The goal of this post is to show one way to do this division and how to load each file asynchronously, only when the component is requested from a route change. Digital Fortress. Now when you click the button, you will lazy load the GreetComponent inside the parent component. One of the most common examples are components that we usually conditionally hide with v-if directives like modal windows or sidebars. During my daily job I build open source products, interfaces for programmers and engage communities. Part 1 — Introduction to performance optimization and lazy loading. Tạo một component ImageItem. TIP: If you’re using Vue CLI 3 every lazily loaded resource is prefetched by default! To prefetch any resource (usually we prefetch the code-splitted ones like off-screen components or routes) the only thing that you need to do is put it into a tag. Instead of magic comments you can use more general solution like webpack prefetch plugin or workbox. Part 2 — Lazy loading routes and vendor bundle anti-pattern. Lazy Loading Images in VueJS is important to save bandwidth, rank your page better, improve performance considerably and provide a better User Experience, especially if your website has several images . The reason why I’m still writing this article is, that I wanted a more lightweight solution. Now that we know what lazy loading is and why we need it. So what we can do? The answer to this question is trivial and intuitive - everything that is not required on initial render. .lazy. For those still not convinced if it is worth playing with lazy loading, here’s some raw numbers from the simple example we’ve been using. To understand while it’s crucial first we need to understand how Webpack is bundling all of our files. The function representing dynamically imported module returns a Promise that will give us access to the exported members of the module while resolved. Knowing how dynamic imports are working we know that product and category will end up in a separate bundles but what will happen with productGallery module that wasn’t dynamically imported? We can illustrate this process with below image: Now that we know how bundling works, it becomes obvious that the bigger our project gets, the bigger the initial JavaScript bundle becomes. The data changes pretty infrequently, and is only required in certain workflows. Now that you can call yourself master of lazy loaded components! Those components are usually good candidates to be loaded lazily. Let’s assume we have a very small web shop with 4 files: Without digging too much into details let’s see how those files are distributed across the application: In above code, depending on the current route we are dynamically importing either product or category modules and then running init function that is exported by both of them. Lazy loading allows us to split the bundle and serve only the needed parts so users are not wasting time to download and parse code that’ll not be used. nuxt.config.js shows components: true for auto importing components. It’s time to see how we can make use of it in our Vue applications. Versatile. - hilongjw/vue-lazyload v-img lazy loading image. In the next part of this series I’ll show you the most useful (and also the fastest) way to gain some significant performance boost on any Vue.js application. Lazily loaded routes is a popular technique for faster page loading by splitting the build file into many chunks and load it on demand. ... Lazy loading images can significantly improve page performance because it takes the page weight hogged by images and loads them in only when the user actually needs them. Bing is a good example - 2 seconds of delay resulted in a 4.3% loss in revenue per visitor for them. Let’s see another example that will better illustrate this mechanism. The navigator object holds information about the browser. All those saved bytes are still needed for our application to work properly. It’s a graph that links all of our files based on imports. We need a way to tell our application when it should download this chunk of code. As we can see even has a huge room for improvement ;). The purpose of lazy loading is to postpone downloading parts of your application that are not needed by the user on the initial page load which ends up in much better loading time. For instance as a response to a certain user interaction(like route change or click). Now webpack will bundle the content of the dynamically imported module into a separate file. Vue.js - The Progressive JavaScript Framework. By default, v-model syncs the input with the data after each input event (with the exception of IME composition, as stated above). So it turns out that all we need to do to lazily load any component is combining v-if directive and dynamic import statement like this: Lazy loading components can save a lot of time on initial download, but it comes with a price that the user has to pay later. Now the component will be downloaded only when it’s requested. Chúng ta sẽ gọi file này là ImageItem.vue. It would be more efficient if we can split each … Important: Depending on your build configuration prefetching might work only on production mode. Vue Vue.js VueJS. Vue’s async component feature and webpack’s code splitting feature made it easy to lazy-load route components.. To know more about that implementation, you may check my earlier artilce on that here Congratulations! We learned how to use lazy loading with Vue components. In fact, according to Google, 53% of mobile users leave a page that takes longer than three seconds to load. It also makes sense to prefetch lazily loaded routes. The good news is that it’s extremely easy and we can lazily load the entire Single File Component, with it’s CSS and HTML with the same syntax as previously! This is where dynamic imports can help us! Async component is basically an object containing: The second property is a great way to deal with browsers that don’t support prefetching while the third one let us deal with error handling in offline-first application in rare cases when the prefetching fails. If we import a JavaScript module in a standard way like this: It will be added as a node of a main.js in the dependency graph and bundled with it. Lazy Background Images for Vue 2, is a component which can help you load images directly using a URL or loading them dynamically. Ok, we know what lazy loading is and that it’s pretty useful. By making a dynamic import we are basically isolating the given node (in that case Cat) that will be added to the dependency graph and downloading this part when we decide it’s needed (which implies that we are also cutting off modules that are imported inside Cat.js). Vue I18n is internationalization plugin for Vue.js. Prefetching allows us to eliminate bad UX consequence of lazy loading without affecting page performance at all. While bundling our assets Webpack is creating something called If you are using source maps you can click on any file in this list and see which of it’s parts were not invoked. Assuming we have a file called main.js specified as an entry point in our webpack config it will be a root of our dependency graph. This article will outline how to lazy load (dynamically load) VueJS Single File Components. It’s time to see how we can use lazy loading in our own Vue.js applications. A simple lazy-load list component based Vue 2.x, which will be on-demand rendering the list based container element's viewport. Most of the tips in this series will focus on making our JS bundle smaller. A Vue.js plugin for lazyload your Image or Component in your application. Prefetching in simple words, is just downloading certain resources that may be needed in a future before they are requested by the browser. For example if we’re in a Category page of ecommerce shop we could prefetch Product page because there is a high chance user will visit it. Output bundle is just a single (or multiple as we will see in the later parts) javascript file containing all modules from the dependency graph. So they can be consumed in the same way any component is. According to RAIL model guidelines every user input should generate a response in under 100ms.It is almost impossible to achieve such a low response time if we have to download resources before the application is able to respond. Now every js module that we will import in this file will become its node in the graph and every module imported in these nodes will become their nodes. We can easily load some parts of our application lazily with webpack dynamic imports. Laravel + Vue = Love . In most cases, you don’t need all the code from your Javascript bundle immediately when a user visits your website. In our case this might be a lazily loaded modal window. In the previous article, we’ve seen that we can drastically reduce bundle size by lazy loading every route in separation. Objective. Data Fetching; Composition API; Transitions; Scroll Behavior; Lazy Loading Routes. That’s all! Now take a look at this example: Let’s take a quick look at what happened here: Instead of directly importing Cat module we created a function that returns the import() function. Lazy-loading components is a great way to improve the user experience of your app. In other words — loading them only when we really need them. Everything that was imported inside this part will be bundled together so productGallery will end up in the same bundle as product module. Bài viết này tôi sẽ cùng bạn tạo một ví dụ lazy loading Image bằng VueJS. Vue module for lazy-loading images in your vue.js applications. To start with your Vuetify background image app, you can use the VueJS CLI.Go to your development folder, open a terminal and start typing: When building apps with a bundler, the JavaScript bundle can become quite large, and thus affect the page load time. It is wasteful at best, to download, parse and execute the entire bundle everything on every page load when only a few parts are needed. Interesting side note: If you’re using Nuxt.js every in currently opened route will prefetch it’s content automatically. Single-file (.vue) components