express-session
Advanced tools
The express-session npm package is a middleware for Express applications that enables server-side session management. It allows you to store and access user data as they interact with your web application. The package creates a session ID for each client and uses it to store data across multiple HTTP requests.
Session Initialization
This code initializes the express-session middleware with a secret to sign the session ID cookie, and configuration options such as 'resave', 'saveUninitialized', and 'cookie' settings.
const express = require('express');
const session = require('express-session');
const app = express();
app.use(session({
secret: 'keyboard cat',
resave: false,
saveUninitialized: true,
cookie: { secure: true }
}));Storing Session Data
This code demonstrates how to store data in the session object. The value 'This is saved in session' is stored under the key 'myValue' in the session.
app.use(session({ /* ... */ }));
app.get('/save', function(req, res) {
// Save a value to the session
req.session.myValue = 'This is saved in session';
res.send('Session value stored.');
});Retrieving Session Data
This code shows how to retrieve data from the session. It accesses the value stored under the key 'myValue' and sends it in the HTTP response.
app.get('/retrieve', function(req, res) {
// Retrieve a value from the session
const myValue = req.session.myValue;
res.send(`Session value: ${myValue}`);
});Destroying a Session
This code provides an example of how to destroy a session, effectively logging out the user. It handles any errors that might occur during the destruction process.
app.get('/logout', function(req, res) {
// Destroy the session
req.session.destroy(function(err) {
if(err) {
return res.send('Error destroying session');
}
res.send('Session destroyed');
});
});The cookie-session package is similar to express-session but stores the session data directly in a cookie on the client-side, rather than on the server. This can be simpler and more scalable for some applications, but it is less secure and has limitations on the amount of data you can store.
Connect-redis is a Redis session store for the express-session package. It requires express-session to be installed and configured, but it uses Redis to store session data, which can be more performant and scalable for applications with a high number of sessions.
Connect-mongo is a MongoDB session store for the express-session package. Similar to connect-redis, it leverages MongoDB to store session data, providing a scalable and performant solution for managing sessions in Express applications.
$ npm install express-session
var express = require('express')
var session = require('express-session')
var app = express()
app.use(session({secret: 'keyboard cat'}))
Setup session store with the given options.
Session data is not saved in the cookie itself, just the session ID.
name - cookie name (formerly known as key). (default: 'connect.sid')store - session store instance.secret - session cookie is signed with this secret to prevent tampering.cookie - session cookie settings.
{ path: '/', httpOnly: true, secure: false, maxAge: null })genid - function to call to generate a new session ID. (default: uses uid2 library)rolling - forces a cookie set on every response. This resets the expiration date. (default: false)resave - forces session to be saved even when unmodified. (default: true)proxy - trust the reverse proxy when setting secure cookies (via "x-forwarded-proto" header). When set to true, the "x-forwarded-proto" header will be used. When set to false, all headers are ignored. When left unset, will use the "trust proxy" setting from express. (default: undefined)saveUninitialized - forces a session that is "uninitialized" to be saved to the store. A session is uninitialized when it is new but not modified. This is useful for implementing login sessions, reducing server storage usage, or complying with laws that require permission before setting a cookie. (default: true)unset - controls result of unsetting req.session (through delete, setting to null, etc.). This can be "keep" to keep the session in the store but ignore modifications or "destroy" to destroy the stored session. (default: 'keep')Generate a custom session ID for new sessions. Provide a function that returns a string that will be used as a session ID. The function is given req as the first argument if you want to use some value attached to req when generating the ID.
NOTE be careful you generate unique IDs so your sessions do not conflict.
app.use(session({
genid: function(req) {
return genuuid(); // use UUIDs for session IDs
},
secret: 'keyboard cat'
}))
Please note that secure: true is a recommended option. However, it requires an https-enabled website, i.e., HTTPS is necessary for secure cookies.
If secure is set, and you access your site over HTTP, the cookie will not be set. If you have your node.js behind a proxy and are using secure: true, you need to set "trust proxy" in express:
var app = express()
app.set('trust proxy', 1) // trust first proxy
app.use(session({
secret: 'keyboard cat',
cookie: { secure: true }
}))
For using secure cookies in production, but allowing for testing in development, the following is an example of enabling this setup based on NODE_ENV in express:
var app = express()
var sess = {
secret: 'keyboard cat',
cookie: {}
}
if (app.get('env') === 'production') {
app.set('trust proxy', 1) // trust first proxy
sess.cookie.secure = true // serve secure cookies
}
app.use(session(sess))
By default cookie.maxAge is null, meaning no "expires" parameter is set
so the cookie becomes a browser-session cookie. When the user closes the
browser the cookie (and session) will be removed.
To store or access session data, simply use the request property req.session,
which is (generally) serialized as JSON by the store, so nested objects
are typically fine. For example below is a user-specific view counter:
app.use(session({ secret: 'keyboard cat', cookie: { maxAge: 60000 }}))
app.use(function(req, res, next) {
var sess = req.session
if (sess.views) {
sess.views++
res.setHeader('Content-Type', 'text/html')
res.write('<p>views: ' + sess.views + '</p>')
res.write('<p>expires in: ' + (sess.cookie.maxAge / 1000) + 's</p>')
res.end()
} else {
sess.views = 1
res.end('welcome to the session demo. refresh!')
}
})
To regenerate the session simply invoke the method, once complete
a new SID and Session instance will be initialized at req.session.
req.session.regenerate(function(err) {
// will have a new session here
})
Destroys the session, removing req.session, will be re-generated next request.
req.session.destroy(function(err) {
// cannot access session here
})
Reloads the session data.
req.session.reload(function(err) {
// session updated
})
req.session.save(function(err) {
// session saved
})
Updates the .maxAge property. Typically this is
not necessary to call, as the session middleware does this for you.
Each session has a unique cookie object accompany it. This allows
you to alter the session cookie per visitor. For example we can
set req.session.cookie.expires to false to enable the cookie
to remain for only the duration of the user-agent.
Alternatively req.session.cookie.maxAge will return the time
remaining in milliseconds, which we may also re-assign a new value
to adjust the .expires property appropriately. The following
are essentially equivalent
var hour = 3600000
req.session.cookie.expires = new Date(Date.now() + hour)
req.session.cookie.maxAge = hour
For example when maxAge is set to 60000 (one minute), and 30 seconds
has elapsed it will return 30000 until the current request has completed,
at which time req.session.touch() is called to reset req.session.maxAge
to its original value.
req.session.cookie.maxAge // => 30000
Every session store must implement the following methods
.get(sid, callback).set(sid, session, callback).destroy(sid, callback)Recommended methods include, but are not limited to:
.length(callback).clear(callback)For an example implementation view the connect-redis repo.
FAQs
Simple session middleware for Express
We found that express-session demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 2 open source maintainers collaborating on the project.
Did you know?
Socket for GitHub automatically highlights issues in each pull request and monitors the health of all your open source dependencies. Discover the contents of your packages and block harmful activity before you install or update your dependencies.
Security News
Research
An advanced npm supply chain attack is leveraging Ethereum smart contracts for decentralized, persistent malware control, evading traditional defenses.
Security News
Research
Attackers are impersonating Sindre Sorhus on npm with a fake 'chalk-node' package containing a malicious backdoor to compromise developers' projects.
Security News
The npm package for the LottieFiles Player web component was hit with a supply chain attack after a software engineer's npmjs credentials were compromised.