set-cookie-parser

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ℹ️ Note for current users: I'm considering some changes for the next major version and would appreciate your feedback: #68

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Parses set-cookie headers into JavaScript objects

Accepts a single set-cookie header value, an array of set-cookie header values, a Node.js response object, or a fetch() Response object that may have 0 or more set-cookie headers.

Also accepts an optional options object. Defaults:

{
    decodeValues: true,  // Calls decodeURIComponent on each value - default: true
    map: false,          // Return an object instead of an array - default: false
    silent: false,       // Suppress the warning that is logged when called on a request instead of a response - default: false
}

Returns either an array of cookie objects or a map of name => cookie object with {map: true}. Each cookie object will have, at a minimum name and value properties, and may have additional properties depending on the set-cookie header:

• name - cookie name (string)
• value - cookie value (string)
• path - URL path to limit the scope to (string or undefined)
• domain - domain to expand the scope to (string or undefined, may begin with "." to indicate the named domain or any subdomain of it)
• expires - absolute expiration date for the cookie (Date object or undefined)
• maxAge - relative expiration time of the cookie in seconds from when the client receives it (integer or undefined)
  • Note: when using with express's res.cookie() method, multiply maxAge by 1000 to convert to milliseconds.
• secure - indicates cookie should only be sent over HTTPs (true or undefined)
• httpOnly - indicates cookie should not be accessible to client-side JavaScript (true or undefined)
• sameSite - indicates if cookie should be included in cross-site requests (more info) (string or undefined)
  • Note: valid values are "Strict", "Lax", and "None", but set-cookie-parser coppies the value verbatim and does not perform any validation.
• partitioned - indicates cookie should be scoped to the combination of 3rd party domain + top page domain (more info) (true or undefined)

(The output format is loosely based on the input format of https://www.npmjs.com/package/cookie)

Install

$ npm install --save set-cookie-parser

Usage

Get array of cookie objects

var http = require('http');
var setCookie = require('set-cookie-parser');

http.get('http://example.com', function(res) {
  var cookies = setCookie.parse(res, {
    decodeValues: true  // default: true
  });

  cookies.forEach(console.log);
}

Example output:

[
    {
        name: 'bam',
        value: 'baz'
    },
    {
        name: 'foo',
        value: 'bar',
        path: '/',
        expires: new Date('Tue Jul 01 2025 06:01:11 GMT-0400 (EDT)'),
        maxAge: 1000,
        domain: '.example.com',
        secure: true,
        httpOnly: true,
        sameSite: 'lax'
    }
]

Get map of cookie objects

var http = require('http');
var setCookie = require('set-cookie-parser');

http.get('http://example.com', function(res) {
  var cookies = setCookie.parse(res, {
    decodeValues: true,  // default: true
    map: true            // default: false
  });

  var desiredCookie = cookies['session'];
  console.log(desiredCookie);
});

Example output:

{
    bam: {
        name: 'bam',
        value: 'baz'
    },
    foo: {
        name: 'foo',
        value: 'bar',
        path: '/',
        expires: new Date('Tue Jul 01 2025 06:01:11 GMT-0400 (EDT)'),
        maxAge: 1000,
        domain: '.example.com',
        secure: true,
        httpOnly: true,
        sameSite: 'lax'
    }
}

Creating a new, modified set-cookie header

This library can be used in conjunction with the cookie library to modify and replace set-cookie headers:

const libCookie = require('cookie');
const setCookie = require('set-cookie-parser');

function modifySetCookie(res){
  // parse the set-cookie headers with this library
  let cookies = setCookie.parse(res);
  
  // modify the cookies here
  // ...
  
  // create new set-cookie headers using the cookie library
  res.headers['set-cookie'] = cookies.map(function(cookie) {
      return libCookie.serialize(cookie.name, cookie.value, cookie);
  });
}

See a real-world example of this in unblocker

Usage in React Native (and with some other fetch implementations)

React Native follows the Fetch spec more closely and combines all of the Set-Cookie header values into a single string. The splitCookiesString method reverses this.

var setCookie = require('set-cookie-parser');

var response = fetch(/*...*/);

// This is mainly for React Native; Node.js does not combine set-cookie headers.
var combinedCookieHeader = response.headers.get('Set-Cookie');
var splitCookieHeaders = setCookie.splitCookiesString(combinedCookieHeader)
var cookies = setCookie.parse(splitCookieHeaders);

console.log(cookies); // should be an array of cookies

This behavior may become a default part of parse in the next major release, but requires the extra step for now.

Note that the fetch() spec now includes a getSetCookie() method that provides un-combined Set-Cookie headers. This library will automatically use that method if it is present.

API

parse(input, [options])

Parses cookies from a string, array of strings, or a http response object. Always returns an array, regardless of input format. (Unless the map option is set, in which case it always returns an object.)

parseString(individualSetCookieHeader, [options])

Parses a single set-cookie header value string. Options default is {decodeValues: true}. Used under-the-hood by parse(). Returns an object.

splitCookiesString(combinedSetCookieHeader)

It's uncommon, but the HTTP spec does allow for multiple of the same header to have their values combined (comma-separated) into a single header. This method splits apart a combined header without choking on commas that appear within a cookie's value (or expiration date). Returns an array of strings that may be passed to parse().

References

• RFC 6265: HTTP State Management Mechanism
• draft-ietf-httpbis-rfc6265bis-10

License

MIT © Nathan Friedly