Introduction

In this tutorial, we aim to guide you through the process of implementing authentication using JSON Web Tokens (JWT) in a Vue.js application. JWT is a standard method for securely transmitting information between parties as a JSON object. By the end of this tutorial, you will understand how JWT works, how to implement it in your Vue application, and how to secure your application by verifying the token.

What you will learn:
- JWT fundamentals
- Setting up JWT authentication in Vue.js
- Securing routes using JWT

Prerequisites:
- Basic understanding of Vue.js
- Basic knowledge of JavaScript
- Understanding of REST APIs and HTTP requests

Step-by-Step Guide

JWT Basics

JWT is a compact, URL-safe means of representing claims to be transferred between two parties. The claims in a JWT are encoded as a JSON object that is used as the payload of a JSON Web Signature (JWS) structure. This allows the claims to be digitally signed or integrity protected with a Message Authentication Code (MAC).

Setting up JWT Authentication in Vue.js

1. Install the necessary packages:

   To make HTTP requests, we need to install axios. You can do so by running the following command in your terminal.

   bash npm install axios

2. Creating an Authentication Service:

   Create a new file auth.service.js in your services folder. This service will be responsible for all Axios calls related to authentication.

   ```javascript
   import axios from 'axios';

   const API_URL = 'http://localhost:8080/api/auth/';

   class AuthService {
   login(user) {
   return axios
   .post(API_URL + 'signin', {
   username: user.username,
   password: user.password
   })
   .then(response => {
   if (response.data.accessToken) {
   localStorage.setItem('user', JSON.stringify(response.data));
   }
   return response.data;
   });
   }

   logout() {
   localStorage.removeItem('user');
   }

   register(user) {
   return axios.post(API_URL + 'signup', {
   username: user.username,
   email: user.email,
   password: user.password
   });
   }
   }

   export default new AuthService();
   ```

   In the above code snippet, we are making use of the axios library to send HTTP requests to our server. We are sending POST requests to the signin and signup endpoints with the user's information. If the request is successful, the server will return a JWT which we store in the browser's localStorage.

3. Securing Routes:

   You can secure your routes by adding a navigation guard to check whether the user is authenticated before accessing the route.

   ```javascript
   router.beforeEach((to, from, next) => {
   const publicPages = ['/login', '/register', '/home'];
   const authRequired = !publicPages.includes(to.path);
   const loggedIn = localStorage.getItem('user');

   if (authRequired && !loggedIn) {
   return next('/login');
   }

   next();
   })
   ```

   In the above code snippet, we are using Vue router's beforeEach hook to check if the route requires authentication and if the user is authenticated.

Summary

In this tutorial, we have learned about JSON Web Tokens, how to set up JWT authentication in a Vue.js application, and how to secure routes using JWT. For further reading, you can check out the official JWT documentation and the Vue router documentation.

Practice Exercises

1. Create a simple Vue.js application and implement JWT authentication.
2. Add a profile page that only authenticated users can access.
3. Expand the application by adding more public and private routes.

These exercises will help you practice what you've learned in this tutorial. Remember, practice is key when learning a new concept.

Happy coding!