TL;DR: Vuejs is a progressive JavaScript framework for building user interfaces on the web. It was launched shortly after ReactJS and over time, lots of developers started adopting it in their daily work. In fact, with the launch of Vuejs 2.0, the adoption and usage worldwide skyrocketed. Currently, Vuejs has over 49,000 stars on GitHub. In this tutorial, I'll show you how easy it is to build a web application with Vuejs 2 and add authentication to it. Check out the repo to get the code.

Vuejs was developed by Evan You, an ex-Google software engineer. Just before launching Vuejs 2.0, he started to work on Vue.js full time and as a result, Vue.js 2 is now significantly lighter, smaller in size and faster. Currently, many popular products use Vuejs to build their user interfaces. Such platforms include Laravel Spark, Grammarly, Statamic, Laracasts and more. There is a comprehensive list of projects using Vuejs on Github. Vuejs 2's documentation is very detailed, and there is a vibrant community of users.

Vuejs 2, Angular 2 and React

Vuejs was inspired by AngularJS in it's early days of development, thus making some of its syntax look very similar to AngularJS, e.g v-show , v-if and v-for . Angular 2 came to the scene with a completely new framework in terms of API design, underlying language and many addons, which was initially disturbing for a lot of developers. Now Vuejs 2, despite being a full rewrite made its API largely compatible with Vuejs 1.0, thus making it super easy for developers to transition from Vuejs 1.0 to 2.0. Whoop! Whoop!

Vuejs 2.0 comes bundled with some major changes:

The rendering layer is now based on a lightweight virtual-DOM implementation, Snabbom

Detection of static class names and attributes so that they are never diffed after the initial render

Detection of sub trees without dynamic bindings and hoisting them out of the render function, which as a result leads to diff skipping on each re-render.

It supports server-side rendering with client-side hydration. React and Angular 2 also provides server-side rendering.

Support for JSX. The template syntax is still available for use, but you can always drop down to the virtual-DOM layer whenever you feel constrained by the use of templates.

The template-to-virtual-DOM compiler and the runtime can be separated, so you can pre-compile templates and ship your app with only the runtime, which is less than 12kb min+gzip.

AngularJS(Angular 1) uses two-way binding between scopes, while Vue enforces a one-way data flow between components.

Vuejs 2 and Angular 2 are similar in a way because they both offer component-based systems.

React and Vue.js are also similar in many ways. They both:

Utilize a virtual DOM.

Provide composable view components.

Have a core library & have sister libraries for handling state, routing, network requests, e.t.c.

Note: If you are coming from jQuery and new to Vuejs, here is a refresher to bring you up to date.

Enter Performance Profiling

Vue.js and React utilize virtual DOM, but Vue's virtual DOM implementation allows rendering of UI to be faster than that of React, because it involves less overhead. Let's look at some performance statistics done by the Vue.js team. Check out the repo here.

This benchmark was run 20 times with results from the best runs on a 2014 MacBook Air.

Vue, React Metrics

By default, React triggers a re-render of an entire component subtree when state changes. To avoid unecessary re-rendering, you have to manually implement shouldComponentUpdate . In Vuejs, a component’s dependencies are automatically tracked during its render, so the system knows precisely which components actually need to re-render.

According to this benchmark, Vue 2's app size is smaller than Angular 2.

Understanding Key Concepts in Vuejs 2

Vuejs 2 is similar to React and Angular 2 in a few ways. There are few key concepts that will help you get started easily. I'll give a basic overview of these concepts to nourish your understanding of Vuejs. They are:

Directives

Components

Template/JSX

You can decide to use Vuejs 2 by simply invoking methods on a Vue instance or go the component-composing route.

<div id="app"> <p>{{ message }}</p> </div>

var app = new Vue({ el: '#app', data: { message: 'Hello, it is this easy!' } })

The result of the code above on the browser will be Hello, it is this easy!. The value of any property in the data object within a new Vue instance will be rendered to the DOM easily. The curly braces are used to display the property on the web page.

Directives

It's very easy to toggle the display of items on a web page with inbuilt directives such as v-if , v-show like so:

<div id="app"> <p v-if="visible()">{{ message }}</p> </div>

var app = new Vue({ el: '#app', data: { message: 'Hello, it is this easy!' }, methods: { visible: function() { return true; } } });

If for any reason, the visible function returns false, the paragraph would not be displayed on the web page. What about iterations and loops? Check out the code below

<div id="app"> <ol> <li v-for="item in items"> {{ item.name }} </li> </ol> </div>

var app = new Vue({ el: '#app', data: { items: [ { name: 'Prosper Otemuyiwa' }, { name: 'Goodness Kintakunte' }, { name: 'Lynda' } ] } });

On the page, it will simply display:

Prosper Otemuyiwa Goodness Kintakunte Lynda

Components

Vuejs 2 also leverages components. It allows you to build large applications composed of small, self-contained smaller components.

An example of a component is an HTML5 tag, say <header> . A header can have attributes, it can be styled and also possess its own behaviour. In Vuejs 2, you'll be able to build your own custom component by registering it like so:

Vue.component('app-nav', { template: "<li>This is the application's navbar</li>" })

Then, you can use it in another component like so:

<div> <app-nav></app-nav> </div>

So, your component will now be <app-nav></app-nav> .

Vuejs 2 provides some methods that are triggered at various points from creating a component up until the component is destroyed. This is called the Instance Lifecycle, also known as the Component's Lifecyle. Each Vue instance goes through a series of initialization steps when it is created - for example, it needs to set up data observation, compile the template, mount the instance to the DOM, and update the DOM when data changes. So you can execute custom logic in these hooks. These lifecycle hooks are beforeCreate , created , beforeMount , mounted , beforeUpdate , updated , activated , deactivated , beforeDestroy and destroyed .

Vuejs 2 Lifecycle hooks

beforeCreate() : This method is called synchronously after the Vue instance has just been initialized, before data observation and event/watcher setup.

: This method is called synchronously after the Vue instance has just been initialized, before data observation and event/watcher setup. created() : This method is called synchronously after the Vue instance is created. Data observation, computed properties, methods and event callbacks have already been set up at this stage but the mounting phase has not started yet.

: This method is called synchronously after the Vue instance is created. Data observation, computed properties, methods and event callbacks have already been set up at this stage but the mounting phase has not started yet. beforeMount() : This method is called right before the component is mounted. So it is called before the render method is executed.

: This method is called right before the component is mounted. So it is called before the method is executed. mounted() : This method is called after the component has just been mounted.

: This method is called after the component has just been mounted. beforeUpdate() : This method is called when the data changes, before the virtual DOM is re-rendered and patched.

: This method is called when the data changes, before the virtual DOM is re-rendered and patched. updated() : This method is called after a data change causes the virtual DOM to be re-rendered and patched.

: This method is called after a data change causes the virtual DOM to be re-rendered and patched. activated() : This method is called when a kept-alive component is activated.

: This method is called when a kept-alive component is activated. deactivated() : This method is called when a kept-alive component is deactivated.

: This method is called when a kept-alive component is deactivated. beforeDestroy() : This method is called right before a Vue instance or component is destroyed. At this stage the instance is still fully functional.

: This method is called right before a Vue instance or component is destroyed. At this stage the instance is still fully functional. destroyed() : This method is called after a Vue instance or component has been destroyed. When this hook is called, all directives of the Vue instance have been unbound, all event listeners have been removed, and all child Vue instances have also been destroyed.

Vuejs 2 possess some built-in components such as component , transition , transition-group , keep-alive and slot . You can take advantage of these components in your app. Check out how to use them.

Props

Props is the short form for properties . Properties are attributes of a component. In fact, props are how components talk to each other. A tag in HTML such as <img> has an attribute, a.k.a prop called src that points to the location of an image.

In Vue.js 2, you can pass data from the parent scope into child components. A typical example is this:

Vue.component('tag-list', { props: ['item'], template: '<li></li>' }) var app = new Vue({ el: '#app', data: { tagList: [ { tag: '5kbae' }, { tag: 'Based on Logistics' }, { tag: 'Image management' } ] } })

<div id="app"> <ol> <tag-list v-for="list in tagList" v-bind:item="list"></tag-list> </ol> </div>

It will display these items on the web page like so:

5kbae Based on Logistics Image management

Template / JSX

Vue.js 2 uses an HTML-based template syntax that allows you to declaratively bind the rendered DOM to the underlying Vue instance’s data. All Vue.js templates are valid HTML that can be parsed by spec-compliant browsers and HTML parsers.

You can also decide to use JSX. JSX is the combination of HTML and JavaScript code in the same file. The browser is not meant to understand it. It must first be transpiled into standard JavaScript before the browser can understand. An example of JSX usage in Vuejs is:

data: { text: 'Hello world' }, render (h) { return ( <div id='message'> { this.text } </div> ); }

Now, by default, Vue doesn't support JSX, but with the help of babel-plugin-transform-vue-jsx we can use JSX with Vue. Oh, the ecosystem should be thanked for this great tool. Whoop! Whoop!

With Vue 2, you can use the render function to create a reactive element. And you can use JSX in it like so:

new Vue({ el: '#app', data: { msg: 'Click to see the message.' }, methods: { hello () { alert('This is the message.') } }, render: function render(h) { return ( <span class={{ 'my-class-3': true }} style={{ cursor: 'pointer' }} on-click={ this.hello } > { this.msg } </span> ) } });

Can you see the power of JSX manifesting itself in Vue? Awesome, you can check out more information on JSX in Vue here.

Next, let's build an application with Vuejs 2.

Our App: The Ultimate Startup Battle Ground

The app we will build today is called The Ultimate Startup Battle Ground . Several startups are springing up all over the world. These startups are coming up with innovative technology but have limited funds. Our app hopes to alleviate the issue of funding by providing an up-to-date list of startup battles all over the world with details of sponsors and seed fund amount. The Ultimate Startup Battle Ground app will display a list of startup battles to the general public.

Interested startup founders can get hold of this list and ensure their team does not miss out on it. However, the app will also provide a list of secret startup battles. This list will only be accessible to registered members.

Note: The secret startup battles have bigger sponsors. How dare you miss that? Not gonna happen!

Build The Back-End

Let's build an API to serve the list of startup battles to our app. We'll quickly build the API with Node.js. The API is simple. This is what we need:

An endpoint to serve public startup battles - /api/battles/public .

. An endpoint to serve secret startup battles - /api/battles/private .

. Secure the endpoint that serves secret startup battles, so that it can only be accessed by registered users.

Go ahead and fetch the Node.js backend from GitHub.

Note: We'll be securing the backend with Auth0, so make sure you have an account already or sign up for one.

Your server.js should look like this:

'use strict'; const express = require('express'); const app = express(); const jwt = require('express-jwt'); const jwks = require('jwks-rsa'); const cors = require('cors'); const bodyParser = require('body-parser'); app.use(bodyParser.json()); app.use(bodyParser.urlencoded({ extended: true })); app.use(cors()); const authCheck = jwt({ secret: jwks.expressJwtSecret({ cache: true, rateLimit: true, jwksRequestsPerMinute: 5, jwksUri: "https:///.well-known/jwks.json" }), // This is the identifier we set when we created the API audience: '{YOUR-API-AUDIENCE-ATTRIBUTE}', issuer: "https://{YOUR-AUTH0-DOMAIN}.auth0.com/", algorithms: ['RS256'] }); app.get('/api/battles/public', (req, res) => { let publicBattles = [ // Array of public battles ]; res.json(publicBattles); }) app.get('/api/battles/private', authCheck, (req,res) => { let privateBattles = [ // Array of private battles ]; res.json(privateBattles); }) app.listen(3333); console.log('Listening on localhost:3333');

server.js

Check out the full server.js file here.

Note: Your YOUR-AUTH0-DOMAIN should be replaced with your auth0 domain.

Your package.json file should look like this:

{ "name": "startup-battle", "version": "0.0.1", "description": "", "main": "server.js", "scripts": { "test": "echo \"Error: no test specified\" && exit 1", "start": "node server.js", "dev": "nodemon server.js" }, "author": "Auth0", "license": "MIT", "dependencies": { "body-parser": "^1.15.2", "cors": "^2.8.1", "express": "^4.14.0", "express-jwt": "^3.4.0", "jwks-rsa": "^1.1.1" } }

Note: Make sure you have nodemon installed globally.

package.json

Once you have cloned the project, run an npm install , then use postman to serve your routes like so:

API serving public startup battles

API serving private startup battles

The public startup battles endpoint should be http://localhost:3333/api/battles/public .

The private startup battles endpoint should be http://localhost:3333/api/battles/private .

Don't worry about the middleware in charge of securing our endpoint for now. We'll deal with that later. Now, let's build our frontend with Vuejs 2.

Build The Front-End With Vuejs 2

In the early days of Vuejs, there was no particular recommended tool or common way to set up a Vuejs app. However, there is a tool now for scaffolding your Vuejs apps. It's called the Vuejs CLI tool. It's being maintained by the Vuejs team.

Go ahead and install the vue-cli tool globally like so:

npm install -g vue-cli

You will be greeted with a series of questions

After installing globally, go ahead and scaffold a new Vuejs 2 app like so:

vue init webpack ultimate-startup-battle

Note: In this context, webpack is a template. You can actually select the template you want vue-cli to scaffold your app with. Another alternative is to use browserify . Check out the list of templates here.

Move into the new directory, ultimate-startup-battle and run npm install to install all the dependencies required for your app.

Now run npm run dev from your terminal to start up your app. It should automatically open up your web browser at http://localhost:8080 and serve your new app.

Let's check out the structure of our newly scaffolded app.

ultimate-startup-battle/ build/ - All build files are here config/ - All environment config files are here node_modules/ - All the packages required for the vuejs app resides here src/ - assets - All assets reside here - components - All our Vue components resides here - router - Our router is defined here - App.vue - The Parent component - main.js - Starting point for our app where the router, template and App component are bound to the root app div static/ - contains static files .babelrc .editorconfig .eslintignore .eslintrc.js .gitignore .postcssrc.js index.html - Index file that declares the root div where the App component is been bound to package.json - File that contains the names of all the packages residing in node_modules folder README.md node_modules/ - All the packages required for the react app resides here package.json - File that contains the names of all the packages residing in node_modules folder

We will work with this structure but make some few modifications.

Note: We are not writing any tests for this application. It's out of the scope of this tutorial. So during the installation, I opted out by choosing the no option.

Make the following modifications like so:

Create a privateBattles.vue file inside the components directory. This component will take care of fetching the private startup battles and displaying them to the user.

file inside the directory. This component will take care of fetching the private startup battles and displaying them to the user. Create a publicBattles.vue file inside the components directory. This component will take care of fetching the public startup battles and displaying them to the user.

file inside the directory. This component will take care of fetching the public startup battles and displaying them to the user. Create a AppNav.vue file inside the components directory. This component will be in charge of our navigation throughout the app.

file inside the directory. This component will be in charge of our navigation throughout the app. Create a folder called utils . This will house our helper functions.

Fetch the API Data

The first thing we need to do is to fetch the API data from our Node backend to display in our app. Make sure the Node server is running.

Let's create a helper file to handle fetching the API. Create a battles-api.js file inside the utils directory.

Open up the file and add code to it like so:

import axios from 'axios'; const BASE_URL = 'http://localhost:3333'; export {getPublicStartupBattles, getPrivateStartupBattles}; function getPublicStartupBattles() { const url = `${BASE_URL}/api/battles/public`; return axios.get(url).then(response => response.data); } function getPrivateStartupBattles() { const url = `${BASE_URL}/api/battles/private`; return axios.get(url).then(response => response.data); }

battles-api.js

Note: Install axios in your app by running npm install axios --save .

We are using a very good promise based http client, axios. An alternative for this is superagent.

In the getPublicStartupBattles and getPrivateStartupBattles functions, axios fetches data from the API endpoints. Then we do this: export {getPublicStartupBattles, getPrivateStartupBattles}; to make them ready for use in our components.

Build the Nav Component

The AppNav.vue file is our Nav component. Go ahead and add code to it like so:

<template> <nav class="navbar navbar-default"> <div class="navbar-header"> <router-link to="/" class="navbar-brand"> The Ultimate Startup Battle Ground</router-link> </div> <ul class="nav navbar-nav navbar-right"> <li> <button class="btn btn-danger log" @click="handleLogout()">Log out </button> <button class="btn btn-info log" @click="handleLogin()">Log In</button> </li> </ul> </nav> </template> <script> import { isLoggedIn, login, logout } from '../../utils/auth'; export default { name: 'app-nav', methods: { handleLogin() { login(); }, handleLogout() { logout(); }, isLoggedIn() { return isLoggedIn(); }, }, }; </script> <!-- Add "scoped" attribute to limit CSS to this component only --> <style scoped> .navbar-right { margin-right: 0px !important} .log { margin: 5px 10px 0 0; } </style>

The router-link Component from vue-router enables seamless client-side transition between routes without any page reload.

Build the PublicBattles and PrivateBattles Component

By default, these two components will look similar in functionalities. They both display data from different endpoints. Let's start with the PublicBattles component.

<template> <div> <app-nav></app-nav> <h3 class="text-center">Daily Startup Battles</h3> <hr/> <div class="col-sm-4" v-for="battle in publicBattles"> <div class="panel panel-default"> <div class="panel-heading"> <h3 class="panel-title"> {{ battle.name }} </h3> </div> <div class="panel-body"> <p><span class="badge alert-info"> Sponsor: </span> {{ battle.sponsor }} </p> <p><span class="badge alert-danger"> SeedFund: </span><strong> ${{ battle.seedFund }} </strong></p> </div> </div> </div> <div class="col-sm-12"> <div class="jumbotron text-center"> <h2>View Private Startup Battles</h2> <router-link class="btn btn-lg btn-success" to="/private-battles">Private Startup Battles</router-link> </div> </div> </div> </template> <script> import AppNav from './AppNav'; import { isLoggedIn } from '../../utils/auth'; import { getPublicStartupBattles } from '../../utils/battles-api'; export default { name: 'publicBattles', components: { AppNav, }, data() { return { publicBattles: '', }; }, methods: { isLoggedIn() { return isLoggedIn(); }, getPublicStartupBattles() { getPublicStartupBattles().then((battles) => { this.publicBattles = battles; }); }, }, mounted() { this.getPublicStartupBattles(); }, }; </script> <!-- Add "scoped" attribute to limit CSS to this component only --> <style scoped> </style>

publicBattles.vue

Let's analyze the code above. The publicBattles component is pulling data from an API, so it needs a way of holding that data. Vuejs has a data method where you can define properties to hold your data as some form of state. In the code above, we declared a publicBattles property.

The methods property also comes by default with Vuejs. In this property, you can define custom logic as functions within this property. So we defined isLoggedIn and getPublicStartupBattles functions.

In the getPublicStartupBattles method, we call the getPublicStartupBattles method we exported from the battles-api.js helper file and set state as seen below:

... getPublicStartupBattles() { getPublicStartupBattles().then((battles) => { this.publicBattles = battles; }); }, ...

Now, we took advantage of one of the Vuejs 2 lifecycle hooks, mounted . Whatever is defined in this method is applied just after a component is mounted on the browser screen. So, we invoked the getPublicStartupBattles method in the hook as seen below:

... mounted() { this.getPublicStartupBattles(); } ...

All we are trying to do is tell Vuejs to load the data from the API just after the publicBattles component gets rendered.

Note: You can add a loading indicator or spinner to present to the user while the data is been loaded from the API. This avoids flashing of blank screens. Check out vuejs transition for loading data.

We imported the AppNav component and registered it under the components property. The name property has a value of publicBattles . What that simply means is this. If we need to use this component in a template, then we would have it as <publicBattles></publicBattles> .

Let's take a good look at what is enclosed in the <template> tag. This is what is rendered on the screen.

We looped through the publicBattles property which is now an array with the help of the v-for inbuilt directive to display the contents on the screen.

<div class="col-sm-4" v-for="battle in publicBattles"> <div class="panel panel-default"> <div class="panel-heading"> <h3 class="panel-title"> {{ battle.name }} </h3> </div> <div class="panel-body"> <p><span class="badge alert-info"> Sponsor: </span> {{ battle.sponsor }} </p> <p><span class="badge alert-danger"> SeedFund: </span><strong> ${{ battle.seedFund }} </strong></p> </div> </div> </div>

... data() { return { publicBattles: '', }; }, ...

That's the publicBattles property right there. Vuejs automatically binds it to the DOM. So, we can just use it in the <template> tag.

Now, let's build the PrivateBattles component in the same way:

<template> <div> <app-nav></app-nav> <h3 class="text-center">Secret Startup Battles</h3> <hr/> <div class="col-sm-4" v-for="battle in privateBattles"> <div class="panel panel-danger"> <div class="panel-heading"> <h3 class="panel-title"> {{ battle.name }} </h3> </div> <div class="panel-body"> <p><span class="badge alert-info"> Sponsor: </span> {{ battle.sponsor }} </p> <p><span class="badge alert-danger"> SeedFund: </span><strong> ${{ battle.seedFund }} </strong></p> </div> </div> </div> <div class="col-sm-12"> <div class="jumbotron text-center"> <h2>View Public Startup Battles</h2> <router-link class="btn btn-lg btn-success" to="/"> Public Startup Battles </router-link> </div> </div> </div> </template> <script> import AppNav from './AppNav'; import { isLoggedIn } from '../../utils/auth'; import { getPrivateStartupBattles } from '../../utils/battles-api'; export default { name: 'privateBattles', components: { AppNav, }, data() { return { privateBattles: '', }; }, methods: { isLoggedIn() { return isLoggedIn(); }, getPrivateStartupBattles() { getPrivateStartupBattles().then((battles) => { this.privateBattles = battles; }); }, }, mounted() { this.getPrivateStartupBattles(); }, }; </script> <!-- Add "scoped" attribute to limit CSS to this component only --> <style scoped> </style>

privateBattles.vue

Give yourself a pat on the back because you have successfully created the AppNav , PublicBattles , and PrivateBattles components. Whoop! Whoop!

We need to take care of one more thing so that our app can function. Routing!!!

Build the Router

Open up src/router/index.js file, this is where the vue router is defined. So modify the code like so:

import Vue from 'vue'; import Router from 'vue-router'; import PrivateBattles from '@/components/privateBattles'; import PublicBattles from '@/components/publicBattles'; Vue.use(Router); export default new Router({ mode: 'history', routes: [ { path: '/', name: 'PublicBattles', component: PublicBattles, }, { path: '/private-battles', name: 'PrivateBattles', component: PrivateBattles, }, ], });

index.js

Each route has a path, name and the component to be rendered when that route is invoked by the user. By the ways, we already imported the components at the top of the file.

import Vue from 'vue'; import Router from 'vue-router'; import PrivateBattles from '@/components/privateBattles'; import PublicBattles from '@/components/publicBattles';

Just a few things before we check our application in the browser:

Open up index.html in the root directory and add bootstrap. Now the content of the html file should look like this:

<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>startupbattle</title> <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css"> </head> <body> <div id="app"></div> <!-- built files will be auto injected --> </body> </html>

Feel free to check out your application in the browser. Right now, you should have something like this:

Homepage

Private Battles Page

Adding Authentication to Your Vuejs 2 App

The majority of the apps we use on a daily basis have a means of authenticating users. I'll show you how to easily add authentication to our Vuejs 2 application. We'll use Auth0 as our authentication service.

Auth0 allows us to issue JSON Web Tokens (JWTs). If you don't already have an Auth0 account, sign up for a free one now.

Auth0 offers a generous free tier to get started with modern authentication.

Login to your Auth0 management dashboard and let's create a new Auth0 API. To do so, click on the APIs menu item and then the Create API button. You will need to give your API a name and an identifier. The name can be anything you choose, so make it as descriptive as you want. The identifier will be used to identify your API, this field cannot be changed once set. For our example, I'll name the API Startup Battle API and for the identifier I'll set it as http://startupbattle.com. We'll leave the signing algorithm as RS256 and click on the Create API button.

Creating the Startup battle API

Next, let's define some scopes for our API. Scopes allow us to manage access to our API. We can define as few or as many scopes as we want. For our simple example, we'll just create a single scope that will grant users full access to the API.

Locate Scopes bar

Adding scope

Secure The Node API

We need to secure the API so that the private battles endpoint will only be accessible to authenticated users. We can secure it easily with Auth0.

Open up your server.js file and add the authCheck middleware to the private battles endpoint like so:

app.get('/api/battles/private', authCheck, (req,res) => { let privateBattles = [ // Array of private battles ]; res.json(privateBattles); }) app.listen(3333); console.log('Listening on localhost:3333');

Try accessing the http://localhost:3333/api/battles/private endpoint again from Postman. You should be denied access like so:

Unauthorized Access

Next, let's add authentication to our front-end.

Adding Authentication to our Vuejs 2 Front-end

We'll create an authentication helper to handle everything about authentication in our app. Go ahead and create an auth.js file inside the utils directory.

Before we add code, you need to install jwt-decode and auth0-js node package like so:

npm install jwt-decode auth0-js --save

Open up the auth.js file and add code to it like so:

import decode from 'jwt-decode'; import axios from 'axios'; import auth0 from 'auth0-js'; import Router from 'vue-router'; import Auth0Lock from 'auth0-lock'; const ID_TOKEN_KEY = 'id_token'; const ACCESS_TOKEN_KEY = 'access_token'; const CLIENT_ID = '{AUTH0_CLIENT_ID}'; const CLIENT_DOMAIN = '{AUTH0_DOMAIN}'; const REDIRECT = 'YOUR_CALLBACK_URL'; const SCOPE = '{SCOPE}'; const AUDIENCE = 'AUDIENCE_ATTRIBUTE'; var auth = new auth0.WebAuth({ clientID: CLIENT_ID, domain: CLIENT_DOMAIN }); export function login() { auth.authorize({ responseType: 'token id_token', redirectUri: REDIRECT, audience: AUDIENCE, scope: SCOPE }); } var router = new Router({ mode: 'history', }); export function logout() { clearIdToken(); clearAccessToken(); router.go('/'); } export function requireAuth(to, from, next) { if (!isLoggedIn()) { next({ path: '/', query: { redirect: to.fullPath } }); } else { next(); } } export function getIdToken() { return localStorage.getItem(ID_TOKEN_KEY); } export function getAccessToken() { return localStorage.getItem(ACCESS_TOKEN_KEY); } function clearIdToken() { localStorage.removeItem(ID_TOKEN_KEY); } function clearAccessToken() { localStorage.removeItem(ACCESS_TOKEN_KEY); } // Helper function that will allow us to extract the access_token and id_token function getParameterByName(name) { let match = RegExp('[#&]' + name + '=([^&]*)').exec(window.location.hash); return match && decodeURIComponent(match[1].replace(/\+/g, ' ')); } // Get and store access_token in local storage export function setAccessToken() { let accessToken = getParameterByName('access_token'); localStorage.setItem(ACCESS_TOKEN_KEY, accessToken); } // Get and store id_token in local storage export function setIdToken() { let idToken = getParameterByName('id_token'); localStorage.setItem(ID_TOKEN_KEY, idToken); } export function isLoggedIn() { const idToken = getIdToken(); return !!idToken && !isTokenExpired(idToken); } function getTokenExpirationDate(encodedToken) { const token = decode(encodedToken); if (!token.exp) { return null; } const date = new Date(0); date.setUTCSeconds(token.exp); return date; } function isTokenExpired(token) { const expirationDate = getTokenExpirationDate(token); return expirationDate < new Date(); }

In the code above, we are using Auth0's Login Page in the login method and passed in our credentials.

The auth0 package calls the Auth0's authorize endpoint. With all the details we passed to the method, our client app will be validated and authorized to perform authentication. You can learn more about the specific values that can be passed to the authorize method here.

The parameters that you do not have yet are the {YOUR-AUTH0-CLIENT-ID} and the {YOUR-CALLBACK-URL} . This will be an Auth0 application that will hold your users. When you created your API, Auth0 also created a test application which you can use. Additionally, you can use any existing Auth0 application found in Applications section of your management dashboard.

Check the Test panel of your API from the dashboard. You'll see the test application like so:

Startup API Application

Now, go to the Applications area and check for the test application. You should see it in your list of applications like so:

Open the application and change the Appication Type from Non Interactive Application to Single Page Application .

Copy the CLIENT ID and replace it with the value of YOUR-AUTH0-CLIENT-ID in the login URL. Replace your callback url with http://localhost:8080/callback .

We also checked whether the token has expired via the getTokenExpirationDate and isTokenExpired methods. The isLoggedIn method returns true or false based on the presence and validity of a user id_token .

We imported the Vue router and created an instance of it. We need it for redirection after login and logout.

Finally, we implemented a middleware, the requireAuth method. We'll use this method to protect the /private-battles route from being accessed for non-loggedIn users.

Let's go update the AppNav component to hide/show the login and logout buttons based on the user's authentication status.

Now, your AppNav component should look like this:

<template> <nav class="navbar navbar-default"> <div class="navbar-header"> <router-link to="/" class="navbar-brand"> The Ultimate Startup Battle Ground</router-link> </div> <ul class="nav navbar-nav navbar-right"> <li> <button class="btn btn-danger log" v-show="isLoggedIn()" @click="handleLogout()">Log out </button> <button class="btn btn-info log" v-show="!isLoggedIn()" @click="handleLogin()">Log In</button> </li> </ul> </nav> </template> <script> import { isLoggedIn, login, logout } from '../../utils/auth'; export default { name: 'app-nav', methods: { handleLogin() { login(); }, handleLogout() { logout(); }, isLoggedIn() { return isLoggedIn(); }, }, }; </script> <!-- Add "scoped" attribute to limit CSS to this component only --> <style scoped> .navbar-right { margin-right: 0px !important} .log { margin: 5px 10px 0 0; } </style>

AppNav.vue

We imported login , logout and isLoggedIn functions from the auth helper file. Then, we attached the login() and logout() functions to the login and logout buttons respectively.

Open up the PublicBattles Component and modify it like so:

<template> <div> <app-nav></app-nav> <h3 class="text-center">Daily Startup Battles</h3> <hr/> <div class="col-sm-4" v-for="battle in publicBattles"> <div class="panel panel-default"> <div class="panel-heading"> <h3 class="panel-title"> {{ battle.name }} </h3> </div> <div class="panel-body"> <p><span class="badge alert-info"> Sponsor: </span> {{ battle.sponsor }} </p> <p><span class="badge alert-danger"> SeedFund: </span><strong> ${{ battle.seedFund }} </strong></p> </div> </div> </div> <div class="col-sm-12"> <div class="jumbotron text-center" v-if="isLoggedIn()"> <h2>View Private Startup Battles</h2> <router-link class="btn btn-lg btn-success" to="/private-battles">Private Startup Battles</router-link> </div> <div class="jumbotron text-center" v-else> <h2>Get Access to Private Startup Battles by Logging In</h2> </div> </div> </div> </template> <script> import AppNav from './AppNav'; import { isLoggedIn } from '../../utils/auth'; import { getPublicStartupBattles } from '../../utils/battles-api'; export default { name: 'publicBattles', components: { AppNav, }, data() { return { publicBattles: '', }; }, methods: { isLoggedIn() { return isLoggedIn(); }, getPublicStartupBattles() { getPublicStartupBattles().then((battles) => { this.publicBattles = battles; }); }, }, mounted() { this.getPublicStartupBattles(); }, }; </script> <!-- Add "scoped" attribute to limit CSS to this component only --> <style scoped> </style>

publicBattles.vue

We are enabling the link to private startup battles based on the login status of a user via the isLoggedIn() method.

Add A Callback Component

We will create a new component and call it callback.vue . This component will be activated when the localhost:8080/callback route is called and it will process the redirect from Auth0 and ensure we recieved the right data back after a successful authentication. The component will store the access_token and id_token .

callback.vue

<template> </template> <script> import { setIdToken, setAccessToken } from '../../utils/auth'; export default { name: '', mounted() { this.$nextTick(() => { setAccessToken(); setIdToken(); window.location.href = '/'; }); }, }; </script>

Once a user is authenticated, Auth0 will redirect back to our application and call the /callback route. Auth0 will also append the id_token as well as the access_token to this request, and our Callback component will make sure to properly process and store those tokens in localStorage. If all is well, meaning we recieved an id_token , access_token , and verified the nonce , we will be redirected back to the / page and will be in a logged in state.

Add some values to Auth0 Dashboard

Just before you try to log in or sign up, head over to your Auth0 dashboard and add http://localhost:8080/callback to the Allowed Callback URLs and http://localhost:8080 to Allowed Origins (CORS).

Secure The Private Battles Route

We need to ensure that no one can go to the browser and just type /private-battles to access the private battles route.

Open up router/index.js and modify it to import the requireAuth function and also add a beforeEnter property with a value of requireAuth to the /private-battles route like so:

import Vue from 'vue'; import Router from 'vue-router'; import PrivateBattles from '@/components/privateBattles'; import PublicBattles from '@/components/publicBattles'; import { requireAuth } from '../../utils/auth'; Vue.use(Router); export default new Router({ routes: [ { path: '/', name: 'PublicBattles', component: PublicBattles, }, { path: '/private-battles', name: 'PrivateBattles', beforeEnter: requireAuth, component: PrivateBattles, }, ], });

index.js

One more thing. Now, let's register the /callback route in our routes file like so:

import Vue from 'vue'; import Router from 'vue-router'; import PrivateBattles from '@/components/privateBattles'; import PublicBattles from '@/components/publicBattles'; import Callback from '@/components/callback'; import { requireAuth } from '../../utils/auth'; Vue.use(Router); export default new Router({ mode: 'history', routes: [ { path: '/', name: 'PublicBattles', component: PublicBattles, }, { path: '/private-battles', name: 'PrivateBattles', beforeEnter: requireAuth, component: PrivateBattles, }, { path: '/callback', component: Callback, }, ], });

Now, try to log in.

Lock Login Widget

For the first time, the user will be shown a user consent dialog that will show the scope available. Once a user authorizes, it goes ahead to login the user and give him access based on the scopes.

User presented with an option to authorize

Note: Since we are using localhost for our domain, once a user logs in the first time, subsequent logins will not need a user consent authorization dialog. This consent dialog will not be displayed if you are using a non-localhost domain, and the application is a first-party application.

Logged In, but unauthorized to see the Private Startup Battle

We have successfully logged in but the content of the private startup battle is not showing up and in the console, we are getting a 401 Unauthorized error. Why?

It's simple! We secured our endpoint earlier, but right now we are not passing the JWT to the backend yet. We need to send the JWT along with our request as a header to enable the secured endpoint's recognition of the logged-in user.

Updating the Auth & Battles API helper

Go ahead and open up the utils/battles-api.js file. We will tweak the getPrivateStartupBattles function a bit. Currently, it initiates a GET request only to fetch data from the API.

Now, we will pass an option to send an Authorization header with a Bearer access_token along with the GET request like so:

import { getAccessToken } from './auth'; function getPrivateStartupBattles() { const url = `${BASE_URL}/api/battles/private`; return axios.get(url, { headers: { Authorization: `Bearer ${getAccessToken()}` }}).then(response => response.data); }

The /api/battles/private endpoint will receive the token in the header and validate the user. If it is valid, the content will be provided to us.

Now, try to log in again.

Everything should work fine. Pat yourself on the back. You have just successfully built a Vuejs 2 app and added authentication to it!

Conclusion

Vuejs 2 is a lightweight, fast and awesome library for building user interfaces. Its learning curve is gentle and its API is not complex to understand. It has a fast growing community and there are many components available to the public for different functionalities.

In addition, Auth0 can help secure your Vuejs 2 apps with more than just username-password authentication. It provides features like multifactor auth, anomaly detection, enterprise federation, single sign on (SSO), and more. Sign up today so you can focus on building features unique to your app.