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undici exports a set of cookie utility functions for working with HTTP Cookie and Set-Cookie headers. These functions operate directly on undici’s Headers objects and follow the WHATWG cookie specification.

​
Importing

import { getCookies, getSetCookies, setCookie, deleteCookie, parseCookie } from 'undici'
All cookie functions work with the Cookie object:
​
name
string
The cookie name.
​
value
string
The cookie value.
​
expires
Date | number
Expiry date or Unix timestamp in milliseconds.
​
maxAge
number
Max-Age in seconds.
​
domain
string
The domain attribute.
​
path
string
The path attribute.
​
secure
boolean
Whether the Secure flag is set.
​
httpOnly
boolean
Whether the HttpOnly flag is set.
​
sameSite
'Strict' | 'Lax' | 'None'
The SameSite attribute value.
​
unparsed
string[]
Left-over attributes that were not parsed.

​
getCookies(headers)

Parses the Cookie request header and returns a key-value map of all cookie name/value pairs.
​
headers
Headers
required
A Headers instance containing the Cookie header.
Returns: Record<string, string>
Parsing request cookies
import { getCookies, Headers } from 'undici'

const headers = new Headers({
  cookie: 'session=abc123; user=alice; theme=dark'
})

const cookies = getCookies(headers)
console.log(cookies)
// { session: 'abc123', user: 'alice', theme: 'dark' }

console.log(cookies.session) // 'abc123'

​
getSetCookies(headers)

Parses all Set-Cookie response headers and returns an array of Cookie objects.
​
headers
Headers
required
A Headers instance containing one or more Set-Cookie headers.
Returns: Cookie[]
Parsing Set-Cookie response headers
import { getSetCookies, Headers } from 'undici'

const headers = new Headers({
  'set-cookie': 'undici=getSetCookies; Secure; HttpOnly; SameSite=Strict'
})

const cookies = getSetCookies(headers)
console.log(cookies)
// [
//   {
//     name: 'undici',
//     value: 'getSetCookies',
//     secure: true,
//     httpOnly: true,
//     sameSite: 'Strict'
//   }
// ]
Appends a Set-Cookie header to a Headers instance.
​
headers
Headers
required
A Headers instance to append the cookie to.
​
cookie
Cookie
required
The cookie to set.
Returns: void
Setting cookies on a response
import { setCookie, Headers } from 'undici'

const headers = new Headers()

setCookie(headers, {
  name: 'session',
  value: 'abc123',
  httpOnly: true,
  secure: true,
  sameSite: 'Lax',
  path: '/',
  maxAge: 3600
})

console.log(headers.get('set-cookie'))
// 'session=abc123; Path=/; Max-Age=3600; Secure; HttpOnly; SameSite=Lax'

​
deleteCookie(headers, name[, attributes])

Sets a cookie’s expiry to the Unix epoch (January 1, 1970), signaling browsers to delete it.
​
headers
Headers
required
A Headers instance to append the delete instruction to.
​
name
string
required
The name of the cookie to delete.
​
attributes
object
Optional path and domain to scope the deletion.
Returns: void
Deleting a cookie
import { deleteCookie, Headers } from 'undici'

const headers = new Headers()
deleteCookie(headers, 'session')

console.log(headers.get('set-cookie'))
// 'session=; Expires=Thu, 01 Jan 1970 00:00:00 GMT'

// With path and domain
deleteCookie(headers, 'user', { path: '/app', domain: 'example.com' })

​
parseCookie(cookieString)

Parses a raw cookie string into a Cookie object.
​
cookieString
string
required
A raw Set-Cookie header value string.
Returns: Cookie 
import { parseCookie } from 'undici'

const cookie = parseCookie('session=abc123; Path=/; HttpOnly; Secure; SameSite=Lax')
console.log(cookie.name)    // 'session'
console.log(cookie.value)   // 'abc123'
console.log(cookie.httpOnly) // true

​
Working with fetch responses

Use getSetCookies with fetch responses to inspect cookies returned by the server:
Inspecting cookies from a fetch response
import { fetch, getSetCookies } from 'undici'

const response = await fetch('https://api.example.com/login', {
  method: 'POST',
  body: JSON.stringify({ username: 'alice', password: 'secret' }),
  headers: { 'content-type': 'application/json' }
})

const cookies = getSetCookies(response.headers)
const sessionCookie = cookies.find(c => c.name === 'session')
console.log(sessionCookie?.value)

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