Async Vue.js Components - Vue.js Tutorials

Async Vue.js Components - Vue.js Tutorials

In this tutorial, you'll see how to build and lazy load these async components in Vue.js

In this tutorial, you'll see how to build and lazy load these async components in Vue.js

As your application grows, you start to look for performance patterns to make it faster. On the way, you’ll find code splitting and lazy loading to be two of them that make your initial bundle smaller by deferring the loading of code chunks until needed.

Lazy loading makes a lot of sense to be applied to the app routes and has a great impact because each route is a different section of an app.

Another case where lazy loading makes sense is when you have components which rendering is deferred. These components can be tooltips, popovers, modals, etc, and can be used as async components.

Let’s see how to build and lazy load these async components in Vue.

Lazy Loading a Component

Before we start by lazy loading a component, let’s first remember how we usually load a component. For that, let’s create a Tooltip.vue component:

<!-- Tooltip.vue --> 
<template> 
  <h2>Hi from Tooltip!</h2> 
</template>

Nothing special here, it’s just a simple component. We can use it in another component by doing local registration, importing the Tooltip component, and adding it to the components component option. For instance, in an App.vue component:

<!-- App.vue --> 
<template> 
  <div> 
    <tooltip></tooltip> 
  </div> 
</template> 

<script> 
import Tooltip from "./Tooltip"; 

export default { 
  components: { 
    Tooltip 
  } 
}; 
</script>

The Tooltip component is imported, used and loaded as long as the App is imported, probably on the initial load. But think: wouldn’t make sense to load that component only when we’re going to use it? It’s likely that the user navigates through the whole sit without the need of a tooltip.

Why should we spend precious resources on loading the component at the beginning of the application? We can apply a combination of lazy loading and code splitting in order to improve that. Lazy loading is the technique of loading something at a later phase when it’s going to be used.

While code splitting is about separating a piece of code in a separate file, known as chunk, so that the initial bundle of your application gets reduced, increasing the initial load.

Vue makes it easy to apply these techniques by using the language standard dynamic import, a JavaScript feature likely landing on the ES2018 version of the language that allows loading a module in runtime. We’ll have a separate article to dive deep into these concepts, but let’s see it from a practical and simple perspective.

Modern bundlers, such as Webpack (since version 2), Rollup and Parcel will understand this syntax and automatically create a separate file for that module which will load when it’s required.

I can imagine you’re already familiar with importing a module the usual static way. However the dynamic import is a function that returns a promise, containing the module as its payload. The following example shows how to import the utils module, both in a static and lazy-loaded dynamic way:

// static import 
import utils from "./utils"; 

// dynamic import 
import("./utils").then(utils => { 
  // utils module is available here... 
});

Lazy loading a component in Vue is as easy as importing the component using dynamic import wrapped in a function. In the previous example, we can lazy load the Tooltip component as follows:

export default { 
  components: { 
    Tooltip: () => import("./Tooltip") 
  } 
};

That’s it, just by passing () => import("./tooltip") instead of the previous import Tooltip from "./tooltip" Vue.js will lazy load that component as soon as is requested to be rendered.

Not only that, but it will apply code splitting as well. You can test that by running that code using any of the bundlers mentioned. An easy way is by using the vue-cli, but at the end of the article, you’ll find an already built demo. Once running, open the dev tools and you’ll see a JavaScript file with a name like 1.chunk.js:

In the previous example, even though we’re lazily loading the Tooltip component, it’ll be loaded as soon as it is required to be rendered, which happens right away when the App component gets mounted.

However, in practice, we’d like to defer the Tooltip component loading until it is required, which usually happens conditionally after a certain event has been triggered, for example when hovering a button or text.

For simplicity, let’s take the previous App component and add a button to make the Tooltip render conditionally using a v-if condition:

<!-- App.vue --> 
<template> 
  <div> 
    <button @click="show = true">Load Tooltip</button> 
    <div v-if="show"> 
      <tooltip></tooltip> 
    </div> 
  </div> 
</template> 

<script> 
export default { 
  data: () => ({ show: false }), 
  components: { 
    Tooltip: () => import("./Tooltip") 
  } 
}; 
</script>

Keep in mind that Vue doesn’t use a component until it needs to be rendered. Meaning that the component will not be required until that point and that’s when the component will be lazy loaded.

You can see a demo of this example running in this Codesandbox. Keep in mind that Codesandbox doesn’t do code splitting, so if you want to check that in the dev tools you can download the demo and run it locally on your machine.

User Experience on Async Components

Most of the times, async components load quite fast since they’re small pieces of code chunks stripped out from the main bundle. But imagine you’re lazy loading a big modal component under a very slow connection. That could probably take some seconds to get loaded and rendered.

Sure you can use some optimizations like HTTP caching or resource hints to load it in memory with low priority beforehand, in fact, the new vue-cli applies prefetch to these lazily loaded chunks. Still, in a few cases, it can take some time to load.

From the UX point of view, if a task takes more than 1 second to happen, you start losing user’s attention.

However, the attention could be kept by providing feedback to the user. There are several progress indicator components we could use while loading, in order to engage user’s attention, but how could we use a nice spinner or progress bar while an async component is loading?

Loading Component

Do you remember we’ve used a function with the dynamic import to lazy load an async component?

export default { 
  components: { 
    Tooltip: () => import("./Tooltip"); 
  } 
};

There is a long-hand way to define async components by returning an object instead of the result of the dynamic import. In that object, we can define a loading component:

const Tooltip = () => ({ 
  component: import("./Tooltip"), 
  loading: AwesomeSpinner 
  }
);

In that way, after a default delay of 200ms, the component AwesomeSpinner will be shown. You can customize the delay:

const Tooltip = () => ({ 
  component: import("./Tooltip"), 
  loading: AwesomeSpinner, 
  delay: 500 
});&nbsp;

The component you should use as your loading component must be as small as posible, so that it loads almost instantly.

Error Component

In the same way, we can define an error component in the long-hand form of the lazily loaded component:

const Tooltip = () => ({ 
  component: import("./Tooltip"), 
  loading: AwesomeSpinner, 
  error: SadFaceComponent 
});

The SadFaceComponent will be shown when there is an error loading the "./Tooltip" component. That could happen in several cases:

  • The internet is down
  • That component doesn’t exist (this is a good way to try it, by intentionally deleting it yourself)
  • A timeout is met

By default, there is no timeout, but we can configure it ourselves:

const Tooltip = () => ({ 
  component: import("./Tooltip"), 
  loading: AwesomeSpinner, 
  error: SadFaceComponent, 
  timeout: 5000 
});&nbsp;

Now, if after 5000 milliseconds the component hasn’t load, the error component will be shown.

Wrapping Up

You’ve seen how a component is split in its own chunk file and how it’s lazily loaded using the dynamic import. We’ve also deferred the chunk loading by conditionally rendering it.

While async components can improve an app loading time by splitting and deferring the loading of their chunks, they could have an impact on UX especially when they are big. Having control over the loading state allows us to provide feedback and engage the user in the case when that slowness is noticeable.

What are the differences between the various JavaScript frameworks? E.g. Vue.js, Angular.js, React.js

What are the differences? Do they each have specific use contexts?

What are the differences? Do they each have specific use contexts?

Ember.js vs Vue.js - Which is JavaScript Framework Works Better for You

Ember.js vs Vue.js - Which is JavaScript Framework Works Better for You

In this article we will discuss full details and comparison of both Ember.js and Vue.js

JavaScript was initially created to work for web applications. But today they have become the favorite of mobile app developers. Most of the developers prefer to work with frameworks based on JavaScript. It simplifies coding. You can use JavaScript with almost any framework.

The use of a particular framework will decide how easy and fast it is to create the app. So, you must choose the best one suited for the app that you are planning to build. You must make a wise choice so that you benefit in the end. Among the crowded market, two of the frameworks stand out. We will make a comparison between Ember.js and Vue.js.

Why Do You Select A Particular Framework?

Before we start comparing the two frameworks, we should understand the factors that lead to the choice of a framework. Each developer chooses a framework before he or she goes to work on an app. Let us see the reasons for the selection.

● The codes must be easy to understand and transparent.

● The framework should give the maximum power with the least amount of coding.

● The framework should provide a well laid out structure to work on.

● Does the framework support an in-built router or an external plug-in router?

● The framework should be able to transfer more data on a full page-load so that it becomes a single-page app. A single-page app is more beneficial for the application.

● In single page architectures if there is a need for users to share links to sub-screens within the interface, then the framework should have the capacity to route based on the URL.

● A tighter template option can help in enabling two-way binding.

● The framework should not conflict any third-party library.

● Testing the codes inside the framework should be easy.

● The framework should provide the HTTP client service for AJAX calls

● The documentation is essential. It should be complete and up-to-date.

● The framework should be compatible with the latest version of the browser.

● The framework has to fulfill the above conditions for easy construction of the app. You must ensure that the framework you choose meets the conditions.

Vue.js Explained

Developers are always looking at new frameworks to build their apps. The main requirements are speed and low cost. The framework should be easy to use by even new developers. You should be able to use it at low cost. Other considerations are about simple coding, proper documentation, etc.

Vue.js combines a lot of good when it comes to software language for web app development. The architecture of Vue.js is easy to put in use. The apps developed using Vue.js are easy to integrate with new apps.

Vue.js is a very lightweight framework. It makes it fast to download. It is also much faster than other frameworks. The single-file component nature of the framework is also beneficial. The size has made it very popular.

You can further decrease weight. With Vue.js you can separate the template-to-virtual DOM and compiler. You can only deploy the minified and zipped interpreter which is only 12 KB. You can compile the templates in your machine.

Another significant advantage of Vue.js is that it can integrate easily with existing applications created with JavaScript. It will make it easy for using this framework to make changes to applications already present.

Vue.js also integrates easily with other front-end libraries. You can plug in another library and make up for any deficiency in this framework. This feature makes this tool a versatile one.

Vue.js uses the method of rendering on the streaming-side server. You can render your component and get a readable stream. You can then send this to the HTTP server. It makes the server highly responsive. Your users will get the rendered content very quickly.

Vue.js is very SEO friendly. As the framework supports server-side rendering, the views are rendered directly on the server. The search engines list these.

But the most important thing for you is the ease with which you can learn Vue.js. The structure is elementary. Even new developers will find it easy to use it to build their apps. This framework helps in developing both small and large templates. It helps to save a lot of time.

You can go back and check your errors very easily. You can travel back and inspect all the states apart from testing your components. It is another important feature as far as any developer is concerned.

Vue.js also has very detailed documentation. It helps in writing your applications very quickly. You can build a web page or app with the basic knowledge of HTML or JavaScript.

● Vue.js has pure architecture. It helps in integration with other apps

● Vue.js is lightweight and fast. It can be made lighter by deploying only the interpreter

● You can separate the compiler and the template-to-virtual DOM.

● Due to smooth integration, you can use this to make changes to existing apps

● To make up for any shortfall, you can plug-in any library and makeup.

● As Vue.js uses streaming-side server rendering, your users can get quick responses.

● The server-side rendering also helps in being ranked higher by search engines.

● It has a simple structure. Easy to use for any new developer

● You can go back and check and correct your errors.

● You can check all the existing states.

● Detail documentation also helps build the web page or application very quickly.

Ember.js Decoded

Ember.js is an MVVM model framework. It is open-source software. This platform is mostly used for creating complex multi-page applications. It maintains up-to-date features without discarding any of the old features.

With this framework, you have to follow the architecture of the framework strictly. The JS framework is very tightly organized. It reduces the flexibility that other frameworks might offer.

There is a very refined and developed control system for its platforms and tools. You can integrate it with the new version with the tools provided. There is strict guidance about avoiding outdated APIs.

You can understand Ember’s APIs easily. They are also easy to work. You can make use of highly complex functionalities simply and straightforwardly.

The performance is better as similar jobs are processed together. It creates batches of similar bindings and DOM updates to improve the performance. It means that the browser needs to process them in one go. It will avoid recomputing for each task, wasting a lot of time.

You can write the codes in a simple manner and modules. You can use any of Ember’s APIs. It is possible due to the presence of Promises everywhere.

Ember comes with a well-written guide. The API is recorded in a useful manner. It is a front-end framework that is loaded. Ember has a router, pipeline, services, etc. of its own.

The basis for views, controllers, models, and framework is the Ember Object Model. All components come from the same objects. The framework is firm and steady. The reason is that all elements have similar jobs and characteristics.

Ember has made the general application, organization, and structure clear so that you don’t make any mistakes. You will have no chance to complicate the application unnecessarily. If you have to go out of the defined limits, you will have to force your way out.

The language used for templating in Embers is Handlebars. This language helps Embers to keep its logic out of view. The clean syntax of Handlebars makes it easy for you to read and understand the templates. Handlebar templates are faster to load.

Another advantage you gain from Handlebar is that you don’t have to update your template every time you add or remove data from the page. It will be done automatically by the language itself.

A community that is continually improving the framework supports Ember. They are updating the framework with the latest technology. They also make sure that backward compatibility is possible.

● Ember.js is an open-source MVVM model framework suitable for complex multiple-page applications.

● It offers both the latest and old features.

● It has a very tightly structured framework which doesn’t offer much flexibility

● A very refined control system helps you to integrate with new versions without any problem.

● There is strict guidance about avoiding outdated API versions.

● Ember’s APIs help you to use complex functionalities in a simple manner

● There is no recomputing for each task as the framework allows the browser to do similar functions together.

● Promises allow you to write modular and straightforward code using any API of Ember.js.

● Ember.js is a fully loaded, front-end framework.

● The framework is stable because all components have the same functionalities and properties.

● It has well-defined limitations which will prevent your complicating your application

● Handlebars, the language used by Ember.js allows you to read and understand templates easily. It also helps to load the templates faster.

● Handlebars will ensure to update the template every time you add or remove data.

● Ember.js has an active community that updates the framework regularly and facilitates backward compatibility.

A Comparison Between Ember.js And Vue.js

This article intends to compare the features of both frameworks. Let us see how the characteristics of these frameworks compare. It will help you to make use of the right framework for your web application.

When you need a modern engine for an old application, it is Vue.js which will help you. It combines the best properties of other frameworks. Vue.js is a developing framework. A ready-to-use library of interface elements does not exist. However, many third-party libraries can help you.

Ember.js offers you a well-organized and trustworthy framework. When the development team is big, this is the framework that suits best. It allows everyone to understand the written code and contribute to a common project. The technology will be up-to-date, and the platform will be stable.

Vue.js can help you use the syntax of different kinds. It helps in writing the codes with ease. It is also an SEO friendly framework. Ember is a fully loaded front-end framework and can help you develop the applications very fast. But it is not suitable for developing small projects.

It is not easy to say this is better than that. It will depend on what kind of project you have undertaken. Both have their pluses and minuses. The below table will help in a better comparison.

Final Thoughts

It is not easy to conclude as to which is better. It all depends on the application that you want to develop. Both frameworks are developing. Both are getting updates. Both the communities are working on the frameworks.

While Vue.js is more comfortable for writing codes, Ember is a full-stack framework allowing the development of apps very fast. It is suitable for big projects. It is too complicated to be used for smaller projects.

We hope you had a great time reading this article. If you’ve any questions or suggestions related to this blog, then feel free to ask them in the comment section. Thank You.!