Vue.js Components Tutorial

Elliot Forbes ⏰ 5 Minutes 📅 Mar 1, 2018

This Tutorial builds off the starter application that we generated in the Getting Started with VueJS article.

Video Tutorial

This tutorial is also available in video format if you wish to watch it!

Introduction

In this tutorial, we are going to look at how you can work with components within your VueJS applications. We are going to start at looking at very simple components and then move on to your standard .vue file components.

The official documentation for VueJS components can be found here: VueJS Components Guide

Goals

By the end of this tutorial, you will be able to define your own components in Vue.JS using either the JavaScript Vue.component function, or contained within .vue component files.

What is A Component?

A component within a VueJS application, is a self-contained unit of code that represents a logical block of your application. Like for example, say you had a dashboard with 4 distinct boxes showing 4 distinct metrics, you would typically want to make each of these 4 boxes a unique component.

The advantages of this are two-fold:

You could easily re-use these components in a different page by just inserting the component’s HTML tag into your other page and, ta-da, it’s there and working.
It also helps in terms of separation of concerns. You don’t want any changes you make in Component A impacting Component B. By having these defined as 2 separate components, you typically have an added level of safety when making any changes.

A Basic Component

Let’s start off by creating a very simple component. We can register this globally by using the Vue.component(tagName, options) like so:

Vue.component('simple-component', {
    // All of my components options
})

// followed by my vue instance:
var vue = new Vue({
    ...
})

Should you wish, we can also register components locally instead of globally as we have done above. This makes the component only available within the scope of another instance and/or component by registering it with the components instance option:

var Child = {
  template: "<div><h2>Hello World</h2></div>"
};

var app = new Vue({
  components: {
    "my-awesome-component": Child
  }
  // all my other vue instance code
});

Once we’ve registered our component, we can then drop it into our VueJS application with the tagName.

<div id="myapp">
  <!-- We can add our component to our app like so -->
  <simple-component></simple-component>
</div>

The Data Function

In the previous tutorial, we created a Vue instance which featured a data object with a msg within it. One of the key things to note when starting to rearchitect your Vuejs to use components, is that data must be a function within your components.

You can certainly still define data as an object but you will see a number of error warnings in the console and a number of weird side effects in you application, such as one component impacting the data within another.

Component.vue files

Now, whilst this is how you would define a basic component, I typically never use this method within my Vue.JS applications. If you are doing anything serious with VueJS then you will tend to find yourself using .vue files to encapsulate your components.

One of the coolest things about Vue.JS is the fact that you can define a component in one .vue file. This .vue file includes the HTML, the JavaScript and the CSS for this one component. These are contained within their own tags:

<template> - The template tag contains the component’s HTML markup.
<script> - The script tag contains the component’s JavaScript code. Within this we can do things like import other components, or other packages we need for our component to work
<style> - The style tag contains all of our component’s rules for styling said component.

If you are coming from an AngularJS or Angular background then you may be used to having a component defined as like 4 distinct files which can lead to thousands of files within your production applications.

Vue.JS seriously helps to minimize this and this encapsulation means that your project directories end up looking more succinct and cleaner and I’m a huge fan of that.

I would highly recommend using the vue-cli in order to generate your applications as it allows you to easily use .vue files within your Vue.JS applications.

Defining a Simple Component

Note - This section assumes you have set up your Vue.JS application using the vue cli. If you would like to see how this is done, please check out my other tutorial here: Getting Started with Vue.JS

Below you’ll find a very simple component that lives within the simple-component.vue file. It features everything our simple-component needs in terms of you HTML, the JavaScript, and the css:

src/components/SimpleComponent.vue

<template>
  <p>All of your components html goes inside these template tags</p>
</template>

<script>
  // All of your components JS code lives within this section
  // we can still do things such as `import lib from 'lib'` should we wish
  export default {
    name: "simple-component",
    data() {
      return {
        msg: "My Profile Component"
      };
    }
  };
</script>

<style scoped>
  p {
    background-color: blue;
  }
</style>

With this in place, you are now able to import this new component into your src/App.vue root component like so:

/src/App.vue

<template>
  <div id="app">
    <img alt="Vue logo" src="./assets/logo.svg">
    <HelloWorld msg="Welcome to Your Vue.js App"/>
    <simple-component/>
  </div>
</template>

<script>
import HelloWorld from './components/HelloWorld.vue'
import SimpleComponent from './components/SimpleComponent.vue';

export default {
  name: 'app',
  components: {
    HelloWorld,
    SimpleComponent
  }
}
</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>

Saving this will cause your Vue.JS project to rebuild automatically if you are running yarn serve or npm run serve. With this rebuilt, you will now see your lovely new <simple-component/> component rendering in its mighty blue glory within your Vue.JS application.

Conclusion

Source Code - The full source code for this tutorial can be found here: TutorialEdge/vuejs-components-tutorial

Hopefully, this article showed you everything you need in order to work with components within your Vue.JS applications. If you need further help then please let me know in the comments section below or by tweeting me: @Elliot_F.