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npm/node-fetch-npm

Name: node-fetch-npm

Owner: npm

Description: A light-weight module that brings window.fetch to Node.js

Forked from: iarna/node-fetch

Created: 2017-04-26 22:32:07.0

Updated: 2018-01-25 03:07:36.0

Pushed: 2017-08-24 17:48:05.0

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Size: 472

Language: JavaScript

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README

node-fetch-npm

A light-weight module that brings window.fetch to Node.js

node-fetch-npm is a fork of node-fetch used in npm itself, through make-fetch-happen. It has more regular releases and accepts some patches that would not fit with node-fetch's own design goals (such as picking a specific cookie library, removing babel dependency altogether, etc).

This library is not a replacement for node-fetch, nor does it intend to supplant it. It's purely a fork maintained for the sake of easier patching of specific needs that it wouldn't be fair to shove down the main project's throat. This project will still send patches for shared bugs over and hopefully help improve its “parent”.

Motivation

Instead of implementing XMLHttpRequest in Node.js to run browser-specific Fetch polyfill, 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.

See Matt Andrews' isomorphic-fetch for isomorphic usage (exports node-fetch for server-side, whatwg-fetch for client-side).

Features

Stay consistent with window.fetch API.
Make conscious trade-off when following whatwg fetch spec and stream spec implementation details, document known difference.
Use native promise, but allow substituting it with [insert your favorite promise library].
Use native stream for body, on both request and response.
Decode content encoding (gzip/deflate) properly, and convert string output (such as res.text() and res.json()) to UTF-8 automatically.
Useful extensions such as timeout, redirect limit, response size limit, [explicit errors][] for troubleshooting.

Difference from client-side fetch

See Known Differences for details.
If you happen to use a missing feature that window.fetch offers, feel free to open an issue.
Pull requests are welcomed too!

Install

m install node-fetch-npm --save

Usage

rt fetch from 'node-fetch';
r
onst fetch = require('node-fetch');

f you are using your own Promise library, set it through fetch.Promise. Eg.

mport Bluebird from 'bluebird';
etch.Promise = Bluebird;

lain text or html

h('https://github.com/')
.then(res => res.text())
.then(body => console.log(body));

son

h('https://api.github.com/users/github')
.then(res => res.json())
.then(json => console.log(json));

atching network error
xx-5xx responses are NOT network errors, and should be handled in then()
ou only need one catch() at the end of your promise chain

h('http://domain.invalid/')
.catch(err => console.error(err));

tream
he node.js way is to use stream when possible

h('https://assets-cdn.github.com/images/modules/logos_page/Octocat.png')
.then(res => {
    const dest = fs.createWriteStream('./octocat.png');
    res.body.pipe(dest);
});

uffer
f you prefer to cache binary data in full, use buffer()
ote that buffer() is a node-fetch only API

rt fileType from 'file-type';

h('https://assets-cdn.github.com/images/modules/logos_page/Octocat.png')
.then(res => res.buffer())
.then(buffer => fileType(buffer))
.then(type => { /* ... */ });

eta

h('https://github.com/')
.then(res => {
    console.log(res.ok);
    console.log(res.status);
    console.log(res.statusText);
    console.log(res.headers.raw());
    console.log(res.headers.get('content-type'));
});

ost

h('http://httpbin.org/post', { method: 'POST', body: 'a=1' })
.then(res => res.json())
.then(json => console.log(json));

ost with stream from file

rt { createReadStream } from 'fs';

t stream = createReadStream('input.txt');
h('http://httpbin.org/post', { method: 'POST', body: stream })
.then(res => res.json())
.then(json => console.log(json));

ost with JSON

body = { a: 1 };
h('http://httpbin.org/post', {
method: 'POST',
body:    JSON.stringify(body),
headers: { 'Content-Type': 'application/json' },

.then(res => res.json())
.then(json => console.log(json));

ost with form-data (detect multipart)

rt FormData from 'form-data';

t form = new FormData();
.append('a', 1);
h('http://httpbin.org/post', { method: 'POST', body: form })
.then(res => res.json())
.then(json => console.log(json));

ost with form-data (custom headers)
ote that getHeaders() is non-standard API

rt FormData from 'form-data';

t form = new FormData();
.append('a', 1);
h('http://httpbin.org/post', { method: 'POST', body: form, headers: form.getHeaders() })
.then(res => res.json())
.then(json => console.log(json));

ode 7+ with async function

nc function () {
const res = await fetch('https://api.github.com/users/github');
const json = await res.json();
console.log(json);
;

See test cases for more examples.

API

fetch(url[, options])

url A string representing the URL for fetching
options Options for the HTTP(S) request
Returns: Promise<Response>

Perform an HTTP(S) fetch.

url should be an absolute url, such as http://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.

Options

The default values are shown after each option key.


// These properties are part of the Fetch Standard
method: 'GET',
headers: {},        // request headers. format is the identical to that accepted by the Headers constructor (see below)
body: null,         // request body. can be null, a string, a Buffer, a Blob, or a Node.js Readable stream
redirect: 'follow', // set to `manual` to extract redirect headers, `error` to reject redirect

// The following properties are node-fetch-npm extensions
follow: 20,         // maximum redirect count. 0 to not follow redirect
timeout: 0,         // req/res timeout in ms, it resets on redirect. 0 to disable (OS limit applies)
compress: true,     // support gzip/deflate content encoding. false to disable
size: 0,            // maximum response body size in bytes. 0 to disable
agent: null         // http(s).Agent instance, allows custom proxy, certificate etc.

Default Headers

If no values are set, the following request headers will be sent automatically:

Header | Value —————– | ——————————————————– Accept-Encoding | gzip,deflate (when options.compress === true) Accept | */* Connection | close (when no options.agent is present) Content-Length | (automatically calculated, if possible) User-Agent | node-fetch-npm/1.0 (+https://github.com/npm/node-fetch-npm)

Class: Request

An HTTP(S) request containing information about URL, method, headers, and the body. This class implements the Body interface.

Due to the nature of Node.js, the following properties are not implemented at this moment:

type
destination
referrer
referrerPolicy
mode
credentials
cache
integrity
keepalive

The following node-fetch-npm extension properties are provided:

follow
compress
counter
agent

See options for exact meaning of these extensions.

new Request(input[, options])

(spec-compliant)

input A string representing a URL, or another Request (which will be cloned)
options [Options][#fetch-options] for the HTTP(S) request

Constructs a new Request object. The constructor is identical to that in the browser.

In most cases, directly fetch(url, options) is simpler than creating a Request object.

Class: Response

An HTTP(S) response. This class implements the Body interface.

The following properties are not implemented in node-fetch-npm at this moment:

Response.error()
Response.redirect()
type
redirected
trailer

new Response([body[, options]])

(spec-compliant)

body A string or Readable stream
options A ResponseInit options dictionary

Constructs a new Response object. The constructor is identical to that in the browser.

Because Node.js does not implement service workers (for which this class was designed), one rarely has to construct a Response directly.

Class: Headers

This class allows manipulating and iterating over a set of HTTP headers. All methods specified in the Fetch Standard are implemented.

new Headers([init])

(spec-compliant)

init Optional argument to pre-fill the Headers object

Construct a new Headers object. init can be either null, a Headers object, an key-value map object, or any iterable object.

xample adapted from https://fetch.spec.whatwg.org/#example-headers-class

t meta = {
ontent-Type': 'text/xml',
reaking-Bad': '<3'

t headers = new Headers(meta);

he above is equivalent to
t meta = [
'Content-Type', 'text/xml' ],
'Breaking-Bad', '<3' ]

t headers = new Headers(meta);

ou can in fact use any iterable objects, like a Map or even another Headers
t meta = new Map();
.set('Content-Type', 'text/xml');
.set('Breaking-Bad', '<3');
t headers = new Headers(meta);
t copyOfHeaders = new Headers(headers);

Interface: Body

Body is an abstract interface with methods that are applicable to both Request and Response classes.

The following methods are not yet implemented in node-fetch-npm at this moment:

formData()

body.body

(deviation from spec)

Node.js Readable stream

The data encapsulated in the Body object. Note that while the Fetch Standard requires the property to always be a WHATWG ReadableStream, in node-fetch-npm it is a Node.js Readable stream.

body.bodyUsed

(spec-compliant)

Boolean

A boolean property for if this body has been consumed. Per spec, a consumed body cannot be used again.

body.arrayBuffer() body.blob() body.json() body.text()

(spec-compliant)

Returns: Promise

Consume the body and return a promise that will resolve to one of these formats.

body.buffer()

(node-fetch-npm extension)

Returns: Promise<Buffer>

Consume the body and return a promise that will resolve to a Buffer.

body.textConverted()

(node-fetch-npm extension)

Returns: Promise<String>

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.

Class: FetchError

(node-fetch-npm extension)

An operational error in the fetching process. See ERROR-HANDLING.md for more info.

License

MIT

Acknowledgement

Thanks to github/fetch for providing a solid implementation reference.

This work is supported by the National Institutes of Health's National Center for Advancing Translational Sciences, Grant Number U24TR002306. This work is solely the responsibility of the creators and does not necessarily represent the official views of the National Institutes of Health.