Request Cookie Store

An implementation of the Cookie Store API for request handlers.

It uses the Cookie header of a request to populate the store and keeps a record of changes that can be exported as a list of Set-Cookie headers.

It is intended as a cookie middleware for Cloudflare Workers, but perhaps there are other uses as well.

Recipes

The following snippets should convey how this is intended to be used. Aso see the interface for more usage options.

Creating a New Store

import { RequestCookieStore } from '@werker/request-cookie-store';

const example = new Request('/', { headers: { 'cookie': 'foo=bar; fizz=buzz' } });

const cookieStore = new RequestCookieStore(example);

We can now access cookie values from the store like so:

const value = (await cookieStore.get(name))?.value;

Fast Read Access

To avoid using await for every read, we can parse all cookies into a Map once:

type Cookies = ReadonlyMap<string, string>;

const all = await cookieStore.getAll();
const cookies: Cookies = new Map(all.map(({ name, value }) => [name, value]));

// => Map { "foo" => "bar", "fizz" => "buzz" }

Exporting Headers

Use set on the cookie store to add cookies and include them in a response.

await cookieStore.set('foo', 'buzz');
await cookieStore.set('fizz', 'bar');

event.respondWith(new Response(null, cookieStore));

Will produce the following HTTP:

HTTP/1.1 200 OK
content-length: 0
set-cookie: foo=buzz
set-cookie: fizz=bar

Note that due to the weirdness of the Fetch API Headers class, inspecting the response in JS will not produce the intended result! However, Cloudflare Workers do put the correct Set-Cookie headers on the network!

Combine With Other Headers

The above example uses a shortcut. To add additional headers to a response, you can do the following:

const response = new Response(null, {
  headers: [
    ...new Headers({ 'X-Accept': 'app/json' }),
    ...cookieStore.headers,
  ],
});
// or set imperatively:
response.headers.set('X-Content-Type', 'app/json');

Disclaimers

This is not a polyfill! It is intended as a cookie middleware for Cloudflare Workers!

Due to the weirdness of the Fetch API Headers class wrt Set-Cookie (or rather, the lack of special treatment), it is not likely to work in a Service Worker.