What is express-jwt?
The express-jwt package is a middleware for Express.js that allows you to validate JSON Web Tokens (JWTs) in your HTTP requests. It is commonly used for securing routes and ensuring that only authenticated users can access certain endpoints.
What are express-jwt's main functionalities?
JWT Validation
This feature allows you to validate JWTs in incoming requests. The middleware checks the token's validity and ensures it is signed with the correct secret key and algorithm.
const express = require('express');
const jwt = require('express-jwt');
const app = express();
const jwtMiddleware = jwt({
secret: 'your-secret-key',
algorithms: ['HS256']
});
app.use('/protected', jwtMiddleware, (req, res) => {
res.send('This is a protected route');
});
app.listen(3000, () => {
console.log('Server is running on port 3000');
});
Error Handling
This feature allows you to handle errors that occur during JWT validation. For example, you can send a 401 Unauthorized response if the token is invalid.
const express = require('express');
const jwt = require('express-jwt');
const app = express();
const jwtMiddleware = jwt({
secret: 'your-secret-key',
algorithms: ['HS256']
});
app.use('/protected', jwtMiddleware, (err, req, res, next) => {
if (err.name === 'UnauthorizedError') {
res.status(401).send('Invalid token');
} else {
next(err);
}
});
app.listen(3000, () => {
console.log('Server is running on port 3000');
});
Token Decoding
This feature allows you to decode the JWT and attach the payload to the request object. You can then access the decoded information in your route handlers.
const express = require('express');
const jwt = require('express-jwt');
const app = express();
const jwtMiddleware = jwt({
secret: 'your-secret-key',
algorithms: ['HS256'],
requestProperty: 'auth'
});
app.use('/protected', jwtMiddleware, (req, res) => {
res.send(`Hello, ${req.auth.name}`);
});
app.listen(3000, () => {
console.log('Server is running on port 3000');
});
Other packages similar to express-jwt
jsonwebtoken
The jsonwebtoken package is a popular library for creating and verifying JSON Web Tokens. Unlike express-jwt, it does not provide middleware for Express.js, but it offers more flexibility for handling tokens in various contexts.
passport-jwt
The passport-jwt package is a Passport.js strategy for authenticating with a JSON Web Token. It integrates with Passport.js, a popular authentication middleware for Node.js, and provides more comprehensive authentication solutions compared to express-jwt.
koa-jwt
The koa-jwt package is similar to express-jwt but is designed for Koa.js applications. It provides middleware for validating JWTs in Koa.js, making it a suitable alternative for developers using the Koa framework.
express-jwt
Middleware that validates JsonWebTokens and sets req.user
.
This module lets you authenticate HTTP requests using JWT tokens in your Node.js
applications. JWTs are typically used protect API endpoints, and are
often issued using OpenID Connect.
Install
$ npm install express-jwt
Usage
The JWT authentication middleware authenticates callers using a JWT.
If the token is valid, req.user
will be set with the JSON object decoded
to be used by later middleware for authorization and access control.
For example,
var jwt = require('express-jwt');
app.get('/protected',
jwt({secret: 'shhhhhhared-secret'}),
function(req, res) {
if (!req.user.admin) return res.send(401);
res.send(200);
});
You can specify audience and/or issuer as well:
jwt({ secret: 'shhhhhhared-secret',
audience: 'http://myapi/protected',
issuer: 'http://issuer' })
If the JWT has an expiration (exp
), it will be checked.
Optionally you can make some paths unprotected as follows:
app.use(jwt({ secret: 'shhhhhhared-secret'}).unless({path: ['/token']}));
This is especially useful when applying to multiple routes.
This module also support tokens signed with public/private key pairs. Instead of a secret, you can specify a Buffer with the public key
var publicKey = fs.readFileSync('/pat/to/public.pub');
jwt({ secret: publicKey });
By default, the decoded token is attached to req.user
but can be configured with the userProperty
option.
jwt({ secret: publicKey, userProperty: 'auth' });
A custom function for extracting the token from a request can be specified with
the getToken
option. This is useful if you need to pass the token through a
query parameter or a cookie. You can throw an error in this function and it will
be handled by express-jwt
.
app.use(jwt({
secret: 'hello world !',
credentialsRequired: false,
getToken: function fromHeaderOrQuerystring (req) {
if (req.headers.authorization && req.headers.authorization.split(' ')[0] === 'Bearer') {
return req.headers.authorization.split(' ')[1];
} else if (req.query && req.query.token) {
return req.query.token;
}
return null;
}
}));
Error handling
The default behavior is to throw an error when the token is invalid, so you can add your custom logic to manage unauthorized access as follows:
app.use(function (err, req, res, next) {
if (err.name === 'UnauthorizedError') {
res.send(401, 'invalid token...');
}
});
You might want to use this module to identify registered users without preventing unregistered clients to access to some data, you
can do it using the option credentialsRequired:
app.use(jwt({
secret: 'hello world !',
credentialsRequired: false
}));
Related Modules
Issue Reporting
If you have found a bug or if you have a feature request, please report them at this repository issues section. Please do not report security vulnerabilities on the public GitHub issue tracker. The Responsible Disclosure Program details the procedure for disclosing security issues.
Tests
$ npm install
$ npm test
Credits
License
The MIT License
Copyright (c) 2013 Auth0 <http://auth0.com>