Request preferences
Read a preference such as a theme or locale from an incoming request cookie.
Express.js · Pipe
req.cookies
req.cookies is an object populated by cookie-parser with cookies sent by the request. It is empty when no cookies are present; signed cookies belong in req.signedCookies.
How it works
After cookie-parser runs, Express exposes incoming cookie name-value pairs through req.cookies. Read a cookie by property name; when the request has no cookies, the object is empty. Cookies signed with a secret are exposed separately through req.signedCookies.
Syntax
req.cookiesReturns
An object containing cookies sent by the request, or {} when none are present.
Key points
- req.cookies is populated by cookie-parser with cookies received in the HTTP request.
- The property is an empty object when the request contains no cookies.
- Use req.signedCookies for signed cookies rather than reading them from req.cookies.
Common mistakes
- Signed cookies are not read from req.cookies; use req.signedCookies instead.
- Handle the empty object when a client sends no cookies.
Example: Read a request cookie
const express = require('express');
const cookieParser = require('cookie-parser');
const app = express();
app.use(cookieParser());
app.get('/theme', (req, res) => {
res.json({ theme: req.cookies.theme ?? 'default' });
});
app.listen(3000);This app parses incoming cookies and returns the requested theme, falling back when the cookie is absent.
When to use it
Request validation
Inspect an authentication-related cookie before applying application-specific validation.
Middleware processing
Pass parsed cookie values to middleware that validates or uses them.
Related
req.signedCookiescookie-parserreq