jwt npm

JSON Web Token is a way of securely transmitting information between two parties. It is widely used in web applications for authentication and authorization purposes. In this article, we make a project that demonstrates a basic implementation of JWT in a Node.js application. The application features user registration with password hashing, login and generating tokens.

Prerequisites:

Features of JWT

JSON Format: The token is represented as a JSON object, making it easy to work with in web environments.
Security: JWTs can be signed using cryptographic algorithms, such as HMAC. This signature ensures the integrity of the data and helps prevent unauthorized modifications.
Compactness: It stores essential information within the token, making it lightweight and efficient to transmit.
Validity: JWTs can include an expiration time which limits their validity period.
Customizable: JWTs can include additional user data or permissions through custom claims.

Approach

Import the required modules and configure the Express application to use JSON parsing.
Implement a register function to hash passwords using bcrypt and store user details.
Implement a login function to verify user credentials and generate a JWT upon successful authentication.
Start the Express server and test user registration and login functionality with JWT token generation.
Initialize Node.js project and install express, jsonwebtoken, and bcryptjs.

Steps to Create Application

Step 1: Create a root directory and navigate to it using the following command.

mkdir jwt-demo-app
cd jwt-demo-app

Step 2 : Initialize your project by this command.

npm init -y

Step 3: Install the necessary packages/libraries in your project using the following commands.

npm install express jsonwebtoken bcryptjs

Project Structure:
Project Structure

The updated dependencies in package.json file will look like:

"dependencies": {
    "bcryptjs": "^2.4.3",
    "express": "^4.19.2",
    "jsonwebtoken": "^9.0.2"
  }

Example: Implementation to show the use of JWT with an example.

JavaScript

// app.js 

import express from 'express';
import jwt from 'jsonwebtoken';
import bcrypt from 'bcryptjs';


const app = express();
const PORT = 3000;
const SECRET_KEY = 'xxxx-xxxx';

app.use(express.json());

// This will act as our 'database'
let users = [];

// Register route
async function register(username, email, password) {
    // Hash the password
    const hashedPassword = await bcrypt.hash(password, 8);
    // Save the user
    users.push({ username, password: hashedPassword, email });
    console.log('User registered Successfully.');
    return true;
}

// Login route
async function login(email, password) {
    // Find the user
    const user = users.find(user => user.email == email);
    if (!user) {
        console.log('User not found.')
        return null;
    }
    // Check the password
    const isMatch = await bcrypt.compare(password, user.password);
    if (!isMatch) {
        console.log('Invalid credentials');
        return null;
    }
    console.log('User Details', user, '\n')
    // Generate a JWT
    const token = jwt.sign(
        { email },
        SECRET_KEY,
        { expiresIn: '1h' });
    console.log('Token', token, '\n')
    return token;
}

// register a user 
register('Sandeep', 'ex@gmail.com', 'exm123')

setTimeout(() => {
    login('ex@gmail.com', 'exm123')
}, 5000); // after 5 second login 

app.listen(PORT, () => {
    console.log(`Server is running  ${PORT}`);
});

Step to Run Application: Run the application using the following command from the root directory of the project

node .\app.js

Output: Your project will be shown in the URL http://localhost:3000/

JWT Output

Tags:

#Node-npm #Node.js #Web Technologies

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