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      Vue

      Getting Started With Vue


      This Tech Talk is free and open to everyone. Register below to get a link to join the live stream or receive the video recording after it airs.

      Date Time RSVP
      October 6, 2021 11:00 a.m.–12:00 p.m. ET / 3:00–4:00 p.m. GMT

      About the Talk

      Vue.js is a fantastic JavaScript framework. It has been chosen by many as an alternative to React. Let’s explore why so many use and love Vue.js.

      What You’ll Learn

      • How to use Vue.js
      • Why Vue.js is better than React for some teams

      This Talk Is Designed For

      JavaScript developers that want to build fast and efficient frontends.

      Resources

      Introduction to Vue.js



      Source link

      How To Create User Interactions with Events in Vue


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

      Introduction

      In Vue.js development, a client’s web browser reads HTML and JavaScript and renders web pages based off of the instructions that the developer writes for it. But the web page or application not only needs to process data; it also needs to process user interactions. To do this, developers use events in JavaScript that execute code when the user interacts with HTML elements.

      An event can capture any user interaction with a user interface button or a physical keyboard or mouse. In JavaScript, you would create event listeners that wait for that event to occur and then execute a block of code. In Vue.js, you are not required to listen for an event; that is done automatically with the v-on: directive.

      In this tutorial, you will use events in Vue to create an application of airport codes. When the user selects an airport code, the app will add that airport to a “favorites” collection. By following along with this project, you will learn what events are, how to use Vue’s built-in events, and how to create your own custom events.

      Prerequisites

      To complete this tutorial, you will need:

      Step 1 — Setting Up the Project

      The first step in this tutorial will be to set up a demo project with some data to display in the view. This will include an array of JavaScript objects that contain airport data and a Vue component to iterate over and render the data.

      First, generate a project using Vue CLI:

      • vue create favorite-airports

      This will create a project named favorite-airports. This tutorial will use Vue 3, so when prompted, select the option Default (Vue 3) ([Vue 3] babel, eslint):

      Output

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

      Once you have created the project, make a directory to hold all of your local data for this project. First, make the new project folder your working directory:

      Next, make a data directory in the src directory:

      In your text editor of choice, open a file called src/data/airports.js. Add the following data to the file:

      favorite-airports/src/data/airports.js

      export default [
        {
          name: 'Cincinnati/Northern Kentucky International Airport',
          abbreviation: 'CVG',
          city: 'Hebron',
          state: 'KY',
        },
        {
          name: 'Seattle-Tacoma International Airport',
          abbreviation: 'SEA',
          city: 'Seattle',
          state: 'WA',
        },
        {
          name: 'Minneapolis-Saint Paul International Airport',
          abbreviation: 'MSP',
          city: 'Bloomington',
          state: 'MN',
        },
        {
          name: 'Louis Armstrong New Orleans International Airport',
          abbreviation: 'MSY',
          city: 'New Orleans',
          state: 'LA',
        },
        {
          name: `Chicago O'hare International Airport`,
          abbreviation: 'ORD',
          city: 'Chicago',
          state: 'IL',
        },
        {
          name: `Miami International Airport`,
          abbreviation: 'MIA',
          city: 'Miami',
          state: 'FL',
        }
      ]
      

      This data is an array of objects consisting of a few airports in the United States. Next, you are going to iterate through this data to generate cards consisting of the name, abbreviation, city, and state properties. When the user clicks on a card, the app will emit an event up to the parent, which will add that airport to a collection of data that will represent your favorite airports.

      Save and close the airport.js file.

      To render the data, create a single-file component (SFC) with the name src/components/AirportCard.vue and open it in your text editor. This component will contain all of the styles and logic for the airport card.

      Add the following contents to the file:

      favorite-airports/src/components/AirportCard.vue

      <template>
        <div class="airport">
          <p>{{ airport.abbreviation }}</p>
          <p>{{ airport.name }}</p>
          <p>{{ airport.city }}, {{ airport.state }}</p>
        </div>
      </template>
      
      <script>
      export default {
        props: {
          airport: {
            type: Object,
            required: true
          }
        }
      }
      </script>
      
      <style scoped>
      .airport {
        border: 3px solid;
        border-radius: .5rem;
        padding: 1rem;
      }
      
      .airport p:first-child {
        font-weight: bold;
        font-size: 2.5rem;
        margin: 1rem 0;
      }
      
      .airport p:last-child {
        font-style: italic;
        font-size: .8rem;
      }
      </style>
      

      This component contains a prop, which in Vue.js is a way to pass data down from a parent component to a child component. The template section then renders this data. For more on single-file components, check out the How To Create Reusable Blocks of Code with Vue Single-File Components tutorial.

      You may notice that there is some CSS included in the code snippet. In the AirportCard.vue component, the wrapper <div> contains the class of airport. This CSS adds some styling to the generated HTML by adding borders to give each airport the appearance of a card. :first-child and :last-child are pseudo-selectors that apply different styling to the first and last p tags in the HTML inside of the div with the class of airport.

      Save the file and exit from your text editor.

      Next, modify the existing App.vue component to iterate through the airports.js data and render a series of AirportCards.vue components. Open src/App.vue in your text editor and replace the contents with the following highlighted code:

      favorite-airports/src/App.vue

      <template>
        <div class="wrapper">
          <div v-for="airport in airports" :key="airport.abbreviation">
            <airport-card :airport="airport" />
          </div>
        </div>
      </template>
      
      <script>
      import { ref } from 'vue'
      import allAirports from '@/data/airports.js'
      import AirportCard from '@/components/AirportCard.vue'
      
      export default {
        components: {
          AirportCard
        },
        setup() {
          const airports = ref(allAirports)
          return { airports }
        }
      }
      </script>
      
      <style>
      #app {
        font-family: Avenir, Helvetica, Arial, sans-serif;
        -webkit-font-smoothing: antialiased;
        -moz-osx-font-smoothing: grayscale;
        text-align: center;
        color: #2c3e50;
        margin-top: 60px;
      }
      
      .wrapper {
        display: grid;
        grid-template-columns: 1fr 1fr 1fr;
        grid-column-gap: 1rem;
        max-width: 960px;
        margin: 0 auto;
      }
      </style>
      

      This imports the data and the SFC, then uses the v-for directive to iterate over the data, creating an airport card for each object in the airport.js array. It also adds additional CSS targeted to the wrapper class, which uses CSS grid to manage the layout of the cards.

      Save and exit the file. With the project now set up, run a local development server with the following command:

      This will start a server on your localhost, usually on port :8080. Open your web browser of choice and visit localhost:8080 to find the following:

      A view of the airport data rendered on cards, with the airport abbreviation, full name, and location rendered in black, sans-serif font.

      Now that you have your sample project set up, you’ll next explore built-in events using the v-on directive. When this event is fired, an alert pop-up box will appear with the airport code of the airport associated with that event.

      Step 2 — Listening for Events With the v-on Directive

      As stated earlier, events are a way to execute functions when the user interacts with HTML elements in the DOM (Document Object Model). When writing vanilla JavaScript, to execute a function on an event, you may write something called an event listener. An event listener is a function that waits for that interaction to occur, then executes some code. With Vue, however, you can use the v-on directive for this purpose. A directive is a piece of re-useable code that a developer can use in order to manipulate the DOM. The v-on directive is provided by Vue.js out of the box.

      In this step, you will create a function in your application that runs when a user clicks on a card. Open the src/components/AirportCard.vue component in your text editor of choice.

      Create a function that alerts the user of the airport that they clicked on by adding the following highlighted code:

      favorite-airports/src/components/AirportCard.vue

      ...
      <script>
      export default {
        props: {
          airport: {
            type: Object,
            required: true
          }
        },
        setup() {
          function selectAirport(airport) {
            alert(`You clicked on ${airport.abbreviation}. It's located in ${airport.city}, ${airport.state}.`)
          }
      
          return { selectAirport }
        }
      }
      </script>
      ...
      

      In Vue.js 3, reactive functions need to be defined and exported in the setup component method. This tells Vue that it can execute the selectAirport function in the <template>.

      With the function defined, you’ll now attach it to an event on an HTML element. As stated before, you can use the v-on directive and attach an event with the name of click; this is an event provided by Vue.js. In the AirportCard.vue component, add the v-on directive to the wrapper <div>:

      favorite-airports/src/components/AirportCard.vue

      <template>
        <div class="airport" v-on:click="selectAirport(airport)">
          <p>{{ airport.abbreviation }}</p>
          <p>{{ airport.name }}</p>
          <p>{{ airport.city }}, {{ airport.state }}</p>
        </div>
      </template>
      ...
      

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

      Now, when you click on a card, an alert will pop-up with the message provided. If you click on CVG for example, you will find the following:

      Vue site with alert pop-up that reads "localhost:8080 says You clicked on CVG. It's located in Hebron, KY."

      The click event is not the only event that is provided to you out-of-the-box by Vue.js. In fact, you can use v-on any native JavaScript event, like:

      • keyup
      • mouseover
      • focus
      • mouseenter
      • change

      Next, you will change this v-on:click listener to mouseover to illustrate how Vue.js listens for events. mouseover is an event that fires whenever a mouse cursor moves over an HTML element.

      Open up src/components/AirportCard.vue again and update your file with the following highlighted code:

      favorite-airports/src/components/AirportCard.vue

      <template>
        <div class="airport" @mouseover="selectAirport(airport)">
          <p>{{ airport.abbreviation }}</p>
          <p>{{ airport.name }}</p>
          <p>{{ airport.city }}, {{ airport.state }}</p>
        </div>
      </template>
      

      As shown here, Vue also has shorthand syntax for v-on: events. To use the shorthand syntax, you replaced v-on with @. Save and exit the file.

      Now when you visit localhost:8080 and hover over a card, that function will execute and display a native alert.

      This functionality is good for testing purposes, but may be undesired since it displays the alert every time a user hovers over it. A better experience might be to only display it the first time a user hovers over that card. In vanilla JavaScript, you may track the amount of times a user hovers over a card, then prevent further executions. Vue.js has event modifiers that you can leverage to accomplish the same thing with less code.

      In the next section, you are going to explore event modifiers and use them for a better user experience.

      Step 3 — Using Event and Key Modifiers

      In the previous section, you executed a function on the click and mouseover events. You also learned about the Vue.js shorthand for v-on events. Now you will expand on this further by attaching a modifier to this mouseover event so your function executes only once.

      Vue.js provides a number of event modifiers for you. Some of these include:

      • .stop: stops event propagation
      • .prevent: prevents the HTML element’s default behavior
      • .capture: handles an event targeting an inner element before the selected element
      • .self: only triggers the handler if event.target is the element itself
      • .once: only executes the function once
      • .passive: enables the element’s default behavior to happen immediately instead of waiting for the event, which can be used for optimizing performance for scroll on mobile devices

      In this case, you’ll use the .once modifier. In your text editor, open the AirportCard.vue component and add the modifier to the existing mouseover event:

      favorite-airports/src/components/AirportCard.vue

      <template>
        <div class="airport" @mouseover.once="selectAirport(airport)">
          <p>{{ airport.abbreviation }}</p>
          <p>{{ airport.name }}</p>
          <p>{{ airport.city }}, {{ airport.state }}</p>
        </div>
      </template>
      

      Save the file. Visit your application in the browser and you’ll find that the event only fires once on the first mouseover event.

      Next, you’ll continue exploring modifiers by using key modifiers. These key modifiers are associated with keystroke events, such as keyup. For this next part, imagine that you want to make this clicking action a little more explicit. One way you can do that is by adding a key modifier to the @click event on the .airport <div> in your template.

      To do that, change the @mouseover to @click and add the .shift modifier:

      favorite-airports/src/components/AirportCard.vue

      <template>
        <div class="airport" @click.shift="selectAirport(airport)">
          <p>{{ airport.abbreviation }}</p>
          <p>{{ airport.name }}</p>
          <p>{{ airport.city }}, {{ airport.state }}</p>
        </div>
      </template>
      

      Save the changes and open the application in your browser. If you click on a card without holding the SHIFT key, the alert does nothing. Now, try holding down the SHIFT key when clicking on a card. Your function will now execute, and you will receive an alert.

      In this section, you learned about Vue’s built-in events and the modifiers associated with those events. You can get a lot done with these built-in events, but there will be times when you’ll need to have a custom event. In the next section, you’re going to use custom events to emit an action up to a parent so that it will execute a function.

      Step 4 — Creating Custom Events

      When developing applications in Vue.js, there will be times when you need to pass data up to a parent component via a custom event. Props are read-only data that are passed down to a child from the parent, but a custom action via an $emit is the opposite of that. To create the most reusable components, it’s best to think of these as functions. You pass data down through props (arguments), and emit values back up to the parent (a return value).

      To emit an event from the child component to the parent, you use the $emit function. Before implementing this, this tutorial will guide you through an example to demonstrate how this works.

      The $emit function accepts two arguments: the action name (a string), and the value to pass up to the parent. In the following example, when the user clicks on the button, you are sending the value CVG to the parent component under the action favoriteAirport:

      ChildComponent.vue

      <template>
        <button @click="$emit('favoriteAirport', 'CVG')">A button</button>
      </template>
      

      In the parent component, you would use the v-on directive and listen for the favoriteAirport event. When this custom event is fired, the code will do something with the value:

      ParentComponent.vue

      <template>
        <child-component @favoriteAirport="favoriteAirport = $event" />
      </template>
      
      <script>
      import { ref } from 'vue'
      export default {
        setup() {
          const favoriteAirport = ref('')
      
          return { favoriteAirport }
        }
      }
      </script>
      

      The value of the event will be $event. In this case, $event is actually CVG, which you then store in a reactive data property called favoriteAirport.

      Now that you know what a custom event looks like, you will put it into practice by implementing this custom event into your application.

      Open the AirportCards.vue component in your text editor. In the @click event, remove the reference to the function and replace it with $emit("favoriteAirport", airport). Remember, the first arugment is the name of the event and the second is the value that you are emitting:

      favorite-airports/src/components/AirportCard.vue

      <template>
        <div class="airport" @click="$emit('favoriteAirport', airport)">
          <p>{{ airport.abbreviation }}</p>
          <p>{{ airport.name }}</p>
          <p>{{ airport.city }}, {{ airport.state }}</p>
        </div>
      </template>
      ...
      

      Save the file. Now, when the user clicks on the airport card, a custom event will fire and pass up that airport object.

      Next, open src/App.vue to add some HTML to the template. You will show the favorite airports list after the six cards that are already present:

      favorite-airports/src/App.vue

      <template>
        <div class="wrapper">
          <div v-for="airport in airports" :key="airport.abbreviation">
            <airport-card :airport="airport" />
          </div>
          <h1 v-if="favoriteAirports.length">Favorite Airports</h1>
          <div v-for="airport in favoriteAirports" :key="airport.abbreviation">
            <airport-card :airport="airport" />
         </div>
        </div>
      </template>
      
      <script>
      import { ref } from 'vue'
      import allAirports from '@/data/airports.js'
      import AirportCard from '@/components/AirportCard.vue'
      
      export default {
        components: {
          AirportCard
        },
        setup() {
          const airports = ref(allAirports)
          const favoriteAirports = ref([])
      
          return { airports, favoriteAirports }
        }
      }
      </script>
      ...
      

      In this code snippet, you are creating a reactive data property called favoriteAirports, which is an empty array. In the <template>, you iterate through the empty array to render the <airport-card /> components, much like you did in an earlier step.

      Now you need to add the v-on event for your custom event:

      favorite-airports/src/App.vue

      <template>
        <div class="wrapper">
          <div v-for="airport in airports" :key="airport.abbreviation">
            <airport-card :airport="airport" @favoriteAirport="favoriteAirports.push($event)" />
          </div>
          <h1 v-if="favoriteAirports.length">Favorite Airports</h1>
          <div v-for="airport in favoriteAirports" :key="airport.abbreviation">
            <airport-card :airport="airport" />
         </div>
        </div>
      </template>
      ...
      

      In the @favoriteAiport custom event, you used the JavaScript push() method to add the airport from the child ($event) to the favoriteAirports reactive data property.

      Open you browser and navigate to your project at localhost:8080. When you click on one of the airport cards, that card will appear under Favorite Airports.

      Vue airport app with a list of favorite airports that includes the CVG airport card.

      In this section, you learned about custom events, what they are, and how to use them. A custom event is a way to pass data up to a parent component through the $emit function provided by Vue. Once that data has been emitted, you can further manipulate it in the parent component, like adding it to an array.

      Conclusion

      In this tutorial, you learned how Vue.js listens for a number of built-in events, such as click and mouseover. In addition to that, you tried out event and key modifiers, small pieces of code that you appended to your event to provide additional functionality. With this, you set up your app to execute the function once with the .once modifier and to only fire when holding down the SHIFT key using the .shift modifier.

      Vue provides an efficient way to listen for events that lets you focus on manipulating data over manually setting up event listeners. In addition to that, Vue allows you to think of components as functions: They accept data props and can return a value with $emit.

      To learn more about Vue components, it is recommended to read through the Vue documentation. For more tutorials on Vue, check out the How To Develop Websites with Vue.js series page.



      Source link

      How To Create Reusable Blocks of Code with Vue Single-File Components


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

      Introduction

      When creating a web application using Vue.js, it’s a best practice to construct your application in small, modular blocks of code. Not only does this keep the parts of your application focused, but it also makes the application easier to update as it grows in complexity. Since an app generated from the Vue CLI requires a build step, you have access to a Single-File Components (SFC) to introduce modularity into your app. SFCs have the .vue extension and contain an HTML <template>, <script>, and <style> tags and can be implemented in other components.

      SFCs give the developer a way to create their own HTML tags for each of their components and then use them in their application. In the same way that the <p> HTML tag will render a paragraph in the browser, and hold non-rendered functionality as well, the component tags will render the SFC wherever it is placed in the Vue template.

      In this tutorial, you are going to create a SFC and use props to pass data down and slots to inject content between tags. By the end of this tutorial, you will have a general understanding of what SFCs are and how to approach code re-usability.

      Prerequisites

      Step 1 — Setting Up the Project

      In this tutorial, you are going to be creating an airport card component that displays a number of airports and their codes in a series of cards. After following the Prerequisites section, you will have a new Vue project named sfc-project. In this section, you will import data into this generated application. This data will be an array of objects consisting of a few properties that you will use to display information in the browser.

      Once the project is generated, open your terminal and cd or change directory into the root src folder:

      From there, create a new directory named data with the mkdir command, then create a new file with the name us-airports.js using the touch command:

      • mkdir data
      • touch data/us-airports.js

      In your text editor of choice, open this new JavaScript file and add in the following local data:

      sfc-project/data/us-airports.js

      export default [
        {
          name: 'Cincinnati/Northern Kentucky International Airport',
          abbreviation: 'CVG',
          city: 'Hebron',
          state: 'KY'
        },
        {
          name: 'Seattle-Tacoma International Airport',
          abbreviation: 'SEA',
          city: 'Seattle',
          state: 'WA'
        },
        {
          name: 'Minneapolis-Saint Paul International Airport',
          abbreviation: 'MSP',
          city: 'Bloomington',
          state: 'MN'
        }
      ]
      

      This data is an array of objects consisting of a few airports in the United States. This will be rendered in a Single-File Component later in the tutorial.

      Save and exit the file.

      Next, you will create another set of airport data. This data will consist of European airports. Using the touch command, create a new JavaScript file named eu-airports.js:

      • touch data/eu-airports.js

      Then open the file and add the following data:

      sfc-project/data/eu-airports.js

      export default [
        {
          name: 'Paris-Charles de Gaulle Airport',
          abbreviation: 'CDG',
          city: 'Paris',
          state: 'Ile de France'
        },
        {
          name: 'Flughafen München',
          abbreviation: 'MUC',
          city: 'Munich',
          state: 'Bavaria'
        },
        {
          name: 'Fiumicino "Leonardo da Vinci" International Airport',
          abbreviation: 'FCO',
          city: 'Rome',
          state: 'Lazio'
        }
      ]
      

      This set of data is for European airports in France, Germany, and Italy, respectively.

      Save and exit the file.

      Next, in the root directory, run the following command in your terminal to start your Vue CLI application running on a local development server:

      This will open the application in your browser on localhost:8080. The port number may be different on your machine.

      Visit the address in your browser. You will find the following start up screen:

      Vue default template page

      Next, start a new terminal and open your App.vue file in your src folder. In this file, delete the img and HelloWorld tags in the <template> and the components section and import statement in the <script>. Your App.vue will resemble the following:

      sfc-project/src/App.vue

      <template>
      
      </template>
      
      <script>
      export default {
        name: 'App',
      }
      </script>
      
      <style>
      #app {
        font-family: Avenir, Helvetica, Arial, sans-serif;
        -webkit-font-smoothing: antialiased;
        -moz-osx-font-smoothing: grayscale;
        text-align: center;
        color: #2c3e50;
        margin-top: 60px;
      }
      </style>
      

      After this, import the us-airports.js file that you created earlier. In order to make this data reactive so you can use it in the <template>, you need to import the ref function from vue. You will need to return the airport reference so the data can be used in the HTML template.

      Add the following highlighted lines:

      sfc-project/src/App.vue

      <template>
        <div class="wrapper">
          <div v-for="airport in airports" :key="airport.abbreviation" class="card">
            <p>{{ airport.abbreviation }}</p>
            <p>{{ airport.name }}</p>
            <p>{{ airport.city }}, {{ airport.state }}</p>
          </div>
        </div>
      </template>
      
      <script>
      import { ref } from 'vue'
      import data from '@/data/us-airports.js'
      
      export default {
        name: 'App',
        setup() {
          const airports = ref(data)
      
          return { airports }
        }
      }
      </script>
      ...
      

      In this snippet, you imported the data and rendered it using <div> elements and the v-for directive in the template.

      At this point, the data is imported and ready to be used in the App.vue component. But first, add some styling to make the data easier for users to read. In this same file, add the following CSS in the <style> tag:

      sfc-project/src/App.vue

      ...
      <style>
      #app { ... }
      
      .wrapper {
        display: grid;
        grid-template-columns: 1fr 1fr 1fr;
        grid-column-gap: 1rem;
        max-width: 960px;
        margin: 0 auto;
      }
      
      .card {
        border: 3px solid;
        border-radius: .5rem;
        padding: 1rem;
        margin-bottom: 1rem;
      }
      
      .card p:first-child {
        font-weight: bold;
        font-size: 2.5rem;
        margin: 1rem 0;
      }
      
      .card p:last-child {
        font-style: italic;
        font-size: .8rem;
      }
      </style>
      

      In this case, you are using CSS Grid to compose these cards of airport codes into a grid of three. Notice how this grid is set up in the .wrapper class. The .card class is the card or section that contains each airport code, name, and location. If you would like to learn more about CSS, check out our How To Style HTML with CSS.

      Open your browser and navigate to localhost:8080. You will find a number of cards with airport codes and information:

      Three airport cards rendering the data for the US airports dataset

      Now that you have set up your initial app, you can refactor the data into a Single-File Component in the next step.

      Step 2 — Creating a Single-File Component

      Since Vue CLI uses Webpack to build your app into something the browser can read, your app can use SFCs or .vue files instead of plain JavaScript. These files are a way for you to create small blocks of scalable and reusable code. If you were to change one component, it would be updated everywhere.

      These .vue components usually consist of these three things: <template>, <script>, and <style> elements. SFC components can either have scoped or unscoped styles. When a component has scoped styles, that means the CSS between the <style> tags will only affect the HTML in the <template> in the same file. If a component has un-scoped styles, the CSS will affect the parent component as well as its children.

      With your project successfully set up, you are now going to break these airport cards into a component called AirportCards.vue. As it stands now, the HTML in the App.vue is not very reusable. You will break this off into its own component so you can import it anywhere else into this app while preserving the functionality and visuals.

      In your terminal, create this .vue file in the components directory:

      • touch src/components/AirportCards.vue

      Open the AiportCards.vue component in your text editor. To illustrate how you can re-use blocks of code using components, move most of the code from the App.vue file to the AirportCards.vue component:

      sfc-project/src/components/AirportCards.vue

      <template>
        <div class="wrapper">
          <div v-for="airport in airports" :key="airport.abbreviation" class="card">
            <p>{{ airport.abbreviation }}</p>
            <p>{{ airport.name }}</p>
            <p>{{ airport.city }}, {{ airport.state }}</p>
          </div>
        </div>
      </template>
      
      <script>
      import { ref } from 'vue'
      import data from '@/data/us-airports.js'
      
      export default {
        name: 'Airports',
        setup() {
          const airports = ref(data)
      
          return { airports }
        }
      }
      </script>
      
      <style scoped>
      .wrapper {
        display: grid;
        grid-template-columns: 1fr 1fr 1fr;
        grid-column-gap: 1rem;
        max-width: 960px;
        margin: 0 auto;
      }
      
      .card {
        border: 3px solid;
        border-radius: .5rem;
        padding: 1rem;
        margin-bottom: 1rem;
      }
      
      .card p:first-child {
        font-weight: bold;
        font-size: 2.5rem;
        margin: 1rem 0;
      }
      
      .card p:last-child {
        font-style: italic;
        font-size: .8rem;
      }
      </style>
      

      Save and close the file.

      Next, open your App.vue file. Now you can clean up the App.vue component and import AirportCards.vue into it:

      sfc-project/src/App.vue

      <template>
        <AirportCards />
      </template>
      
      <script>
      import AirportCards from '@/components/Airports.vue'
      
      export default {
        name: 'App',
        components: {
          AirportCards
        }
      }
      </script>
      
      <style scoped>
      #app {
        font-family: Avenir, Helvetica, Arial, sans-serif;
        -webkit-font-smoothing: antialiased;
        -moz-osx-font-smoothing: grayscale;
        text-align: center;
        color: #2c3e50;
        margin-top: 60px;
      }
      </style>
      

      Now that AirportCards is a standalone component, you have put it in the <template> HTML as you would a <p> tag.

      When you open up localhost:8080 in your browser, nothing will change. The same three airport cards will still display, because you are rendering the new SFC in the <AirportCards /> element.

      Next, add this same component in the template again to illustrate the re-usability of components:

      /src/App.vue

      <template>
        <AirportCards />
        <airport-cards />
      </template>
      ...
      

      You may notice that this new instance of AirportCards.vue is using kebab-case over PascalCase. When referencing components, Vue does not care which one you use. All capitalized words and letters will be separated by a hyphen and will be lower case. The same applies to props as well, which will be explained in the next section.

      Note: The case that you use is up to personal preference, but consistency is important. Vue.js recommends using kebab-case as it follows the HTML standard.

      Open the browser and visit localhost:8080. You will find the cards duplicated:

      The US airport cards rendered twice in the browser.

      This adds modularity to your app, but the data is still static. The row of cards is useful if you want to show the same three airports, but changing the data source would require changing the hard-coded data. In the next step, you are going to expand this component further by registering props and passing data from the parent down to the child component.

      Step 3 — Leveraging Props to Pass Down Data

      In the previous step, you created an AirportCards.vue component that rendered a number of cards from the data in the us-airports.js file. In addition to that, you also doubled the same component reference to illustrate how you can easily duplicate code by adding another instance of that component in the <template>.

      However, leaving the data static will make it difficult to change the data in the future. When working with SFCs, it can help if you think of components as functions. These functions are components that can take in arguments (props) and return something (HTML). For this case, you will pass data into the airports parameter to return dynamic HTML.

      Open the AirportCards.vue component in your text editor. You are currently importing data from the us-airports.js file. Remove this import statement, as well as the setup function in the <script> tag:

      sfc-project/src/components/AirportCards.vue

      ...
      <script>
      
      export default {
        name: 'Airports',
      }
      </script>
      ...
      

      Save the file. At this point, nothing will render in the browser.

      Next, move forward by defining a prop. This prop can be named anything; it just describes the data coming in and associates it with a name.

      To create a prop, add the props property in the component. The value of this is a series of key/value pairs. The key is the name of the prop, and the value is the description of the data. It’s best to provide as much description as you can:

      sfc-project/src/components/AirportCards.vue

      ...
      <script>
      
      export default {
        name: 'Airports',
        props: {
          airports: {
            type: Array,
            required: true
          }
        }
      }
      </script>
      ...
      

      Now, in AirportCard.vue, the property airports refers to the data that is passed in. Save and exit from the file.

      Next, open the App.vue component in your text editor. Like before, you will need to import data from the us-airports.js file and import the ref function from Vue to make it reactive for the HTML template:

      sfc-project/src/App.vue

      <template>
        <AirportCards :airports="usAirports" />
        <airport-cards />
      </template>
      
      <script>
      import { ref } from 'vue'
      import AirportCards from '@/components/Airports.vue'
      import usAirportData from '@/data/us-airports.js'
      
      export default {
        name: 'App',
        components: {
          AirportCards
        },
        setup() {
          const usAirports = ref(usAirportData)
      
          return { usAirports }
        }
      }
      </script>
      

      If you open your browser and visit localhost:8080, you will find the same US airports as before:

      US airports rendered on cards in the browser

      There is another AirportCards.vue instance in your template. Since you defined props within that component, you can pass any data with the same structure to render a number of cards from different airports. This is where the eu-airports.js file from the initial setup comes in.

      In App.vue, import the eu-airports.js file, wrap it in the ref function to make it reactive, and return it:

      /src/App.vue

      <template>
        <AirportCards :airports="usAirports" />
        <airport-cards :airports="euAirports" />
      </template>
      
      <script>
      ...
      import usAirportData from '@/data/us-airports.js'
      import euAirportData from '@/data/eu-airports.js'
      
      export default {
        ...
        setup() {
          const usAirports = ref(usAirportData)
          const euAirports = ref(euAirportData)
      
          return { usAirports, euAirports }
        }
      }
      </script>
      ...
      

      Open your browser and visit localhost:8080. You will find the European airport data rendered below the US airport data:

      US airport data rendered as cards, followed by European airport data rendered in the same way.

      You have now successfully passed in a different dataset into the same component. With props, you are essentially re-assigning data to a new name and using that new name to reference data in the child component.

      At this point, this application is starting to become more dynamic. But there is still something else that you can do to make this even more focused and re-usable. In Vue.js, you can use something called slots. In the next step, you are going to create a Card.vue component with a default slot that injects the HTML into a placeholder.

      Step 4 — Creating a General Card Component Using Slots

      Slots are a great way to create re-usable components, especially if you do not know if the HTML in that component will be similar. In the previous step, you created another AirportCards.vue instance with different data. In that example, the HTML is the same for each. It’s a <div> in a v-for loop with paragraph tags.

      Open your terminal and create a new file using the touch command. This file will be named Card.vue:

      • touch src/components/Card.vue

      In your text editor, open the new Card.vue component. You are going to take some of the CSS from AirportCards.vue and add it into this new component.

      Create a <style> tag and add in the following CSS:

      sfc-project/src/components/Card.vue

      <style>
      .card {
        border: 3px solid;
        border-radius: .5rem;
        padding: 1rem;
        margin-bottom: 1rem;
      }
      </style>
      

      Next, create the HTML template for this component. Before the <style> tag, add a <template> tag with the following:

      sfc-project/src/components/Card.vue

      <template>
        <div class="card">
      
        </div>
      </template>
      ...
      

      In between the <div class="card">, add the <slot /> component. This is a component that is provided to you by Vue. There is no need to import this component; it is globally imported by Vue.js:

      sfc-project/src/components/Card.vue

      <template>
        <div class="card">
          <slot />
        </div>
      </template>
      

      This slot is a placeholder for the HTML that is between the Card.vue component’s tags when it is referenced elsewhere.

      Save and exit the file.

      Now go back to the AirportCards.vue component. First, import the new Card.vue SFC you just created:

      sfc-project/src/components/AirportCards.vue

      ...
      <script>
      import Card from '@/components/Card.vue'
      
      export default {
        name: 'Airports',
        props: { ... },
        components: {
          Card
        }
      }
      </script>
      ...
      

      Now all that is left is to replace the <div> with <card>:

      /src/components/AirportCards.vue

      <template>
        <div class="wrapper">
          <card v-for="airport in airports" :key="airport.abbreviation">
            <p>{{ airport.abbreviation }}</p>
            <p>{{ airport.name }}</p>
            <p>{{ airport.city }}, {{ airport.state }}</p>
          </card>
        </div>
      </template>
      ...
      

      Since you have a <slot /> in your Card.vue component, the HTML between the <card> tags is injected in its place while preserving all styles that have been associated with a card.

      Save the file. When you open your browser at localhost:8080, you will find the same cards that you’ve had previously. The difference now is that your AirportCards.vue now reference the Card.vue component:

      US airport data rendered as cards, followed by European airport data rendered in the same way.

      To show the power of slots, open the App.vue component in your application and import the Card.vue component:

      sfc-project/src/App.vue

      ...
      <script>
      ...
      import Card from '@/components/Card.vue'
      
      export default {
        ...
        components: {
          AirportCards,
          Card
        },
        setup() { ... }
      }
      </script>
      ...
      

      In the <template>, add the following under the <airport-cards /> instances:

      sfc-project/src/App.vue

      <template>
        <AirportCards :airports="usAirports"/>
        <airport-cards :airports="euAirports" />
        <card>
          <p>US Airports</p>
          <p>Total: {{ usAirports.length }}</p>
        </card>
        <card>
          <p>EU Airports</p>
          <p>Total: {{ euAirports.length }}</p>
        </card>
      </template>
      ...
      

      Save the file and visit localhost:8080 in the browser. Your browser will now render additional elements displaying the number of airports in the datasets:

      US and European airports displayed, along with two cards that display that there are three airports in each dataset

      The HTML between the <card /> tags is not exactly the same, but it still renders a generic card. When leveraging slots, you can use this functionality to create small, re-usable components that have a number of different uses.

      Conclusion

      In this tutorial, you created single-file components and used props and slots to create reusable blocks of code. In the project, you created an AirportCards.vue component that renders a number of airport cards. You then broke up the AirportCards.vue component further into a Card.vue component with a default slot.

      You ended up with a number of components that are dynamic and can be used in a number of different uses, all while keeping code maintainable and in keeping with the D.R.Y. software principle.

      To learn more about Vue components, it is recommended to ready through the Vue documentation. For more tutorials on Vue, check out the How To Develop Websites with Vue.js series page.



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