VueJS – FromToSchool

What Is Vuex, And What Is It Used For In VueJS? – A Very Simple Crash Course Tutorial

In jQuery, triggered events were the most important things.

Almost everything that happened, would happen on an onclick, a hover, a keyup/keydown, or some other kind of event.

In Vue, while events sometimes act as triggers in and of themselves, for the most part, the actions that happen within a VueJS UI primarily are triggered by the data within a Vue application, and the changes within that data.

We lay this out in much more detail in our post on VueJS C omponents, but we will go over how this all works briefly below, as a refresher.

VueJS Data And Components – How It All Works

Vue applications, can be thought of as a collection of cascading, UI based, mini-apps. Those mini-apps, coming in the form of relatively self-contained Vue Components.

These mini-apps or components, are all children of the main parent component that initializes all of the others.

This is usually contained within your App.vue file in your Vue application folder directory.

This is a simple diagram that shows you visually what we are talking about here:

[Add a visual diagram here.]

How Data Works, And Flows Within The VueJS Code Structure

In jQuery, data is typically held across the application without much of a predefined structure. It is usually captured by querying an element ID or class and is pretty much globally accessible across the application by default.

In Vue, data is much more self-contained, yet powerful when used.

With a basic Vue application that does not use components, events will have more of the emphasis, as at this point the Vue application is closer to a jQuery application in terms of general, mostly event-driven flow.

As the VueJS application’s complexity increases and components are added, the data-driven aspects of Vue gradually begin to take hold. Simply meaning that as you create a more complex application with Vue, the level of influence that data has within it, rather than events, increases.

Vue data expresses itself most effectively with Components.

The key to this expression comes down to how well the data moves around the application via the use of components.

As the most efficient unit of the UI. Components allow data to flow seamlessly downwards and upwards from parent component to child component.

An example of this will be shown below as you read on.

But what happens when that component of the UI needs to communicate with another, similar component unit?

Then it gets quite complicated.

But before we get into that, let’s first get into how data typically flows up and down Vue Components.

Then we will discuss how data can flow even more efficiently, in any direction you want, whether that is between components or as we have stated above, up and down them.

This increased efficiency will be had with the use of a tool called Vuex.

How VueJS Components Typically Communicate With One Another, Without Vuex

The simplest, standard method of communication across Vue components is between Parent and Child components, communication also occurs between components more directly. We will explore the ways in which components may communicate below.

Vue.js allows component communication in the following ways:-

1. Parent to child communication (Using Props).

This communication is done downwards via the use of ‘props’ which are simply variables that are specific to a particular parent component, and can be inherited by child components.

These are passed into the child Component via the use of Component arguments as well as set within the parent Component instance itself.

We do this setting of the prop within the parent Component instance like this:

[code showing the setting of a prop within the parent component instance]

We may then pass our prop into our child Component with the use of component arguments like this:

[code showing the passing of a prop within the child component instance]

This is how we pass data from our parent Vue Component down to our child Components.

2. Child to parent communication (Using Events).

To pass on data to our child Components, we use a slightly different strategy. Because we are not able to pass props from our child Components up to our parent (props can only be used by the parent component or be inherited by the child).

To get our data up in the other direction towards our parent component, we use events.

The easiest way of doing this is via the use of Vue’s custom $emit event method.

This method can be used from within the child component like so:

[Example of an $emit event being triggered].

It can then be received by the parent Component like this:

[Example of a parent component receiving the child component data via the use of an event]

3. Communication between any component (Using Event Bus).

While the above two methods work well for communication between parent and child components, up and down, if you want to communicate across components you will simply use the Vue ‘event bus’.

The event bus is basically a global event handler and tracker. It keeps tracks of events in a manner that allows any Vue Component to listen and capture them.

To add an event to the event bus, you must simply emit an event from one component and then listen for the corresponding event within the other component:

[code showing addition of an event to the event bus]

Whenever this event is triggered, you may listen to it within any component you want to. Passing in any relevant data along with it.

To listen to an event within a chosen component, you will simply do y:

[code showing the listening of an event]

This method of doing things is ok, but ultimately, firing events all the time just to pass data from component to component is a bit cumbersome.

This becomes especially true when dealing with a relatively large application.

It would be a lot better if there was some sort of global ‘model’ that we could leverage in order to both add or set data, as well as get it whenever we needed it.

Fortunately, this is what Vuex allows us to do.

How Vuex Works Within the Context Of A Vue App

Note: Before jumping into this part, you will have to load Vuex within your application. You may do this via the command line by typing npm install vuex --save from within your project directory.

Within the context of a Vue app, you will use Vuex by first creating a file within which to house your Vuex Store. A “store” is basically a container that holds your application state.

State is basically an object within which the data that is to be used by the components in your application will be held. Those objects essentially being props that are globally accessible for the Vue application to use.

State is an interesting term, because it basically alludes to the data-driven nature of Vue. An application’s functional ‘state’ is defined by the ‘state’ of its data.

The Vue store works in a similar way to a Vue Instance, in that to set it up, and the structure that it uses to work are very similar.

Once this is done, you will simply reference Vuex within your store.js file like this:

[code showing the referencing of the Vuex files, within the store.js file here]

We will here instantiate our Vuex store within the same store.js file like this:

[code showing us instantiating our Vuex store and then adding the state props that we would like to add].

Vuex essentially allows us to store, mutate (manipulate) and then retrieve our data easily and simply via a globally (by all components) accessible store.

The structure here is very simple. At the top of the store we have the actual ‘state’ data. Under that we have our mutations (methods we use to modify our data).

The data that we’ve set within this object can now be accessed by any of our Vue components.

All we have to do is add our ‘store’ option within our root Vue instance. This allows the stored Vuex data to be accessible by all of our components.

There are many things you can do and many ways that you can now play with this data. From manipulating it with mutations to allowing it to be dynamically accessible via the use of ‘getters’.

The key things that Vuex gives you are easy, safe access to global data as well as a bunch of plugins that supercharge what you can do with that data.

This gives you the ability to deal with application data at a higher level of abstraction, and ultimately, makes the development process just that little bit easier.

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What Are Vue Components? A Simple, Crash Course Tutorial

Before you can truly begin to understand Vue Components, you must first understand the Vue Instance. Which is just a JavaScript object that attaches itself to a section of your HTML page, and that initiates the Vue functionality and allows it to run through that section of the page.

In the days when jQuery was most popular, the best way to give a webpage some dynamism was to simply overtake the page with moderate functionality. document.ready function anyone? And then once that was done, to simply bind and then interact with any areas of the page that you needed to.

The problem with this method is as the web’s complexity has increased, and therefore needed more complexity in terms of UI, tools like jQuery, which typically dealth with various sections of the page at once, sometimes with various sections sharing functionality, were now ending up a spaghettified mess. This because there was no modularization and clear seperation of concerns.

Modules prevent spaghetti code.

VueJS and ultimately, Vue Components are a modularization of the previous method of adding interactivity to a webpage. It allows you to target just the segment of the page you need, therefore being able to concentrate more complexity in terms of functionality within that specific area. Ultimately building up a collection of powerful sections that together create a powerful, performant webpage.

Vue Components are simply Vue Instances that you can name and single out specifically, in order to be able to use them in a more modular, flexible fashion. Basically, Vue Components are Vue Instances that you can move around and/or reuse within your UI. Wherever you may need them to be.

They are, if thought of in another way, simply reuseable abstractions of Vue Instances.

Why Vue Components Are Needed

Increasing webpage complexity has over time been met by increasing functionality, as well as modularity, in order to manage that complexity. This means that section by section, the webpage has been made to handle as well to do, more for the user over time. These sections of the page have gradually evolved to become full blown UI modules with the help of JavaScript. With each module within a webpage having more individual power, in order to gradually together increase the power of the entire webpage.

Said another way, webpages have become a bundle of mini-apps. Each section of the page representing not just a paragraph section or a bunch of images, but now representing a complete, modularized mini-application in its own right. In Vue, these are our modularized Vue Instances, or as we’ve named them above, our Vue Components.

Vue Components are a style of creating one of these mini-apps on your page. They are the mini apps that VueJS has developed for us to use.

How Vue Components Work Within The Context Of A Webpage, And A VueJS App

Since Vue Components are simply modularized, abstracted Vue Instances, let’s first start with a Vue Instance and and then build our understanding of Components from there.

A Basic Vue Instance On A Webpage

<div id='app'>{{ someText }}</div>

new Vue({
el: '#app'
data: {
someText: 'helloThereText'
}
})

Things on the web tend to cascade into other things. A ‘web’ as a thing in and of itself is a sort of inverse cascade. So in the same vein, the technologies on this sort of structure will inevitably operate in the same way.

With all technologies used on the web, there is always a root source, or a root initiator. Just like with a spider web, there is a root point where the web began to grow.

VueJS is no different.

When we create our Vue applications, no matter how big or complex they become, the root Vue instance will always be our starting point and where everything in our app, including our Vue components, runs through.

So with this in mind, we will now create our Vue Component.

Creating a Vue Component

Creating a component in Vue is as simple as registering it within Vue and then within your root instance. There are, infact 4 different ways of creating a Vue Component, which are mentioned in the previous link.

But for the purposes of this article, and for simplicity, we will only be covering what we believe is the simplest way. That is to register a Vue Component with a template inside of it.

The way we do this can be seen below:

<div id="app"></div>

const HWComponent = {
	template: `<h1>helloThereText</h1>`,
}
new Vue({
	el: '#app',
	template: ` <div> <HWComponent/> </div> `,
	components: {
		HWComponent
	},
});

Here you can see, we’ve simply replaced our data object with a ‘template’ declaration, where we specify the structure within which our component should be held.

Below that we specify our component. Or components, depending on how many we would like to use.

The registered component, defined in our above const ‘HWComponent’, is now holding our data, the text that is to be displayed.

For most complex Vue apps and projects, the structure as well as the usage of components, is usually within the context of many other components. All of these being routed through a root App.vue component. Which is then also routed through the final, non-component root Vue Instance.

The creation and management of these more complex Vue apps is done via tools like the Vue CLI. You can learn more about that and of how components are usually used within the context of a real world project here: What Is The Vue CLI – A Mini Crash Course Guide.

For now, this short crash course guide should give you a decent enough glimpse of what exactly Vue Components actually are. And how to create them.

From this foundation, you can hopefully go on and continue to build your knowledge base with regard to Vue Compenents, and, to VueJS as a Framework overall.

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What Is The Vue CLI – A Mini Crash Course Guide

As you progress in your level of knowledge with VueJS, you will gradually begin to require more and more horsepower with regard to the tooling that you need in order to get your project set up and running.

For most people who learn VueJS, the path to getting setup typically begins by simply loading in the VueJS library that you need via a CDN in script tags.

After you have started to get the hang of what you can do with Vue and are starting to both understand and need to use the more powerful features that it comes with, such as Vue components (link to a post here about Vue components) and the Vue router, you will begin to see that the amount of setup needed to get up and running is much more than you’d probably like to do with the standard, non-Vue specific method. That being the simple addition of a script tag src, as mentioned above.

This is when you’ll probably start to look into tools like the Vue CLI. A command-line utility that makes the setting up of a Vue project, complete with all the functionality that you need to create a complex modern application as easy as a simple command-line statement:

vue create my-project

Why the Vue CLI is necessary for most Vue projects

Just as construction within human civilization evolved in terms of housing, with more and more complexity being solved by various forms of scaffolding, so in the same vein, as the web evolves, various forms of scaffolding are now needed and being made in order to make the web-based application building process easier.

Compared to jQuery, increasing complexity on the web as time has progressed, as well as what that complexity has necessitated, means that much more is needed in terms of scaffolding, to meet the users’ performance demands.

A highly complex web needs an equally complex response in terms of tooling for web builders.

This is what tools like the command-line utility that is the Vue CLI do for you.

The Vue CLI makes the building of complex coding infrastructures that can manage the new complexity that is now on the web, easier.

Complexity meets complexity, but with a tool like the Vue CLI, that complexity is now simplified for the user.

How To Use The Vue CLI – Step By Step

Before you can get to creating your Vue CLI initiated app, you must first install the Vue CLI from npm.

You do this by typing the following npm command into your terminal:

npm install -g @vue/cli

You may also install it with yarn, if you have that package manager installed, like so:

yarn global add @vue/cli

Once you’ve done this, you may now create your Vue project by typing in the following command:

vue create hello-world

We’ve used ‘hello-world’ here as our project name but you may choose any other name that you like.

That’s all there is to it. You now have installed a complete Vue project.

But what does that mean in terms of what we can now do?

How A Vue CLI initiated App Works, And What It Allows You To Do

Once you’ve installed your Vue project, you’re now probably wondering how it works in terms of the folder structure and what everything in it does.

There are only a few key areas that we will focus on in this tutorial, as this is simply a mini crash course.

These are the main areas that interact within the app, and the ones that you’ll need to focus on most of the time when you’re in the process of development.

The understanding of how these areas within the app work will also allow you to further gain a grounding in Vue.

Before we begin to get into what these key areas are, and the ways in which these key areas work, let’s first take a little look at the overall folder structure in the app we’ve just created.

‘hello-world’ Vue App Folder Structure, The Most Important Parts

The below section are normally within your’src’ folder, inside of your Vue app. This is where your real Vue app lives. And whose contents we will be covering below. In the root directory before you get into src simply is your basic dependency files, such as your ‘node modules’. These are the various key scaffolding elements that are available within your Vue CLI initiated Vue app.

Below, we will simply focus on our Vue app src folder.

[Picture of the Vue App Src folder]

Components

The most important folder to notice here is the ‘components’ folder. This folder holds your Vue components, which are basically self-contained full mini-Vue apps within your overall Vue Application that basically represent a segment of your page. They contain the HTML, CSS, and JavaScript (most of it your Vue code) that you need in order for your Vue functionality to work.

Main.js – The Command Center of Your Vue App

The main.js is the main startup area of your Vue app, where data and processes are routed, it’s here where the main Vue instance is initiated and set ready to go. In most tutorials and by most programmers, you will see a file like this being referred to as your ‘entry’ file, for this reason. This is also where the components that we mentioned previously are connected to the instantiated Vue instance.

App.vue

[picture of App.vue file here.]

App.vue is where we add in and combine the references to all of our app components, as is seen above. We simply add the component element tag name within our main App.vue element and then reference that as one of our instantiated components in our Component’s JavaScript below, within the same file.

This is the file that we then reference within our main.js entry file, in order to load all of our components up.

Assets

We keep our assets such as image files and logos here. For easier referencing from within our app.

On Module Bundlers in the Vue CLI, The Middle Man Of Your App

We mentioned module bundlers above as a standard part of the Vue app creation and running process.

The basic description of a module bundler is as a middle man within your app, that converts the app’s code, which when you’re writing it is not recognizable by the browser that will be running it, down into something that the browser can then run and understand.

The bundling process works by typing in a bundling command on the command line from within your app directory. Like this:

npm run build

This will load the compiled, browser readable files into a /dist folder that can then be used to display your app.

Our /dist folder is where our compiled HTML, js, and CSS is kept once our Vue code has been run through our module bundlers.

All of the above works in order to make your Vue app runnable by most good, modern web browsers.

All of this functionality and the way that it works is available out of the box in the Vue CLI. Once you begin to use the functionality provided, such as the core functionality described above, you will begin to understand the full power of the scaffolding provided by the Vue CLI.

The final feature we will mention in this point, just to show how useful it is, is the Vue CLI serve command.

Like this:

npm run serve

When this is run from within your Vue app directory, it will load up a simple web server and allow you to see your Vue app in action. A link to it on your localhost, along with the relevant port that is running it, will be available on the command line.

Pretty great right?

I hope this gives you a good general overview of what the Vue CLI can do for you. When you start to use it, you will gradually begin to see what it can help you do.

So don’t wait around. Get active with it today, and see just how powerful a scaffolding tool the Vue CLI is.

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What The Vue Instance Is, And How It Unlocks The Magic Of VueJS

What Is The Vue Instance?

Before we can start to do anything with VueJS on our webpage, we first need to create a way for Vue to initialize and then ‘bind’ itself onto that page.

Just as in jQuery, nothing happens until we initialize our document ready function, like this:

$( document ).ready(function() { console.log( "ready!" );});

In Vue, nothing happens until we create our Vue Instance, like this:

<script>
new Vue({
    el: '#app'
    data: {
        
    }
})
</script>

Within the bounds of this Vue Instance, which is just a simple JavaScript object, we can write the code that Vue will recognize and then execute onto the page.

Let’s first take a deeper look into what is actually going on with this Vue instance object, and then we will talk more about what it can allow us to do on our HTML page specifically, and how it unlocks the magic of Vue.

Inside The Vue Instance Object

On the first line, we begin with the instantiation of our class object, which bears the title of Vue, like this:

new Vue({ }}

This creates and initializes the Vue instance within our browser.

Next, within our created Vue instance, on the first line of our object, we add in our ‘el’ option, which looks like this:

new Vue({
    el: '#app'
})

What this ‘el’ option does is simply ‘bind’ our Vue Instance to an element within our HTML (in this case, one with an ID of ‘#app’), allowing us to apply our Vue functionality to everything that is within that element.

Putting it all together, it would look like this:

<div id='app' </div>

new Vue({
    el: '#app'
})

As you can see, our <div> element, with an ID of ‘#app’ has been bound to our newly created Vue Instance. Another way that we can refer to this ‘binding’ of an element by Vue within the Vue instance is as a ‘mounting’ of, or to ‘mount’, an element. It means the same thing. Simply that we have attached our Vue instance to that element, in order to activate Vue’s functionality within that element.

A key difference to note here, coming from jQuery, is that rather than applying functionality to the entire webpage, as is done with jQuery, in Vue, functionality is only applied to a specific section of the page – one that is bound to a Vue instance (of which there can be many). In this case, our <div> element, with an ID of ‘#app’.

Lastly, we have our ‘data’ option. Which as you’ll see soon, is one of the most important parts of our Vue instance in terms of functionality. It looks like this:

new Vue({
    el: '#app'
    data: {
        someText: 'helloThereText'
    }
})

As you can see here, after creating our Vue instance and then mounting it onto our ‘#app’ element, we then set some data within our instance. This gives our mounted <div#app> element access to the data that is within our Vue instance object.

That data can now be used directly within our mounted HTML element, like this:

<div id='app'>{{ someText }}</div>

By placing the data variable from our instance within double curly braces, we allow Vue to recognize and then ‘interpolate’ the data as being from our Vue instance, in the example above. This data is then transformed into the text that it contains within the mounted HTML element.

On page load, the data held within our ‘someText’ variable above will be displayed out onto the loaded page as the text, ‘helloThereText’.

How The Vue Instance Unlocks The Magic Of VueJS

So from the example above, we can see that a Vue Instance is basically an object that is created in order to allow us to attach Vue functionality to our HTML.

Let’s now take a slightly closer look at what the Vue instance is and what it can do. The explanations below will aid you greatly in getting a deeper understanding of what Vue can do for you, and in general, what Vue is all about.

A Data-Driven Approach To UI Manipulation

Because Vue is primarily ‘data-driven’, which means that what happens on the page is simply a reflection of what happens in the data held by Vue, along with the changes to that data, the Vue instance can be thought of as a syncing agent that simply translates changes in the data held by Vue, to changes in our UI. And by doing so, keeps our data -> view connection ‘in sync’.

An example of this can be seen with the way that view allows us to handle conditional logic on our HTML page.

Below we are displaying or hiding an element within our Vue instance, depending on whether or not data (as a variable within our data object) is set to either true or false.

<div id='app'>
    <h1 v-if="is_it_true">{{ someText }}</h1>
</div>

<script>
    new Vue({
        el: '#app',
        data: {
            someText: 'helloThereText',
            is_it_true: true
        },
    });
</script>

In the current way that it is set up (with Vue’s v-if attribute, Vue attributes allow us to add Vue functionality directly to our HTML elements), our h1 shown above will show on page load. With the text ‘helloThereText’.

If we were to change the value held by our is_it_true variable within our data option to false, the h1 will disappear.

This is what we mean when we say that Vue is data-driven. It is driven, and changes on the webpage are made, by what happens in the data that is held by its instances.

The Vue instance, by giving us a simple ‘command center’ where we may set, and when necessary change our data, helps us to unlock the magic that is data-driven Vue.

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