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      How To Build a Shopping Cart with Vue 3 and Vuex


      The author selected the Open Source Initiative to receive a donation as part of the Write for DOnations program.

      Introduction

      Vue.js is a performant and progressive Javascript framework. It is a popular framework on GitHub and has an active and helpful community.

      In order to show the capabilities of the Vue web framework, this tutorial will lead you through building the shopping cart of an e-commerce app. This app will store product information and hold the products that the customer wants to buy for checkout later. To store the information, you will explore a widely used state management library for Vue.js: Vuex. This will allow the shopping cart application to persist data to a server. You will also handle asynchronous task management using Vuex.

      Once you finish the tutorial, you will have a functioning shopping cart application like the following:

      Animation of user adding and deleting products from the shopping cart application

      Prerequisites

      Step 1 — Setting Up the Application with Vue CLI

      As of version 4.5.0, Vue CLI now provides a built-in option to choose the Vue 3 preset when creating a new project. The latest version of Vue CLI allows you to use Vue 3 out of the box and to update your existing Vue 2 project to Vue 3. In this step, you will use the Vue CLI to make your project, then install the front-end dependencies.

      First, install the latest version of Vue CLI by executing the following command from the terminal:

      This will install Vue CLI globally on your system.

      Note: On some systems, installing an npm package globally can result in a permission error, which will interrupt the installation. Since it is a security best practice to avoid using sudo with npm install, you can instead resolve this by changing npm’s default directory. If you encounter an EACCES error, follow the instructions at the official npm documentation.

      Check you have the right version with this command:

      You will get output like the following:

      Output

      @vue/cli 4.5.10

      Note: If you already have the older version of Vue CLI installed globally, execute the following command from the terminal to upgrade:

      Now, you can create a new project:

      • vue create vuex-shopping-cart

      This uses the Vue CLI command vue create to make a project named vuex-shopping-cart. For more information on the Vue CLI, check out How To Generate a Vue.js Single Page App With the Vue CLI.

      Next, you will receive the following prompt:

      Output

      Vue CLI v4.5.10 ? Please pick a preset: (Use arrow keys) ❯ Default ([Vue 2] babel, eslint) Default (Vue 3 Preview) ([Vue 3] babel, eslint) Manually select features

      Choose the Manually select features option from this list.

      Next, you will encounter the following prompt to customize your Vue app:

      Output

      ... ◉ Choose Vue version ◯ Babel ◯ TypeScript ◯ Progressive Web App (PWA) Support ◉ Router ◉ Vuex ◯ CSS Pre-processors ◯ Linter / Formatter ❯◯ Unit Testing ◯ E2E Testing

      From this list, select Choose Vue version, Router, and Vuex. This will allow you to choose your version of Vue and use Vuex and Vue Router.

      Next, choose 3.x (Preview) for your version of Vue, answer no (N) to history mode, and select the option to have your configurations In dedicated config file. Finally, answer N to avoid saving the setup for a future project.

      At this point, Vue will create your application.

      After the project creation, move into the folder using the command:

      To start, you’ll install Bulma, a free, open-source CSS framework based on Flexbox. Add Bulma to your project by running the following command:

      To use Bulma CSS in your project, open up your app’s entry point, the main.js file:

      Then add the following highlighted import line:

      vuex-shopping-cart/src/main.js

      import { createApp } from 'vue'
      import App from './App.vue'
      import router from './router'
      import store from './store'
      import './../node_modules/bulma/css/bulma.css'
      
      createApp(App).use(store).use(router).mount('#app')
      

      Save and close the file.

      In this app, you’ll use the Axios module to make requests to your server. Add the Axios module by running the following command:

      Now, run the app to make sure it is working:

      Navigate to http://localhost:8080 in your browser of choice. You will find the Vue app welcome page:

      Default Vue page when running your app in development mode

      Once you have confirmed that Vue is working, stop your server with CTRL+C.

      In this step, you globally installed Vue CLI in your computer, created a Vue project, installed the required npm packages Axios and Bulma, and imported Bulma to the project in the main.js file. Next, you will set up a back-end API to store data for your app.

      Step 2 — Setting Up the Backend

      In this step, you will create a separate backend to work with your Vue project. This will be in a different project folder from your front-end Vue application.

      First, move out of your Vue directory:

      Make a separate directory named cart-backend:

      Once you have your back-end folder, make it your working directory:

      You will get started by initializing the project with the necessary file. Create the file structure of your app with the following commands:

      • touch server.js
      • touch server-cart-data.json
      • touch server-product-data.json

      You use the touch command here to create empty files. The server.js file will hold your Node.js server, and the JSON will hold data for the shop’s products and the user’s shopping cart.

      Now run the following command to create a package.json file:

      For more information on npm and Node, check out our How To Code in Node.js series.

      Install these back-end dependencies into your Node project:

      • npm install concurrently express body-parser

      Express is a Node framework for web applications, which will provide useful abstractions for handling API requests. Concurrently will be used to run the Express back-end server and the Vue.js development server simulteneously. Finally, body-parser is an Express middleware that will parse requests to your API.

      Next, open a server.js file in the root of your application:

      Then add the following code:

      cart-backend/server.js

      const express = require('express');
      const bodyParser = require('body-parser');
      const fs = require('fs');
      const path = require('path');
      
      const app = express();
      const PRODUCT_DATA_FILE = path.join(__dirname, 'server-product-data.json');
      const CART_DATA_FILE = path.join(__dirname, 'server-cart-data.json');
      
      app.set('port', (process.env.PORT || 3000));
      app.use(bodyParser.json());
      app.use(bodyParser.urlencoded({ extended: true }));
      app.use((req, res, next) => {
        res.setHeader('Cache-Control', 'no-cache, no-store, must-revalidate');
        res.setHeader('Pragma', 'no-cache');
        res.setHeader('Expires', '0');
        next();
      });
      
      app.listen(app.get('port'), () => {
        console.log(`Find the server at: http://localhost:${app.get('port')}/`);
      });
      

      This snippet first adds the Node modules to your backend, including the fs module to write to your filesystem and the path module to make defining filepaths easier. You then initialize the Express app and save references to your JSON files as PRODUCT_DATA_FILE and CART_DATA_FILE. These will be used as data repositories. Finally, you created an Express server, set the port, created a middleware to set the response headers, and set the server to listen on your port. For more information on Express, see the official Express documentation.

      The setHeader method sets the header of the HTTP responses. In this case, you are using Cache-Control to direct the caching of your app. For more information on this, check out the Mozilla Developer Network article on Cache-Control.

      Next, you will create an API endpoint that your frontend will query to add an item to the shopping cart. To do this, you will use app.post to listen for an HTTP POST request.

      Add the following code to server.js just after the last app.use() middleware:

      cart-backend/server.js

      ...
      app.use((req, res, next) => {
        res.setHeader('Cache-Control', 'no-cache, no-store, must-revalidate');
        res.setHeader('Pragma', 'no-cache');
        res.setHeader('Expires', '0');
        next();
      });
      
      app.post('/cart', (req, res) => {
          fs.readFile(CART_DATA_FILE, (err, data) => {
            const cartProducts = JSON.parse(data);
            const newCartProduct = { 
              id: req.body.id,
              title: req.body.title,
              description: req.body.description,
              price: req.body.price,
              image_tag: req.body.image_tag, 
              quantity: 1 
            };
            let cartProductExists = false;
            cartProducts.map((cartProduct) => {
              if (cartProduct.id === newCartProduct.id) {
                cartProduct.quantity++;
                cartProductExists = true;
              }
            });
            if (!cartProductExists) cartProducts.push(newCartProduct);
            fs.writeFile(CART_DATA_FILE, JSON.stringify(cartProducts, null, 4), () => {
              res.setHeader('Cache-Control', 'no-cache');
              res.json(cartProducts);
            });
          });
        });
      
      app.listen(app.get('port'), () => {
        console.log(`Find the server at: http://localhost:${app.get('port')}/`);
      });
      

      This code receives the request object containing the cart items from the frontend and stores them in the server-cart-data.json file in the root of your project. Products here are JavaScript objects with id, title, description, price, image_tag, and quantity properties. The code also checks if the cart already exists to ensure that requests for a repeated product only increase the quantity.

      Now, add code to create an API endpoint to remove an item from the shopping cart. This time, you will use app.delete to listen for an HTTP DELETE request.

      Add the following code to server.js just after the previous endpoint:

      cart-backend/server.js

      ...
            fs.writeFile(CART_DATA_FILE, JSON.stringify(cartProducts, null, 4), () => {
              res.setHeader('Cache-Control', 'no-cache');
              res.json(cartProducts);
            });
          });
        });
      
      app.delete('/cart/delete', (req, res) => {
        fs.readFile(CART_DATA_FILE, (err, data) => {
          let cartProducts = JSON.parse(data);
          cartProducts.map((cartProduct) => {
            if (cartProduct.id === req.body.id && cartProduct.quantity > 1) {
              cartProduct.quantity--;
            } else if (cartProduct.id === req.body.id && cartProduct.quantity === 1) {
              const cartIndexToRemove = cartProducts.findIndex(cartProduct => cartProduct.id === req.body.id);
              cartProducts.splice(cartIndexToRemove, 1);
            }
          });
          fs.writeFile(CART_DATA_FILE, JSON.stringify(cartProducts, null, 4), () => {
            res.setHeader('Cache-Control', 'no-cache');
            res.json(cartProducts);
          });
        });
      });
      
      app.listen(app.get('port'), () => {
        console.log(`Find the server at: http://localhost:${app.get('port')}/`); // eslint-disable-line no-console
      });
      

      This code receives the request object containing the item to be removed from the cart and checks the server-cart-data.json file for this item via its id. If it exists and the quantity is greater than one, then the quantity of the item in the cart is deducted. Otherwise, if the item’s quantity is less than 1, it will be removed from the cart and the remaining items will be stored in the server-cart-data.json file.

      To give your user additional functionality, you can now create an API endpoint to remove all items from the shopping cart. This will also listen for a DELETE request.

      Add the following highlighted code to server.js after the previous endpoint:

      cart-backend/server.js

      ...
          fs.writeFile(CART_DATA_FILE, JSON.stringify(cartProducts, null, 4), () => {
            res.setHeader('Cache-Control', 'no-cache');
            res.json(cartProducts);
          });
        });
      });
      
      app.delete('/cart/delete/all', (req, res) => {
        fs.readFile(CART_DATA_FILE, () => {
          let emptyCart = [];
          fs.writeFile(CART_DATA_FILE, JSON.stringify(emptyCart, null, 4), () => {
            res.json(emptyCart);
          });
        });
      });
      
      app.listen(app.get('port'), () => {
        console.log(`Find the server at: http://localhost:${app.get('port')}/`); // eslint-disable-line no-console
      });
      

      This code is responsible for removing all the items from the cart by returning an empty array.

      Next, you will create an API endpoint to retrieve all the products from the product storage. This will use app.get to listen for a GET request.

      Add the following code to server.js after the previous endpoint:

      cart-backend/server.js

      ...
      app.delete('/cart/delete/all', (req, res) => {
        fs.readFile(CART_DATA_FILE, () => {
          let emptyCart = [];
          fs.writeFile(CART_DATA_FILE, JSON.stringify(emptyCart, null, 4), () => {
            res.json(emptyCart);
          });
        });
      });
      
      app.get("https://www.digitalocean.com/products", (req, res) => {
        fs.readFile(PRODUCT_DATA_FILE, (err, data) => {
          res.setHeader('Cache-Control', 'no-cache');
          res.json(JSON.parse(data));
        });
      });
      ...
      

      This code uses the file system’s native readFile method to fetch all the data in the server-product-data.json file and returns them in JSON format.

      Finally, you will create an API endpoint to retrieve all the items from the cart storage:

      cart-backend/server.js

      ...
      app.get("https://www.digitalocean.com/products", (req, res) => {
        fs.readFile(PRODUCT_DATA_FILE, (err, data) => {
          res.setHeader('Cache-Control', 'no-cache');
          res.json(JSON.parse(data));
        });
      });
      
      app.get('/cart', (req, res) => {
        fs.readFile(CART_DATA_FILE, (err, data) => {
          res.setHeader('Cache-Control', 'no-cache');
          res.json(JSON.parse(data));
        });
      });
      ...
      

      Similarly, this code uses the file system’s native readFile method to fetch all the data in the server-cart-data.json file and returns them in JSON format.

      Save and close the server.js file.

      Next, you will add some mock data to your JSON files for testing purposes.

      Open up the server-cart-data.json file you created earlier:

      • nano server-cart-data.json

      Add the following array of product objects:

      cart-backend/server-cart-data.json

      [
          {
              "id": 2,
              "title": "MIKANO Engine",
              "description": "Lorem ipsum dolor sit amet, consectetur  dignissimos suscipit voluptatibus distinctio, error nostrum expedita omnis ipsum sit inventore aliquam sunt quam quis! ",
              "price": 650.9,
              "image_tag": "diesel-engine.png",
              "quantity": 1
          },
          {
              "id": 3,
              "title": "SEFANG Engine",
              "description": "Lorem ipsum dolor sit amet, consectetur  dignissimos suscipit voluptatibus distinctio, error nostrum expedita omnis ipsum sit inventore aliquam sunt quam quis!",
              "price": 619.9,
              "image_tag": "sefang-engine.png",
              "quantity": 1
          }
      ]
      

      This shows two engines that will start out in the user’s shopping cart.

      Save and close the file.

      Now open the server-product-data.json file:

      • nano server-product-data.json

      Add the following data in server-product-data.json file:

      cart-backend/server-product-data.json

      [
          {
            "id": 1,
            "title": "CAT Engine",
            "description": "Lorem ipsum dolor sit amet, consectetur  dignissimos suscipit voluptatibus distinctio, error nostrum expedita omnis ipsum sit inventore aliquam sunt quam quis!",
            "product_type": "power set/diesel engine",
            "image_tag": "CAT-engine.png",
            "created_at": 2020,
            "owner": "Colton",
            "owner_photo": "image-colton.jpg",
            "email": "colt@gmail.com",
            "price": 719.9
          },
          {
            "id": 2,
            "title": "MIKANO Engine",
            "description": "Lorem ipsum dolor sit amet, consectetur  dignissimos suscipit voluptatibus distinctio, error nostrum expedita omnis ipsum sit inventore aliquam sunt quam quis! ",
            "product_type": "power set/diesel engine",
            "image_tag": "diesel-engine.png",
            "created_at": 2020,
            "owner": "Colton",
            "owner_photo": "image-colton.jpg",
            "email": "colt@gmail.com",
            "price": 650.9
          },
          {
            "id": 3,
            "title": "SEFANG Engine",
            "description": "Lorem ipsum dolor sit amet, consectetur  dignissimos suscipit voluptatibus distinctio, error nostrum expedita omnis ipsum sit inventore aliquam sunt quam quis!",
            "product_type": "power set/diesel engine",
            "image_tag": "sefang-engine.png",
            "created_at": 2017,
            "owner": "Anne",
            "owner_photo": "image-anne.jpg",
            "email": "anne@gmail.com",
            "price": 619.9
          },
          {
            "id": 4,
            "title": "CAT Engine",
            "description": "Lorem ipsum dolor sit amet, consectetur  dignissimos suscipit voluptatibus distinctio, error nostrum expedita omnis ipsum sit inventore aliquam sunt quam quis!",
            "product_type": "power set/diesel engine",
            "image_tag": "lawn-mower.png",
            "created_at": 2017,
            "owner": "Irene",
            "owner_photo": "image-irene.jpg",
            "email": "irene@gmail.com",
            "price": 319.9
          }
      
        ]
      

      This will hold all the possible products that the user can put in their cart.

      Save and close the file.

      Finally, execute this command to run the server:

      You will receive something like this on your terminal:

      Output

      Find the server at: http://localhost:3000/

      Leave this server running in this window.

      Finally, you will set up a proxy server in your Vue app. This will enable the connection between the frontend and backend.

      Go to the root directory of your Vue app:

      In the terminal, run this command to create a Vue configuration file:

      Then, add this code:

      vuex-shopping-cart/vue.config.js

      module.exports = {
        devServer: {
          proxy: {
            '/api': {
              target: 'http://localhost:3000/',
              changeOrigin: true,
              pathRewrite: {
                '^/api': ''
              }
            }
          }
        }
      }
      

      This will send requests from your frontend to your back-end server at http://localhost:3000/. For more information on proxy configuration, review the Vue devServer.proxy documentation.

      Save and close the file.

      In this step, you wrote server-side code that will handle API endpoints for your shopping cart. You started by creating the file structure and ended with adding necessary code in the server.js file and data in your JSON files. Next, you will set up the state storage for your frontend.

      Step 3 — Setting Up State Management with Vuex

      In Vuex, the store is where the state of the application is kept. The application state can only be updated by dispatching actions within a component that will then trigger mutations in the store. The Vuex store is made up of the state, mutations, actions, and getters.

      In this step, you’re going to build each of these pieces, after which you will couple everything together into a Vuex store.

      State

      Now you will create a place to store state for your application.

      The store folder in the root directory src of your project is automatically created at the time of the project setup. Locate the store folder in the src directory of your project then create a new folder named modules:

      Inside this folder, create the product and cart folders:

      • mkdir src/store/modules/product
      • mkdir src/store/modules/cart

      These will hold all the state files for your product inventory and your user’s cart. You will build these two files up at the same time, each open in a separate terminal. This way, you will be able to compare your mutations, getters, and actions side-by-side.

      Finally, open an index.js file in the product folder:

      • nano src/store/modules/product/index.js

      Add the following code to create a state object containing your productItems:

      vuex-shopping-cart/src/store/modules/product/index.js

      import axios from 'axios';
      const state = {
        productItems: [] 
      }
      

      Save the file and keep it open.

      Similarly, in a new terminal, add an index.js file to the cart directory with the following:

      • nano src/store/modules/cart/index.js

      Then add code for the cartItems:

      vuex-shopping-cart/src/store/modules/cart/index.js

      import axios from 'axios';
      const state = {
        cartItems: []
      }
      

      Save this file, but keep it open.

      In these code snippets, you imported the Axios module and set the state. The state is a store object that holds the application-level data that needs to be shared between components.

      Now that you’ve set the states, head over to mutations.

      Mutations

      Mutations are methods that modify the store state. They usually consist of a string type and a handler that accepts the state and payload as parameters.

      You will now create all the mutations for your application.

      Add the following code in the product/index.js file just after the state section:

      vuex-shopping-cart/src/store/modules/product/index.js

      ...
      const mutations = {
        UPDATE_PRODUCT_ITEMS (state, payload) {
          state.productItems = payload;
        }
      }
      

      This creates a mutations object that holds an UPDATE_PRODUCT_ITEMS method that sets the productItems array to the payload value.

      Similarly, add the following code in the cart/index.js file just after the state section:

      vuex-shopping-cart/src/store/modules/cart/index.js

      ...
      const mutations = {
        UPDATE_CART_ITEMS (state, payload) {
          state.cartItems = payload;
        }
      }
      

      This creates a similar UPDATE_CART_ITEMS for your user’s shopping cart. Note that this follows the Flux architecture style of making references to mutations in capital letters.

      Actions

      Actions are methods that will handle mutations, so that mutations are insulated from the rest of your application code.

      In product/index.js, create an actions object with all the actions for your application:

      vuex-shopping-cart/src/store/modules/product/index.js

      ...
      const actions = {
        getProductItems ({ commit }) {
          axios.get(`/api/products`).then((response) => {
            commit('UPDATE_PRODUCT_ITEMS', response.data)
          });
        }
      }
      

      Here the getProductItems method sends an asynchronous GET request to the server using the Axios package that you installed earlier. When the request is successful, the UPDATE_PRODUCT_ITEMS mutation is called with the response data as the payload.

      Next, add the following actions object to cart/index.js:

      vuex-shopping-cart/src/store/modules/cart/index.js

      ...
      const actions = {
        getCartItems ({ commit }) {
          axios.get('/api/cart').then((response) => {
            commit('UPDATE_CART_ITEMS', response.data)
          });
        },
        addCartItem ({ commit }, cartItem) {
          axios.post('/api/cart', cartItem).then((response) => {
            commit('UPDATE_CART_ITEMS', response.data)
          });
        },
        removeCartItem ({ commit }, cartItem) {
          axios.delete('/api/cart/delete', cartItem).then((response) => {
            commit('UPDATE_CART_ITEMS', response.data)
          });
        },
        removeAllCartItems ({ commit }) {
          axios.delete('/api/cart/delete/all').then((response) => {
            commit('UPDATE_CART_ITEMS', response.data)
          });
        }
      }
      
      

      In this file, you create the getCartItems method, which sends an asynchronous GET request to the server. When the request is successful, the UPDATE_CART_ITEMS mutation is called with the response data as the payload. The same happens with the removeAllCartItems method, although it makes a DELETE request to the server. The removeCartItem and addCartItem methods receives the cartItem object as a parameter for making a DELETE or POST request. After a successful request, the UPDATE_CART_ITEMS mutation is called with the response data as the payload.

      You used ES6 destructuring to decouple the commit method from the Vuex context object. This is similar to using context.commit.

      Getters

      Getters are to an application store what computed properties are to a component. They return computed information from store state methods that involve receiving computed state data.

      Next, create a getters object to get all the information for the product module:

      vuex-shopping-cart/src/store/modules/product/index.js

      ...
      const getters = {
        productItems: state => state.productItems,
        productItemById: (state) => (id) => {
          return state.productItems.find(productItem => productItem.id === id)
        }
      }
      

      Here, you made a method productItems that returns the list of product items in the state, followed by productItemById, a higher order function that returns a single product by its id.

      Next, create a getters object in cart/index.js:

      vuex-shopping-cart/src/store/modules/cart/index.js

      ...
      const getters = {
        cartItems: state => state.cartItems,
        cartTotal: state => {
          return state.cartItems.reduce((acc, cartItem) => {
            return (cartItem.quantity * cartItem.price) + acc;
          }, 0).toFixed(2);
        },
        cartQuantity: state => {
          return state.cartItems.reduce((acc, cartItem) => {
            return cartItem.quantity + acc;
          }, 0);
        }
      }
      

      In this snippet, you made the cartItems method, which returns the list of cart items in the state, followed by cartTotal, which returns the computed value of the total amount of cart items available for checkout. Finally, you made the cartQuantity method, which retuns the quantity of items in the cart.

      Exporting the Module

      The final part of the product and cart modules will export the state, mutations, actions, and getters objects so that other parts of the application can access them.

      In product/index.js, add the following code at the end of the file:

      vuex-shopping-cart/src/store/modules/product/index.js

      ...
      const productModule = {
        state,
        mutations,
        actions,
        getters
      }
      
      export default productModule;
      

      This collects all your state objects into the productModule object, then exports it as a module.

      Save product/index.js and close the file.

      Next, add similar code to cart/index.js:

      vuex-shopping-cart/src/store/modules/product/index.js

      ...
          const cartModule = {
        state,
        mutations,
        actions,
        getters
      }
      export default cartModule;
      

      This exports the module as cartModule.

      Setting up the Store

      With the state, mutations, actions, and getters all set up, the final part of integrating Vuex into your application is creating the store. Here you will harness the Vuex modules to split your application store into two manageable fragments.

      To create your store, open up the index.js file in your store folder:

      Add the following highlighted lines:

      vuex-shopping-cart/src/store/index.js

      import { createStore } from 'vuex'
      import product from'./modules/product';
      import cart from './modules/cart';
      
      export default createStore({
        modules: {
          product,
          cart
        }
      })
      

      Save the file, then exit the text editor.

      You have now created the methods needed for state management and have created the store for your shopping cart. Next you will create user interface (UI) components to consume the data.

      Step 4 — Creating Interface Components

      Now that you have the store for your shopping cart set up, you can move onto making the components for the user interface (UI). This will include making some changes to the router and making front-end components for your navigation bar and list and item views of your products and your cart.

      First, you will update your vue-router setup. Remember that when you used the Vue CLI tool to scaffold your application, you chose the router option, which allowed Vue to automatically set up the router for you. Now you can re-configure the router to provide paths for Cart_List.vue and Product_List.vue, which are Vue components you will make later.

      Open up the router file with the following command:

      • nano vuex-shopping-cart/src/router/index.js

      Add the following highlighted lines:

      vuex-shopping-cart/src/router/index.js

      import { createRouter, createWebHashHistory } from 'vue-router'
      import CartList from '../components/cart/Cart_List.vue';
      import ProductList from '../components/product/Product_List.vue';
      
      const routes = [
        {
          path: '/inventory',
          component: ProductList
        },
        {
          path: '/cart',
          component: CartList
        },
        {
          path: '/',
          redirect: '/inventory'
        },
      ]
      const router = createRouter({
        history: createWebHashHistory(),
        routes
      })
      
      export default router
      

      This creates the /inventory route for your products and the /cart route for the items in your cart. It also redirects your root path / to the product view.

      Once you have added this code, save and close the file.

      Now you can set up your UI component directories. Run this command on your terminal to move to the component’s directory:

      Run this command to create three new sub-folders under the component’s directory:

      core will hold essential parts of your application, such as the navigation bar. cart and product will hold the item and list views of the shopping cart and the total inventory.

      Under the core directory, create the Navbar.vue file by running this command:

      Under the cart directory, create the files Cart_List_Item.vue and Cart_List.vue:

      • touch cart/Cart_List_Item.vue cart/Cart_List.vue

      Finally, under the product directory, create these two files:

      • touch product/Product_List_Item.vue product/Product_List.vue

      Now that the file structure has been outlined, you can move on to creating the individual components of your front-end app.

      In the navbar, the cart navigation link will display the quantity of items in your cart. You will use the Vuex mapGetters helper method to directly map store getters with component computed properties, allowing your app to get this data from the store’s getters to the Navbar component.

      Open the navbar file:

      Replace the code with the following:

      vuex-shopping-cart/src/components/core/Navbar.vue

      <template>
          <nav class="navbar" role="navigation" aria-label="main navigation">
            <div class="navbar-brand">
              <a
                role="button"
                class="navbar-burger burger"
                aria-label="menu"
                aria-expanded="false"
                data-target="navbarBasicExample"
              >
                <span aria-hidden="true"></span>
                <span aria-hidden="true"></span>
                <span aria-hidden="true"></span>
              </a>
            </div>
            <div id="navbarBasicExample" class="navbar-menu">
              <div class="navbar-end">
                <div class="navbar-item">
                  <div class="buttons">
                    <router-link to="/inventory" class="button is-primary">
                     <strong> Inventory</strong>
                    </router-link>
                    <router-link to="/cart"  class="button is-warning">   <p>
          Total cart items:
          <span> {{cartQuantity}}</span> </p>
                    </router-link>
                  </div>
                </div>
              </div>
            </div>
          </nav>
      </template>
      <script>
      import {mapGetters} from "vuex"
      export default {
          name: "Navbar",
          computed: {
          ...mapGetters([
            'cartQuantity'
          ])
        },
        created() {
          this.$store.dispatch("getCartItems");
        }
      }
      </script>
      

      As a Vue component, this file starts out with a template element, which holds the HTML for the component. This snippet includes multiple navbar classes that use pre-made styles from the Bulma CSS framework. For more information, check out the Bulma documentation.

      This also uses the router-link elements to connect the app to your products and cart, and uses cartQuantity as a computed property to dynamically keep track of the number of items in your cart.

      The JavaScript is held in the script element, which also handles state management and exports the component. The getCartItems action gets dispatched when the navbar component is created, updating the store state with all the cart items from the response data received from the server. After this, the store getters recompute their return values and the cartQuantity gets rendered in the template. Without dispatching the getCartItems action on the created life cycle hook, the value of cartQuantity will be 0 until the store state is modified.

      Save and close the file.

      Product_List Component

      This component is the parent to the Product_List_Item component. It will be responsible for passing down the product items as props to the Product_List_Item (child) component.

      First, open up the file:

      • nano product/Product_List.vue

      Update Product_List.vue as follows:

      vuex-shopping-cart/src/components/product/Product_List.vue

      <template>
        <div class="container is-fluid">
          <div class="tile is-ancestor">
            <div class="tile is-parent" v-for="productItem in productItems" :key="productItem.id">
            <ProductListItem :productItem="productItem"/>
            </div>
          </div>
        </div>
      </template>
      <script>
      import { mapGetters } from 'vuex';
      import Product_List_Item from './Product_List_Item'
      export default {
        name: "ProductList",
        components: {
          ProductListItem:Product_List_Item
        },
        computed: {
          ...mapGetters([
            'productItems'
          ])
        },
        created() {
          this.$store.dispatch('getProductItems');
        }
      };
      </script>
      

      Similar to the Navbar component logic discussed earlier, here the Vuex mapGetters helper method directly maps store getters with component computed properties to get the productItems data from the store. The getProductItems action gets dispatched when the ProductList component is created, updating the store state with all the product items from the response data received from the server. After this, the store getters re-computes their return values and the productItems gets rendered in the template. Without dispatching the getProductItems action on the created life cycle hook, there will be no product item displayed in the template until the store state is modified.

      Product_List_Item Component

      This component will be the direct child component to the Product_List component. It will receive the productItem data as props from its parent and render them in the template.

      Open Product_List_Item.vue:

      • nano product/Product_List_Item.vue

      Then add the following code:

      vuex-shopping-cart/src/components/product/Product_List_Item.vue

      <template>
          <div class="card">
            <div class="card-content">
              <div class="content">
                <h4>{{ productItem.title }}</h4>
                <a
                  class="button is-rounded is-pulled-left"
                  @click="addCartItem(productItem)"
                >
                  <strong>Add to Cart</strong>
                </a>
                <br />
                <p class="mt-4">
                  {{ productItem.description }}
                </p>
              </div>
              <div class="media">
                <div class="media-content">
                  <p class="title is-6">{{ productItem.owner }}</p>
                  <p class="subtitle is-7">{{ productItem.email }}</p>
                </div>
                <div class="media-right">
                  <a class="button is-primary is-light">
                    <strong>$ {{ productItem.price }}</strong>
                  </a>
                </div>
              </div>
            </div>
          </div>
      </template>
      <script>
      import {mapActions} from 'vuex'
      export default {
        name: "ProductListItem",
        props: ["productItem"],
        methods: {
          ...mapActions(["addCartItem"]),
        },
      };
      </script>
      

      In addition to the mapGetters helper function used in the previous components, Vuex also provides you with the mapActions helper function to directly map the component method to the store’s actions. In this case, you use the mapAction helper function to map the component method to the addCartItem action in the store. Now you can add items to the cart.

      Save and close the file.

      Cart_List Component

      This component is responsible for displaying all the product items added to the cart and also the removal of all the items from the cart.

      To create this component, first open the file:

      Next, update Cart_List.vue as follows:

      vuex-shopping-cart/src/components/cart/Cart_List.vue

      <template>
        <div id="cart">
          <div class="cart--header has-text-centered">
            <i class="fa fa-2x fa-shopping-cart"></i>
          </div>
          <p v-if="!cartItems.length" class="cart-empty-text has-text-centered">
            Add some items to the cart!
          </p>
          <ul>
            <li class="cart-item" v-for="cartItem in cartItems" :key="cartItem.id">
                <CartListItem :cartItem="cartItem"/>
            </li>
            <div class="notification is-success">
              <button class="delete"></button>
              <p>
                Total Quantity:
                <span class="has-text-weight-bold">{{ cartQuantity }}</span>
              </p>
            </div>
            <br>
          </ul>
          <div class="buttons">
          <button :disabled="!cartItems.length" class="button is-info">
            Checkout (<span class="has-text-weight-bold">${{ cartTotal }}</span>)
          </button>
      
       <button class="button is-danger is-outlined" @click="removeAllCartItems">
          <span>Delete All items</span>
          <span class="icon is-small">
            <i class="fas fa-times"></i>
          </span>
        </button>
             </div>
        </div>
      </template>
      <script>
      import { mapGetters, mapActions } from "vuex";
      import CartListItem from "./Cart_List_Item";
      export default {
        name: "CartList",
        components: {
          CartListItem
        },
        computed: {
          ...mapGetters(["cartItems", "cartTotal", "cartQuantity"]),
        },
        created() {
          this.$store.dispatch("getCartItems");
        },
        methods: {
          ...mapActions(["removeAllCartItems"]),
        }
      };
      </script>
      

      This code uses a v-if statement in the template to conditionally render a message if the cart is empty. Otherwise, it iterates through the store of cart items and renders them to the page. You also loaded in the cartItems, cartTotal, and cartQuantity getters to compute the data properties, and brought in the removeAllCartItems action.

      Save and close the file.

      Cart_List_Item Component

      This component is the direct child component of the Cart_List component. It receives the cartItem data as props from its parent and renders them in the template. It is also responsible for incrementing and decrementing the quantity of items in the cart.

      Open up the file:

      • nano cart/Cart_List_Item.vue

      Update Cart_List_Item.vue as follows:

      vuex-shopping-cart/src/components/cart/Cart_List_Item.vue

      <template>
        <div class="box">
          <div class="cart-item__details">
            <p class="is-inline">{{cartItem.title}}</p>
            <div>
              <span class="cart-item--price has-text-info has-text-weight-bold">
                ${{cartItem.price}} X {{cartItem.quantity}}
              </span>
      
              <span>
                <i class="fa fa-arrow-circle-up cart-item__modify" @click="addCartItem(cartItem)"></i>
                <i class="fa fa-arrow-circle-down cart-item__modify" @click="removeCartItem(cartItem)"></i>
              </span>
            </div>
      
          </div>
        </div>
      </template>
      <script>
      import { mapActions } from 'vuex';
      export default {
        name: 'CartListItem',
        props: ['cartItem'],
        methods: {
          ...mapActions([
            'addCartItem',
            'removeCartItem'
          ])
        }
      }
      </script>
      

      Here, you are using the mapAction helper function to map the component method to the addCartItem and removeCartItem actions in the store.

      Save and close the file.

      Lastly, you will update the App.vue file to bring these components into your app. First, move back to the root folder of your project:

      Now open the file:

      Replace the contents with the following code:

      vuex-shopping-cart/src/App.vue

      <template>
        <div>
          <Navbar/>
          <div class="container mt-6">
            <div class="columns">
              <div class="column is-12 column--align-center">
                <router-view></router-view>
              </div>
            </div>
          </div>
        </div>
      </template>
      <script>
      import Navbar from './components/core/Navbar'
      export default {
        name: 'App',
        components: {
          Navbar
        }
      }
      </script>
      <style>
      html,
      body {
        height: 100%;
        background: #f2f6fa;
      }
      </style>
      

      App.vue is the root of your application defined in Vue component file format. Once you have made the changes, save and close the file.

      In this step, you set up the frontend of your shopping cart app by creating components for the navigation bar, the product inventory, and the shopping cart. You also used the store actions and getters that you created in a previous step. Next, you will get your application up and running.

      Step 5 — Running the Application

      Now that your app is ready, you can start the development server and try out the final product.

      Run the following command in the root of your front-end project:

      This will start a development server that allows you to view your app on http://localhost:8080. Also, make sure that your backend is running in a separate terminal; you can do this by running the following command in your cart-backend project:

      Once your backend and your frontend are running, navigate to http://localhost:8080 in your browser. You will find your functioning shopping cart application:

      Animation of user adding and deleting products from the shopping cart application

      Conclusion

      In this tutorial, you built an online shopping cart app using Vue.js and Vuex for data management. These techniques can be reused to form the basis of an e-commerce shopping application. If you would like to learn more about Vue.js, check out our Vue.js topic page.



      Source link

      How To Generate a Vue.js Single Page App With the Vue CLI


      The author selected Open Sourcing Mental Illness to receive a donation as part of the Write for DOnations program.

      Introduction

      Vue.js is a popular JavaScript framework for creating user interfaces. Created in 2014 by Evan You (formally of Google), Vue.js is often described as a combination of React and Angular, borrowing the prop-driven development of React and the templating power of Angular. This makes Vue an accessible framework for beginners to pick up, especially since it focuses on traditional HTML and CSS, rather than being a CSS-in-JS framework like React or relying on TypeScript (a superset of JavaScript) like Angular does.

      When starting a new project, it’s best to familiarize yourself with the technology’s tools and features. One important tool for Vue.js development is its command line interface (CLI) known as Vue CLI 3. The Vue CLI offers a number of useful features that enhance the Vue development experience, but the main feature is its ability to generate and pre-configure a new single-page application with the vue create command.

      By the end of this tutorial, you will have a working Vue.js application running on a local Node server. This local server uses hot module reloading via Webpack to provide immediate feedback, rendered in-browser as you work. Along the way, you will create .vue single-file components (SFC), such as a header and a footer. All of this you can save as a solid foundation for any future Vue projects.

      Prerequisites

      To follow this tutorial, you will need the following:

      Step 1 — Downloading Vue CLI 3

      To download Vue CLI 3, you will need to run a command either via npm or Yarn, whichever you prefer. npm or Node Package Manager is a way to download and manage other people’s code to use in your project as a dependency. Yarn, on the other hand, executes NPM commands under the hood but provides additional features like caching. It’s up to personal preference regarding which one to use. However, it is important to note that it’s not recommended to mix commands. It’s best to be consistent with one or the other for the duration of your project.

      Moving forward, this tutorial will use npm commands. The following command will download the necessary Vue CLI files from the registrar, which in this case is the npm (Node Package Manager) service:

      npm i -g @vue/cli
      

      Note: On some systems, installing an npm package globally can result in a permission error, which will interrupt the installation. Since it is a security best practice to avoid using sudo with npm install, you can instead resolve this by changing npm’s default directory. If you encounter an EACCES error, follow the instructions at the official npm documentation.

      You install this globally in order to use the CLI anywhere on your machine. If you don’t install this globally, it will only work in the directory that you installed it at. In the case of the command options, i means “install” and -g is a flag to install the code globally on your computer.

      To verify if Vue CLI 3 was properly installed, run the following:

      vue --version
      

      You will receive the following output with a version number. Your version number may differ, but if you receive a response with a version number, you’ve properly installed Vue CLI 3:

      Output

      @vue/cli 4.5.6

      To update Vue CLI 3, run the previous commands in this section, and the latest version will be installed.

      At this point, you have successfully downloaded npm globally along with the Vue CLI tool that you will use in the next section to create a generated Vue.js project.

      Step 2 — Generating a Single-Page Application

      As you develop Vue.js applications, you may find that manually configuring a project is not the most productive use of your time, since configuring a new Vue.js project from scratch can take hours. This is the true power of Vue CLI: It provides you with a pre-generated template that is based on your specifications. Because of this, it’s already configured so you can start developing your website or application right away. Vue CLI 3 will ask you a few questions via a command line prompt about your project, download the required files, and pre-configure it for you so you are ready to work as soon as it’s done.

      To generate a single-page application, navigate to the directory you’d like your Vue project in, then run the following:

      vue create vue-starter-project
      

      The highlighted section of the command is the name of the root directory of the project. This will be the name of the folder that contains all of your Vue.js project files. This can be whatever you’d like, but in the case of this tutorial, you will use vue-starter-project.

      Once you type out that command, continue by pressing Enter. You will then receive the following prompt:

      Vue CLI v4.5.6
      ? Please pick a preset: 
        Default ([Vue 2] babel, eslint) 
        Default (Vue 3 Preview) ([Vue 3] babel, eslint) 
      ❯ Manually select features 
      

      If you do not want to configure your project and opt for the defaults, you can do so with either Vue 2 or Vue 3. For the purpose of this tutorial though, it’s recommended to manually select your features. By selecting specific features, you will see how each option you selected was installed by the CLI.

      Select Manually select features with ENTER. Immediately you’ll receive a number of different options, including: Choose Vue version, TypeScript, Router, and Vuex. Notice that some of these items are already selected (the bubble is filled in). You may select as many or as few as you’d like. However, for this tutorial, select the following by pressing <space> on the entry:

      ...
       ◉ Choose Vue version
       ◉ Babel
       ◉ TypeScript
       ◯ Progressive Web App (PWA) Support
       ◉ Router
       ◉ Vuex
       ◉ CSS Pre-processors
       ◉ Linter / Formatter
      ❯◯ Unit Testing
       ◯ E2E Testing
      

      Once you have your options selected, press the ENTER key. The CLI will ask you further questions regarding each of the features you selected for your project, in order. The first question will ask which version of Vue you’d like to use: 2.x or 3.x. You’ll use Vue 3 for this tutorial, but you may want to use Vue 2 if you want greater support from the Vue Community:

      ...
      ? Choose a version of Vue.js that you want to start the project with 
        2.x 
      ❯ 3.x (Preview)
      

      The next question is regarding TypeScript integration. If you are not familiar with TypeScript, that’s alright. This option was intentionally selected to illustrate how Vue CLI 3 downloads what you defined as required for unique project. This tutorial will not use the class-style syntax, but will use Babel alongside TypeScript.

      When encountering the following, enter N:

      ...
      Use class-style component syntax? (y/N) N
      

      In the following prompt, enter Y:

      ...
      ? Use Babel alongside TypeScript (required for modern mode, auto-detected polyfills, transpiling JSX)? (Y/n) Y
      

      Next, Vue CLI will ask about history mode. History mode will make each route its own URL. This means you will not have the /#/ (hash) in your application’s URL. If you do use history mode, you will need a Node server to run your project. This is not a problem, because Vue CLI 3 provides you with a Node server.

      Type Y to answer yes to history mode:

      ...
      ? Use history mode for router? (Requires proper server setup for index fallback in production) (Y/n) Y
      

      The next question is regarding CSS pre-processors such as Sass or LESS. A CSS pre-processor is CSS with added features like nesting and variables. The browser cannot read this, so when the project is built, Node will compile all of your SCSS or LESS code to traditional CSS. Since you are using Node to build your project, it’s recommended to select Sass/SCSS (with node-sass) as your pre-processor. Later on, you’ll add lang attributes in your .vue components to enable SCSS on a per component basis:

      ...
      ? Pick a CSS pre-processor (PostCSS, Autoprefixer and CSS Modules are supported by default): 
        Sass/SCSS (with dart-sass) 
      ❯ Sass/SCSS (with node-sass) 
        Less 
        Stylus 
      

      After that, you will receive some questions regarding the linter style. A linter is a program that evaluates your code as you develop your application. This linter can enforce a number of syntactical rules during development. In addition to this, your integrated development environment (IDE) can read this configuration file and format your code on save. This will keep your code consistent no matter who works on your project and what operating system or IDE a developer is using.

      For this tutorial, choose ESLint + Standard config:

      ...
      ? Pick a linter / formatter config: 
        ESLint with error prevention only 
        ESLint + Airbnb config 
      ❯ ESLint + Standard config 
        ESLint + Prettier 
        TSLint (deprecated) 
      

      This selects a set of rules for ESLint to enforce. These configurations include options like the use of trailing commas, semi-colons at the end of a line, or using const over var in JavaScript.

      The next option is selecting when you want ESLint to format your code. This can be either on save or when you commit your code to a service like GitHub, GitLab, or BitBucket. It’s recommended to select Lint on save so you can review any changes before committing to version control:

      ...
      ? Pick additional lint features: (Press <space> to select, <a> to toggle all, <i> to invert selection)
      ❯◉ Lint on save
       ◯ Lint and fix on commit
      

      Once you select your lint features, Vue CLI will ask you about how you want to store these configurations, whether in dedicated files or in the package.json. It’s considered standard practive to store configurations in their own files for a few reasons. One, configurations are easier to share between projects this way, and two, you’ll be keeping your package.json as legible as possible by only defining the important information about your app:

      ...
      ? Where do you prefer placing config for Babel, ESLint, etc.? (Use arrow keys)
      ❯ In dedicated config files 
        In package.json
      

      Once you are done, the CLI tool will ask if you want to save this selection as a preset for future projects. This is useful if you are generating projects for your employer and you want everything to stay consistent.

      Go ahead and save this configuraion as a preset; Vue CLI will ask you to rename it. Name it DigitalOcean Vue Tutorial Series:

      ...
      ? Save this as a preset for future projects? Yes
      ? Save preset as: DigitalOcean Vue Tutorial Series
      

      Now you can use these exact same settings for a future project.

      At this point, you will have something along the lines of this in your terminal summarizing all of your options:

      ? Please pick a preset: Manually select features
      ? Check the features needed for your project: Choose Vue version, Babel, TS, Router, Vuex, CSS Pre-processors, Linter
      ? Choose a version of Vue.js that you want to start the project with 3.x (Preview)
      ? Use class-style component syntax? No
      ? Use Babel alongside TypeScript (required for modern mode, auto-detected polyfills, transpiling JSX)? Yes
      ? Use history mode for router? (Requires proper server setup for index fallback in production) Yes
      ? Pick a CSS pre-processor (PostCSS, Autoprefixer and CSS Modules are supported by default): Sass/SCSS (with node-sass)
      ? Pick a linter / formatter config: Standard
      ? Pick additional lint features: Lint on save
      ? Where do you prefer placing config for Babel, ESLint, etc.? In dedicated config files
      ? Save this as a preset for future projects? (y/N) 
      

      Press ENTER, and Vue CLI will start creating your app.

      When completed, cd (change directory) in your project name (vue-starter-project):

      Next, start the application with npm run serve. This will run your project at a port on your localhost, usually :8080. If it’s a different port, the CLI will tell you:

      npm run serve
      

      You do not need to download dependencies, as the CLI already did that for you. To view your generated project, open your browser of choice and visit localhost:8080 in the URL bar. You will find a welcome screen with the Vue logo and the technologies you’ve selected in the previous steps.

      Vue template screen

      You can leave this server running throughout this tutorial to monitor your changes.

      In this section, you selected a number of options specific to the project you are creating. Vue CLI downloaded all of the code needed and pre-configured it for you. You can now start working in the generated code base, including creating your own single-file .vue components.

      Now that you have a single-page application running on a Node server, make some changes to this by creating a standard header and footer. These AppHeader.vue and AppFooter.vue components will be imported in such a way that they’ll be present on each route.

      In a new terminal window, navigate into the root of your vue-starter-project folder and list out the files with the following command:

      You will receive the following output:

      Output

      README.md babel.config.js node_modules package-lock.json package.json public src tsconfig.json

      You can also view the contents of your project by opening your project in your editor of choice, such as Visual Studio Code. In either case, you will have access to a number of different files and directories. These config files in the root directory have been created because of the selections made during the intial generation of this project. The option In dedicated config files told Vue CLI to create config.js files for each service you are using, such as Babel, TypeScript, and ESLint. In addition to these files, there are a number of directories. This tutorial will go over these as you get to them.

      First, create a .vue file in the components directory and name it AppHeader.vue. You can do this right-clicking in the components directory and creating a new file in IDEs like VS Code. If you prefer terminal commands, you can do this in your computer’s terminal with the bash command touch:

      touch src/components/AppHeader.vue
      

      In this step, you are creating a single-file component that will contain all of the HTML, JavaScript, and SCSS that this chunk of code needs. Every .vue component contains three basic concerns or sections: <template>, <script>, and <style>. In this case, template is the component’s HTML.

      Open up the new file in your text editor.

      In this file, create a header by using the <header> tag inside of <template>. Inside of this <header>, add the Vue.js logo and a <p> element with the content My Vue.js Application:

      vue-starter-project/src/components/AppHeader.vue

      <template>
        <header>
          <img alt="Vue logo" src="https://www.digitalocean.com/community/tutorials/assets/logo.png" height="50">
          <p>My Vue.js Application</p>
        </header>
      </template>
      

      Keep your development server running throughout development. If you close or cancel the server process, you will not be able to view your application in the browser.

      Save the file.

      At this point, when you open your browser, you will not see the HTML rendered. That is because you need to import the newly created AppHeader.vue component into a component that is already mounted. Since App.vue is your main entry point, it’s best to import it there so our header appears on every route.

      Open up the App.vue file in your text editor, then delete the div with the ID of nav and add the following highlighted code:

      vue-starter-project/src/App.vue

      <template>
        <app-header />
        <router-view/>
      </template>
      
      <script>
      import AppHeader from '@/components/AppHeader.vue'
      
      export default {
        components: {
          AppHeader
        }
      }
      </script>
      

      When you import using ES6, you are essentially creating a variable to later reference in your code. In this case, you are storing the code from AppHeader.vue into a variable called AppHeader. You need to register it via the components property before you can use it.

      Once it’s imported, you deleted the #nav in the template and added <app-header /> before the <router-view />. This renders the component in the HTML.

      After completing this step, save any unsaved file and open your browser back to localhost:8080. Thanks to hot module reloading, you will now find your newly created header at the top of the page:

      Vue template with new header

      You’ve now created a single-file Vue component, used import to bring it into a mounted component, and monitored the change with hot module reloading (HMR). Moving forward, you will extend the functionality of components through the use of child components. You will also use SCSS (the pre-processor you selected earlier) on a per component basis with the lang attribute.

      Now that the header is imported properly into the application, return to AppHeader.vue in your text editor. Add navigation underneath <p>My Vue.js Application</p> by adding the following highlighted code:

      vue-starter-project/src/components/AppHeader.vue

      <template>
        <header>
          <img alt="Vue logo" src="https://www.digitalocean.com/community/tutorials/assets/logo.png" height="50">
          <p>My Vue.js Application</p>
          <nav>
            <ul>
              <li><router-link to="/">Home</router-link></li>
              <li><router-link to="/about">About</router-link></li>
            </ul>
          </nav>
        </header>
      </template>
      

      Now, style this to make it look more like a traditional navigation bar. Create a <style> tag at the end of the file.

      vue-starter-project/src/components/AppHeader.vue

      <template>
        <header>
          <img alt="Vue logo" src="https://www.digitalocean.com/community/tutorials/assets/logo.png" height="50">
          <p>My Vue.js Application</p>
          <nav>
            <ul>
              <li><router-link to="/">Home</router-link></li>
              <li><router-link to="/about">About</router-link></li>
            </ul>
          </nav>
        </header>
      </template>
      
      <style lang="scss">
      </style>
      

      During the inital setup, you selected the Sass/SCSS (with node-sass) option. This is why you added on the lang="scss" attribute to your style tag. If you are unfamiliar with SCSS, it’s recommended to view their official documentation for specifics on when to use nesting or variables.

      This lang attribute will give you the ability to write SCSS in your single-file component. Add the following highlighted contents in the style element:

      vue-starter-project/src/components/AppHeader.vue

      ...
      <style lang="scss">
        header {
          display: flex;
          border-bottom: 1px solid #ccc;
          padding: .5rem 1rem;
      
          p {
            margin-left: 1rem;
          }
        }
      
        nav {
          margin-left: auto;
      
          ul {
            list-style: none;
          }
      
          ul li {
            display: inline-flex;
            margin-left: 1rem;
          }
        }
      </style>
      

      This SCSS creates a horizontal navigation bar with declarations such as display: inline-flex (using Flexbox) and spaces each item out with margin-left auto. To separate the header from the rest of the content, some padding is applied with padding: .5rem 1rem along with a bottom border using border-bottom: 1px solid #ccc. You may notice that the p styles are inside of the header SCSS block. In traditional CSS, that is not allowed, but thanks for SCSS, you can do that. This is refered to as nesting. In this case, the p inside the header is the same as selecting header p in traditional CSS.

      Save your file and navigate to localhost:8080 in your browser to find the new style:

      New style for header in Vue template

      You now have created and styled your header component. Next, you will create the footer component.

      Now that you have a header, you will complete your example application with a footer. In the same components directory, create a new file with the name AppFooter.vue. The process of creating this component is the same as creating the AppHeader.vue. You can create the file in your editor or through the touch base command.

      touch src/components/AppFooter.vue
      

      As before, import this into your App.vue file. Open up App.vue and add the following highlighted code:

      vue-starter-project/src/App.vue

      <template>
        <app-header />
        <router-view/>
        <app-footer />
      </template>
      
      <script>
      import AppHeader from '@/components/AppHeader.vue'
      import AppFooter from '@/components/AppFooter.vue'
      
      export default {
        components: {
          AppHeader,
          AppFooter
        }
      }
      </script>
      ...
      

      This time, you’re importing the component after the router-view tag.

      Save the file, then open up AppFooter.vue. In your AppFooter.vue file, use the <footer> HTML tag with a paragraph:

      vue-starter-project/src/components/AppFooter.vue

      <template>
        <footer>
          <p>Copyright &copy; "current year" </p>
        </footer>
      </template>
      

      You now have a basic footer. Continue to expand on this to include the current year programmatically. This will be dynamic depending on what the year is. To achieve this, you will create a computed property. A computed property is a reactive value calculated with JavaScript.

      In Vue 3, you need to wrap your properties in the setup() function and return these values. Essentially, you are telling Vue to construct this component and provide the template to these reactive computed properties.

      To create a computed property, you’ll first need to deconstruct the computed function from the vue library. You will store this computed function and its value into a const. In Vue 3, you need to pass an anonymous function that returns a value:

      const year = computed(() => new Date().getFullYear())
      

      To add the setup function to your file, add the following script to the end of AppFooter.vue:

      vue-starter-project/src/components/AppFooter.vue

      ...
      <script>
      import { computed } from 'vue'
      
      export default {
        setup () {
          const year = computed(() => new Date().getFullYear())
        }
      }
      </script>
      

      After that, you will need to provide access to the computed property you created for the <template> to consume and render. Return an object with the year property and value in your setup() function:

      /vue-starter-project/src/components/AppFooter.vue

      ...
      setup () {
        const year = computed(() => new Date().getFullYear())
        return { year }
      }
      ...
      

      To use this value in the <template>, use interpolation with double curly braces. This is sometimes referred to the “moustache syntax”:

      /vue-starter-project/src/components/AppFooter.vue

      <template>
        <footer>
          <p>Copyright &copy; {{ year }}</p>
        </footer>
      </template>
      

      Save the file. You will now have the current year in your footer:

      Sample vue application with a computed header

      Conclusion

      In this tutorial, you downloaded the Vue CLI and created your own single-file components with AppHeader.vue and AppFooter.vue. You successfully generated a Vue.js Single Page Application (SPA) with selected features from the initial setup, and learned how all of those pieces come together. In addition, you’ve now reviewed the basic architecture of most SPAs and can use that knowledge to futher expand this project.

      Vue.js is a growing ecosystem with a number of tools at your disposable. These tools can help you quickly get started and save time by storing options as a preset. This is just the start of what Vue.js has to offer, but the CLI is perhaps one of the most important tools you will use in your Vue.js journey.

      For more information on Vue.js and Vue CLI 3, it’s recommended to read through their documentation. The CLI tool specifically has many additional features that weren’t covered in this tutorial. For more tutorials on Vue, check out the Vue Topic Page.



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      Handling Authentication In Vue Using Vuex


      Introduction

      Traditionally, many people use local storage to manage tokens generated through client-side authentication. A big concern is always a better way to manage authorization tokens to allow us to store even more information on users.

      This is where Vuex comes in. Vuex manages states for Vue.js applications. It serves as a centralized store for all the components in an application, with rules ensuring that the state can only be mutated in a predictable fashion.

      Sounds like a better alternative to always checking localStorage? Let’s explore it.

      Prerequisites

      1. Node installed on your local system
      2. Knowledge of JavaScript and Vue
      3. Install Vue CLI on your local system.
      4. Read through Vue Authentication And Route Handling Using Vue-router

      If you want to jump straight to the demo code: Go to vue-auth-vuex on GitHub

      Setting up the application modules

      For this project, we want to create a vue application that has vuex and vue-router. We will use the vue cli 3.0 to create a new vue project and select router and vuex from the options.

      Run the following command to set it up:

      $ vue create vue-auth
      

      Follow the dialogue that shows up, add the necessary information and select the options we need and complete the installation.

      Next, install axios:

      $ npm install axios --save
      

      Setup Axios

      We will need axios across many of our components. Let’s set it up at the entry level so we do not have to import it every time we need it.

      Open the ./src/main.js file and add the following:

      [...]
      import store from './store'
      import Axios from 'axios'
      
      Vue.prototype.$http = Axios;
      const token = localStorage.getItem('token')
      if (token) {
        Vue.prototype.$http.defaults.headers.common['Authorization'] = token
      }
      [...]
      

      Now, when we want to use axios inside our component, we can do this.$http and it will be like calling axios directly. We also set the Authorization on axios header to our token, so our requests can be processed if a token is required. This way, we do not have to set token anytime we want to make a request.

      When that is done, let’s set up the server to handle authentication.

      Setting up the server for authentication

      I already wrote about this when explaining how to handle authentication with vue-router. Check out the Setup Node.js Server section of this

      Setup Components

      The Login Component

      Create a file Login.vue in the ./src/components directory. Then, add the template for the login page:

      <template>
       <div>
         <form class="login" @submit.prevent="login">
           <h1>Sign in</h1>
           <label>Email</label>
           <input required v-model="email" type="email" placeholder="Name"/>
           <label>Password</label>
           <input required v-model="password" type="password" placeholder="Password"/>
           <hr/>
           <button type="submit">Login</button>
         </form>
       </div>
      </template>
      

      When you are done, add the data attributes that would bind to the HTML form:

      [...]
      <script>
        export default {
          data(){
            return {
              email : "",
              password : ""
            }
          },
        }
      </script>
      

      Now, let’s add the method for handling login:

      [...]
      <script>
        export default {
          [...]
          methods: {
            login: function () {
              let email = this.email 
              let password = this.password
              this.$store.dispatch('login', { email, password })
             .then(() => this.$router.push('/'))
             .catch(err => console.log(err))
            }
          }
        }
      </script>
      

      We are using a vuex action — login to handle this authentication. We can resolve actions into promises so we can do cool things with them inside our component.

      The Register Component

      Like the component for login, let’s make one for registering users. Start by creating a file Register.vue in the components directory and add the following to it:

      <template>
        <div>
          <h4>Register</h4>
          <form @submit.prevent="register">
            <label for="name">Name</label>
            <div>
                <input id="name" type="text" v-model="name" required autofocus>
            </div>
      
            <label for="email" >E-Mail Address</label>
            <div>
                <input id="email" type="email" v-model="email" required>
            </div>
      
            <label for="password">Password</label>
            <div>
                <input id="password" type="password" v-model="password" required>
            </div>
      
            <label for="password-confirm">Confirm Password</label>
            <div>
                <input id="password-confirm" type="password" v-model="password_confirmation" required>
            </div>
      
            <div>
                <button type="submit">Register</button>
            </div>
          </form>
        </div>
      </template>
      

      Let define the data attributes we will bind to the form:

      [...]
      <script>
        export default {
          data(){
            return {
              name : "",
              email : "",
              password : "",
              password_confirmation : "",
              is_admin : null
            }
          },
        }
      </script>
      

      Now, let’s add the method for handling login:

      [...]
      <script>
        export default {
          [...]
          methods: {
            register: function () {
              let data = {
                name: this.name,
                email: this.email,
                password: this.password,
                is_admin: this.is_admin
              }
              this.$store.dispatch('register', data)
             .then(() => this.$router.push('/'))
             .catch(err => console.log(err))
            }
          }
        }
      </script>
      

      The Secure Component

      Let’s make a simple component that would only display if our user is authenticated. Create the component file Secure.vue and add the following to it:

      <template>
        <div>
          <h1>This page is protected by auth</h1>
        </div>
      </template>
      

      Update The App Component

      Open ./src/App.vue file and add the following to it:

      <template>
        <div id="app">
          <div id="nav">
            <router-link to="/">Home</router-link> |
            <router-link to="/about">About</router-link><span v-if="isLoggedIn"> | <a @click="logout">Logout</a></span>
          </div>
          <router-view/>
        </div>
      </template>
      

      Can you see the Logout link we set to only show up if a user is logged in? Great.

      Now, let’s add the logic behind the log out:

      <script>
        export default {
          computed : {
            isLoggedIn : function(){ return this.$store.getters.isLoggedIn}
          },
          methods: {
            logout: function () {
              this.$store.dispatch('logout')
              .then(() => {
                this.$router.push('/login')
              })
            }
          },
        }
      </script>
      

      We are doing two things — computing the authentication state of the user and dispatching a logout action to our vuex store when a user clicks the logout button. After the log out, we send the user to login page using this.$router.push('/login'). You can change where the user gets sent to if you want.

      That’s it. Let’s make the auth module using vuex.

      Vuex Auth Module

      If you read past the Setup Node.js Server section, you would notice we had to store user auth token in localStorage and we had to retrieve both the token and user information anytime we wanted to check if the user is authenticated. This works, but it is not really elegant. We will rebuild the authentication to use vuex.

      First, let’s setup our store.js file for vuex:

      import Vue from 'vue'
      import Vuex from 'vuex'
      import axios from 'axios'
      
      Vue.use(Vuex)
      
      export default new Vuex.Store({
        state: {
          status: '',
          token: localStorage.getItem('token') || '',
          user : {}
        },
        mutations: {
      
        },
        actions: {
      
        },
        getters : {
      
        }
      })
      

      If you noticed, we have imported vue, vuex and axios, then asked vue to use vuex. This is because we mean serious business here.

      We have defined the attributes of the state. Now the vuex state would hold our authentication status, jwt token and user information.

      Create The Vuex login Action

      Vuex actions are used to commit mutations to the vuex store. We will create a login action that would authenticate a user with the server and commit user credentials to the vuex store. Open the ./src/store.js file and add the following to actions object:

      login({commit}, user){
          return new Promise((resolve, reject) => {
            commit('auth_request')
            axios({url: 'http://localhost:3000/login', data: user, method: 'POST' })
            .then(resp => {
              const token = resp.data.token
              const user = resp.data.user
              localStorage.setItem('token', token)
              axios.defaults.headers.common['Authorization'] = token
              commit('auth_success', token, user)
              resolve(resp)
            })
            .catch(err => {
              commit('auth_error')
              localStorage.removeItem('token')
              reject(err)
            })
          })
      },
      

      The login action passes vuex commit helper that we will use to trigger mutations. Mutations make changes to vuex store.

      We are making a call to the server’s login route and returning the necessary data. We store the token on localStorage, then pass the token and user information to auth_success to update the store’s attributes. We also set the header for axios at this point as well.

      We could store the token in vuex store, but if the user leaves our application, all of the data in the vuex store disappears. To ensure we allow the user to return to the application within the validity time of the token and not have to log in again, we have to keep the token in localStorage.

      It’s important you know how these work so you can decide what exactly it is you want to achieve.

      We return a promise so we can return a response to a user after login is complete.

      Create The Vuex register Action

      Like the login action, the register action will work almost the same way. In the same file, add the following in the actions object:

      register({commit}, user){
        return new Promise((resolve, reject) => {
          commit('auth_request')
          axios({url: 'http://localhost:3000/register', data: user, method: 'POST' })
          .then(resp => {
            const token = resp.data.token
            const user = resp.data.user
            localStorage.setItem('token', token)
            axios.defaults.headers.common['Authorization'] = token
            commit('auth_success', token, user)
            resolve(resp)
          })
          .catch(err => {
            commit('auth_error', err)
            localStorage.removeItem('token')
            reject(err)
          })
        })
      },
      

      This works similarly to login action, calling the same mutators as our login and register actions have the same simple goal — get a user into the system.

      Create The Vuex logout Action

      We want the user to have the ability to log out of the system, and we want to destroy all data created during the last authenticated session. In the same actions object, add the following:

      logout({commit}){
        return new Promise((resolve, reject) => {
          commit('logout')
          localStorage.removeItem('token')
          delete axios.defaults.headers.common['Authorization']
          resolve()
        })
      }
      

      Now, when the user clicks to log out, we will remove the jwt token we stored along with the axios header we set. There is no way they can perform a transaction requiring a token now.

      Create The Mutations

      Like I mentioned earlier, mutators are used to change the state of a vuex store. Let’s define the mutators we had used throughout our application. In the mutators object, add the following:

      mutations: {
        auth_request(state){
          state.status="loading"
        },
        auth_success(state, token, user){
          state.status="success"
          state.token = token
          state.user = user
        },
        auth_error(state){
          state.status="error"
        },
        logout(state){
          state.status=""
          state.token = ''
        },
      },
      

      Create The Getters

      We use getter to get the value of the attributes of vuex state. The role of our getter in the situation is to separate application data from application logic and ensure we do not give away sensitive information.

      Add the following to the getters object:

      getters : {
        isLoggedIn: state => !!state.token,
        authStatus: state => state.status,
      }
      

      You would agree with me that this is a neater way to access data in the store.

      Hide Pages Behind Auth

      The whole purpose of this article is to implement authentication and keep certain pages away from a user who is not authentication. To achieve this, we need to know the page the user wants to visit and equally have a way to check if the user is authenticated. We also need a way to say if the page is reserved for only authenticated user or unauthenticated user alone or both. These things are important considerations which, luckily, we can achieve with vue-router.

      Defiing Routes For Authenticated And Unauthenticated Pages

      Open the ./src/router.js file and import what we need for this setup:

      import Vue from 'vue'
      import Router from 'vue-router'
      import store from './store.js'
      import Home from './views/Home.vue'
      import About from './views/About.vue'
      import Login from './components/Login.vue'
      import Secure from './components/Secure.vue'
      import Register from './components/Register.vue'
      
      Vue.use(Router)
      

      As you can see, we have imported vue, vue-router and our vuex store setup. We also imported all the components we defined and set vue to use our router.

      Let’s define the routes:

      [...]
      let router = new Router({
        mode: 'history',
        routes: [
          {
            path: '/',
            name: 'home',
            component: Home
          },
          {
            path: '/login',
            name: 'login',
            component: Login
          },
          {
            path: '/register',
            name: 'register',
            component: Register
          },
          {
            path: '/secure',
            name: 'secure',
            component: Secure,
            meta: { 
              requiresAuth: true
            }
          },
          {
            path: '/about',
            name: 'about',
            component: About
          }
        ]
      })
      
      export default router
      

      Our route definition is simple. For routes requiring authentication, we add extra data to it to enable us identify it when the user tries to access it. This is the essence of the meta attribute added to the route definition. If you are asking ”Can I add more data to this meta and use it?” then I’m pleased to tell you that you are absolutely right ?.

      Handling Unauthorized Access Cases

      We have our routes defined. Now, let’s check for unauthorized access and take action.
      In the router.js file, add the following before the export default router:

      router.beforeEach((to, from, next) => {
        if(to.matched.some(record => record.meta.requiresAuth)) {
          if (store.getters.isLoggedIn) {
            next()
            return
          }
          next('/login') 
        } else {
          next() 
        }
      })
      

      From the article on using vue router for authentication, you can recall we had a really complex mechanism here that grew very big and got very confusing. Vuex has helped us simplify that completely, and we can go on to add any condition to our route. In our vuex store, we can then define actions to check these conditions and getters to return them.

      Handling Expired Token Cases

      Because we store our token in localStorage, it can remain there perpetually. This means that whenever we open our application, it would automatically authenticate a user even if the token has expired. What would happen at most is that our requests would keep failing because of an invalid token. This is bad for user experience.

      Now, open ./src/App.vue file and in the script, add the following to it:

      export default {
        [...]
        created: function () {
          this.$http.interceptors.response.use(undefined, function (err) {
            return new Promise(function (resolve, reject) {
              if (err.status === 401 && err.config && !err.config.__isRetryRequest) {
                this.$store.dispatch(logout)
              }
              throw err;
            });
          });
        }
      }
      

      We are intercepting axios call to determine if we get 401 Unauthorized response. If we do, we dispatch the logout action and the user gets logged out of the application. This takes them to the login page like we designed earlier and they can log in again.

      We can agree that this will greatly improve the user’s experience.

      Conclusion

      Using vuex allows us to store and manage authentication state and proceed to check state in our application using only a few lines of code.



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