express-jwt

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.

README

express-jwt

Middleware that validates JsonWebTokens and set req.user.

This module lets you authenticate HTTP requests using JWT tokens, in your Node.js applications. JWT tokens 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 token. 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 });

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...');
  }
});

Related Modules

• jsonwebtoken — JSON Web Token sign and verification

Tests

$ npm install
$ npm test

Credits

• Matias Woloski

License

The MIT License

Copyright (c) 2013 Auth0 <http://auth0.com>