compliant)*</small>
517 A boolean property for if this body has been consumed. Per the specs, a consumed body cannot be used again.
519 #### body.arrayBuffer()
524 <small>*(spec-compliant)*</small>
526 * Returns: <code>Promise</code>
528 Consume the body and return a promise that will resolve to one of these formats.
532 <small>*(node-fetch extension)*</small>
534 * Returns: <code>Promise<Buffer></code>
536 Consume the body and return a promise that will resolve to a Buffer.
538 #### body.textConverted()
540 <small>*(node-fetch extension)*</small>
542 * Returns: <code>Promise<String></code>
544 Identical to `body.text()`, except instead of always converting to UTF-8, encoding sniffing will be performed and text converted to UTF-8 if possible.
546 (This API requires an optional dependency of the npm package [encoding](https://www.npmjs.com/package/encoding), which you need to install manually. `webpack` users may see [a warning message](https://github.com/bitinn/node-fetch/issues/412#issuecomment-379007792) due to this optional dependency.)
548 <a id="class-fetcherror"></a>
549 ### Class: FetchError
551 <small>*(node-fetch extension)*</small>
553 An operational error in the fetching process. See [ERROR-HANDLING.md][] for more info.
555 <a id="class-aborterror"></a>
556 ### Class: AbortError
558 <small>*(node-fetch extension)*</small>
560 An Error thrown when the request is aborted in response to an `AbortSignal`'s `abort` event. It has a `name` property of `AbortError`. See [ERROR-HANDLING.MD][] for more info.
564 Thanks to [github/fetch](https://github.com/github/fetch) for providing a solid implementation reference.
566 `node-fetch` v1 was maintained by [@bitinn](https://github.com/bitinn); v2 was maintained by [@TimothyGu](https://github.com/timothygu), [@bitinn](https://github.com/bitinn) and [@jimmywarting](https://github.com/jimmywarting); v2 readme is written by [@jkantr](https://github.com/jkantr).
572 [npm-image]: https://flat.badgen.net/npm/v/node-fetch
573 [npm-url]: https://www.npmjs.com/package/node-fetch
574 [travis-image]: https://flat.badgen.net/travis/bitinn/node-fetch
575 [travis-url]: https://travis-ci.org/bitinn/node-fetch
576 [codecov-image]: https://flat.badgen.net/codecov/c/github/bitinn/node-fetch/master
577 [codecov-url]: https://codecov.io/gh/bitinn/node-fetch
578 [install-size-image]: https://flat.badgen.net/packagephobia/install/node-fetch
579 [install-size-url]: https://packagephobia.now.sh/result?p=node-fetch
580 [discord-image]: https://img.shields.io/discord/619915844268326952?color=%237289DA&label=Discord&style=flat-square
581 [discord-url]: https://discord.gg/Zxbndcm
582 [opencollective-image]: https://opencollective.com/node-fetch/backers.svg
583 [opencollective-url]: https://opencollective.com/node-fetch
584 [whatwg-fetch]: https://fetch.spec.whatwg.org/
585 [response-init]: https://fetch.spec.whatwg.org/#responseinit
586 [node-readable]: https://nodejs.org/api/stream.html#stream_readable_streams
587 [mdn-headers]: https://developer.mozilla.org/en-US/docs/Web/API/Headers
588 [LIMITS.md]: https://github.com/bitinn/node-fetch/blob/master/LIMITS.md
589 [ERROR-HANDLING.md]: https://github.com/bitinn/node-fetch/blob/master/ERROR-HANDLING.md
590 [UPGRADE-GUIDE.md]: https://github.com/bitinn/node-fetch/blob/master/UPGRADE-GUIDE.md