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    node-fetchpublic

    node-fetch

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

    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 or Leonardo Quixada's cross-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, convert res.text() output to UTF-8 optionally.
    • 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

    Stable release (2.x)

    $ npm install node-fetch --save

    Usage

    Note that documentation below is up-to-date with 2.x releases, see 1.x readme, changelog and 2.x upgrade guide if you want to find out the difference.

    import fetch from 'node-fetch';
    // or
    // const fetch = require('node-fetch');
     
    // if you are using your own Promise library, set it through fetch.Promise. Eg.
     
    // import Bluebird from 'bluebird';
    // fetch.Promise = Bluebird;
     
    // plain text or html
     
    fetch('https://github.com/')
        .then(res => res.text())
        .then(body => console.log(body));
     
    // json
     
    fetch('https://api.github.com/users/github')
        .then(res => res.json())
        .then(json => console.log(json));
     
    // catching network error
    // 3xx-5xx responses are NOT network errors, and should be handled in then()
    // you only need one catch() at the end of your promise chain
     
    fetch('http://domain.invalid/')
        .catch(err => console.error(err));
     
    // stream
    // the node.js way is to use stream when possible
     
    fetch('https://assets-cdn.github.com/images/modules/logos_page/Octocat.png')
        .then(res => {
            const dest = fs.createWriteStream('./octocat.png');
            res.body.pipe(dest);
        });
     
    // buffer
    // if you prefer to cache binary data in full, use buffer()
    // note that buffer() is a node-fetch only API
     
    import fileType from 'file-type';
     
    fetch('https://assets-cdn.github.com/images/modules/logos_page/Octocat.png')
        .then(res => res.buffer())
        .then(buffer => fileType(buffer))
        .then(type => { /* ... */ });
     
    // meta
     
    fetch('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'));
        });
     
    // post
     
    fetch('http://httpbin.org/post', { method: 'POST', body: 'a=1' })
        .then(res => res.json())
        .then(json => console.log(json));
     
    // post with stream from file
     
    import { createReadStream } from 'fs';
     
    const stream = createReadStream('input.txt');
    fetch('http://httpbin.org/post', { method: 'POST', body: stream })
        .then(res => res.json())
        .then(json => console.log(json));
     
    // post with JSON
     
    var body = { a: 1 };
    fetch('http://httpbin.org/post', { 
        method: 'POST',
        body:    JSON.stringify(body),
        headers: { 'Content-Type': 'application/json' },
    })
        .then(res => res.json())
        .then(json => console.log(json));
     
    // post form parameters (x-www-form-urlencoded)
     
    import { URLSearchParams } from 'url';
     
    const params = new URLSearchParams();
    params.append('a', 1);
    fetch('http://httpbin.org/post', { method: 'POST', body: params })
        .then(res => res.json())
        .then(json => console.log(json));
     
    // post with form-data (detect multipart)
     
    import FormData from 'form-data';
     
    const form = new FormData();
    form.append('a', 1);
    fetch('http://httpbin.org/post', { method: 'POST', body: form })
        .then(res => res.json())
        .then(json => console.log(json));
     
    // post with form-data (custom headers)
    // note that getHeaders() is non-standard API
     
    import FormData from 'form-data';
     
    const form = new FormData();
    form.append('a', 1);
    fetch('http://httpbin.org/post', { method: 'POST', body: form, headers: form.getHeaders() })
        .then(res => res.json())
        .then(json => console.log(json));
     
    // node 7+ with async function
     
    (async 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 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/1.0 (+https://github.com/bitinn/node-fetch)

    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 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 at this moment:

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

    new Response([body[, options]])

    (spec-compliant)

    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.

    response.ok

    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.

    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.

    // Example adapted from https://fetch.spec.whatwg.org/#example-headers-class
     
    const meta = {
      'Content-Type': 'text/xml',
      'Breaking-Bad': '<3'
    };
    const headers = new Headers(meta);
     
    // The above is equivalent to
    const meta = [
      [ 'Content-Type', 'text/xml' ],
      [ 'Breaking-Bad', '<3' ]
    ];
    const headers = new Headers(meta);
     
    // You can in fact use any iterable objects, like a Map or even another Headers
    const meta = new Map();
    meta.set('Content-Type', 'text/xml');
    meta.set('Breaking-Bad', '<3');
    const headers = new Headers(meta);
    const 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 at this moment:

    • formData()

    body.body

    (deviation from spec)

    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 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 extension)

    • Returns: Promise<Buffer>

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

    body.textConverted()

    (node-fetch 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 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.

    install

    npm i node-fetch

    Downloadsweekly downloads

    2,901,274

    version

    2.1.2

    license

    MIT

    repository

    githubgithub

    last publish

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