It’s time to master another area of Vue performance! By default, v-model syncs the input with the data after each input event (with the exception of IME composition, as stated above). 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). An incrementally adoptable ecosystem that scales between a library and a full-featured framework. Objective. We’ll call this file ImageItem.vue. Technically, both are valid choices - it ultimately depends on the user experience you are aiming for. As we know by making module dynamically imported we are cutting part of the dependency graph. In other words we are just creating some kind of a new entry point for the dependency graph. 17 March 2018. lazyloading A plugin of lazy-load images for Vue2.x. Next is the setI18nLanguage function that will actually change the language in our vueI18n instance, axios and where ever else is needed. If it’s a function the invocation happens only when component is requested to render. Prefetching in simple words, is just downloading certain resources that may be needed in a future before they are requested by the browser. That can result in bad or extremely bad user experience, depending on how long time it takes to download the resource. In our case this might be a lazily loaded modal window. We can then download this optional chunk later, when needed. The answer to this question is trivial and intuitive - everything that is not required on initial render. Now that you can call yourself master of lazy loaded components! A simple lazy-load list component based Vue 2.x, which will be on-demand rendering the list based container element's viewport. Lazy-loading components is a great way to improve the user experience of your app. As the name suggests lazy loading is a process of loading parts (chunks) of your application lazily. Tạo một component ImageItem. Everything that was imported inside this part will be bundled together so productGallery will end up in the same bundle as product module. In the tests that I’ve done, Vue-Lazyload adds about 19 kB to the final bundle size (overall bundle size: 106 kB). Vue I18n is internationalization plugin for Vue.js. So after we’ve downloaded & installed the Element API plugin, we’ll need to create a file called elementapi.php and put it in our craft/config folder. In the first part of this series you read that generally speaking we can assume that any lazily loaded resource is downloaded when it’s import() function is invoked and in case of Vue component that happens only when component is requested to render. Then we are creating a loadedLanguages array that will keep track of our loaded languages. In this article, I'll show you how Vue 3 helps you to do this with new APIs. This is where we’ll define our API: basically, what data are we returning.Our API is incredibly simple, we just want to be able to load the next 9 blog entries. Web developer passionate about newest web technologies with special love for Vue and Progressive Web Apps. - hilongjw/vue-lazyload What problem does this feature solve? Or there might be modals, tooltips and other parts and components that are not needed on every page. The bundle is essentially our entire application’s JavaScript. Bài viết này tôi sẽ cùng bạn tạo một ví dụ lazy loading Image bằng VueJS. This is how I made use of async components in Vue Storefront default theme: TIP: You can display different error message if fetching fails due to a lack of network connectivity by using navigator.onLine property. In other words — loading them only when we really need them. 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. 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. It's a big problem affecting the user experience because the visitors have to wait before accessing the content. In this article, we will explore which types of components can be loaded lazily and, more importantly, how to handle the waiting required for them to download. Even though this technique will give you a massive size reduction there are still plenty of things that we can lazy load to save even more of it. Lazy Background Images for Vue 2, is a component which can help you load images directly using a URL or loading them dynamically. About; Contact; Write for Us! 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: Let’s see another example that will better illustrate this mechanism. In this series, I’ll dig deep into Vue performance optimization techniques that we are using in Vue Storefront and that you can use in your Vue.js applications to make them loading instantly and perform smooth. Eager loading is the default approach of loading JavaScript code on to the DOM, for Vue JS this means using the import statement to bring in a component into the app.vue file. This is where dynamic imports can help us! 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 Interesting side note: When you pass a component to components property of Vue instance under the hood it’s checking if passed value type is object or a function. Now the component will be downloaded only when it’s requested. Congratulations! While bundling our assets Webpack is creating something called Instead of magic comments you can use more general solution like webpack prefetch plugin or workbox. 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. An implication of that behavior is that with v-show component is always downloaded, no matter what’s the value inside it and for v-if directive component is downloaded only after it’s value will become true so remember that you should always use v-if with lazy loaded components! 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 . Webpack’s magic comments are special phrases that are affecting build process when used in a comment. Hãy bắt đầu bằng việc tạo một component hiển thị một hình ảnh (đương nhiên là chưa có lazy load gì cả). All those saved bytes are still needed for our application to work properly. 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. Part 1 — Introduction to performance optimization and lazy loading. In the previous article, we’ve seen that we can drastically reduce bundle size by lazy loading every route in separation. Vue Vue.js VueJS. 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. It’s not so easy when we use webpack that generates names of our bundles depending on order of module resolution (for example entry point becomes main.js, first code-splitted element encountered by webpack becomes 0.js, next one 1.js etc). The function representing dynamically imported module returns a Promise that will give us access to the exported members of the module while resolved. Web developer passionate about newest web technologies with special love for Vue and Progressive Web Apps. As a summary, bigger bundle = fewer users, which can be directly translated to a loss of potential revenue. Interesting side note: If you’re using Nuxt.js every in currently opened route will prefetch it’s content automatically. Fortunately there is a feature that can help us easily prefetch any resource - magic comments. You will learn how to split your Vue code with async routes along with recommended best practices for this process. My goal is to make this series a full and complete guide on Vue apps performance. It’s time to see how we can make use of it in our Vue applications. Support images lazyload in window or build-in element. 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. 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 … Co-founder of Vue Storefront, author of StorefrontUI and Vue.js community partner. 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. When building apps with a bundler, the JavaScript bundle can become quite large, and thus affect the page load time. Versatile. Even though this technique will give you a massive size reduction there are still plenty of things that we can lazy load … For example this code: The component will not be loaded until it is required in the DOM, which is as soon as the v-if value changes to true. It provides a set of values which can be used to configure how the image will display: Values. Thankfully Vue has a very useful feature called async components that solves this problem gracefully. Now we should be able to see how much of the downloaded code was actually used. In this series I’ll dig deep into Vue performance optimization techniques that we are using in Vue Storefront and that you can use in your Vue.js applications to make them loading instantly and perform smooth. Before we get started: there already is a perfectly fine solution for lazy loading images with Vue.js: Vue-Lazyload. It turns out that the solution is extremely simple. This asynchronous behavior is called lazy loading and allows for a smaller initial bundle size. The data changes pretty infrequently, and is only required in certain workflows. There’s still more to learn, but first, we recommend taking a break to play with Vue … Our users will need to download them at some point, which means they have to wait for the postponed resource to be downloaded. Here are the most common ways to invoke dynamic loading of Vue component: Please note that the invocation of lazyComponent function will happen only when component is requested to render in a template. Most of the tips in this series will focus on making our JS bundle smaller. v2-lazy-list. Fetching Before Navigation : Fetch data before navigation in the route enter guard, and perform the navigation after data has been fetched. Vue module for lazy-loading images in your vue.js applications. During my daily job I build open source products, interfaces for programmers and engage communities. Continuing my dive into the Intersection Observer API, this week I look at probably the most practical use case for them, lazy loading images! Lazy Loading Images in VueJs. // src/utils/lazy-load-component.js export default function lazyLoadComponent ({ componentFactory , loading , loadingData , }) { let resolveComponent ; return () => ({ // We return a promise to resolve a // component eventually. One of the most common examples are components that we usually conditionally hide with v-if directives like modal windows or sidebars. When building apps with a bundler, the JavaScript bundle can become quite large, and thus affect the page load time. It also makes sense to prefetch lazily loaded routes. …that’s all you need! TIP: If you’re using Vue CLI 3 every lazily loaded resource is prefetched by default! Simply put this comment inside dynamic import function like in the example below and your resource will be prefetched: At the moment of code execution webpack will look for every magic comment like this and dynamically (which means at the code execution time, not in a build time) add tag to section of your application: Now when user will request chunk with ModalWindow.vue it will already be in a memory and appear instantly. In the next part we will learn when it’s wise to lazy load third party libraries, how to identify which one of them are too big and how to easily find smaller equivalents. Learn more in the Directory Structure book in the Components chapter. My goal is to make this series a full and complete guide on Vue apps performance. 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. You can add the lazy modifier to instead sync after change events: < input v-model.lazy = "msg" >.number In this article we digged really deep into lazy loading of individual components. 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. Especially lack of the Safari support can be painful. One of such magic comments is /* webpackPrefetch: true */. 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. That’s probably the easiest way to gain some performance boost. Take a look at below example: Assuming isModalVisible variable is set to false even though both statements will take the same effect from the user point of view the v-if directive will remove component from the DOM completely while v-show will just add display: none CSS property. The navigator object holds information about the browser. Angular allows us to pass data to @Input() decorated properties and handle events of lazy-loaded components using the instance property of the lazy-loaded component. As we can see even vuejs.org has a huge room for improvement ;). In most cases, you don’t need all the code from your Javascript bundle immediately when a user visits your website. In the previous article, we’ve seen that we can drastically reduce bundle size by lazy loading every route in separation. Bundling this module with our initial bundle is a bad idea since it is not needed at all times. Chúng ta sẽ gọi file này là ImageItem.vue. Co-founder of Vue Storefront, author of StorefrontUI and Vue.js community partner. December 14, 2018 / Javascript, Tutorial / Niket Pathak / 3 min read . The answer is easy — lazy loading and code splitting. Prefetching seems to solve all of our problems but browser support for this feature is not there yet for some of them. Grouping Components in the Same Chunk ; Navigation Failures # Lazy Loading Routes. So they can be consumed in the same way any component is. If nothing happens when we interact with a website, we either perceive the application as slow or broken, and most of us leave the site. We need a way to tell our application when it should download this chunk of code. Prefetching does not affect your page load or how fast your app becomes interactive (TTI). Async components are also wrapped in a function, like dynamic imports are. This example will be using Axios and MomentJS for data fetching and date formatting, respectively. It’s important to note that the prefetching will only start after the browser has finished the initial load and becomes idle. During my daily job I build open source products, interfaces for programmers and engage communities. Lazy loading Vue components. It’s time to see how we can use lazy loading in our own Vue.js applications. Now that we know what lazy loading is and why we need it. Prefetching allows us to eliminate bad UX consequence of lazy loading without affecting page performance at all. We learned how to use lazy loading with Vue components. Project Creation Lazily loaded routes is a popular technique for faster page loading by splitting the build file into many chunks and load it on demand. On the other hand, lazy loading refers to an approach where all of the scripts are not loaded on the DOM as the application starts, instead, they are only loaded when requested, making the JavaScript bundle size very small at … That’s all! This usually means everything that the user doesn’t see until he/she interacts with our app in some way. A simple lazy-load list component based Vue 2.x, which will be on-demand rendering the list based container element's viewport. Code splitting is just a process of splitting the app into this lazily loaded chunks. So how we can cut off bundle size when we still need to add new features and improve our application? I have a problem that, in the architecture of my apps, I want to load all the components of my application asynchronally. It is important to understand exactly when a code-splitted component is fetched. For instance as a response to a certain user interaction(like route change or click). Let’s dig a little bit deeper. Part 1 — Introduction to performance optimization and lazy loading. dependency graph (click here to see how it looks like). Important: Depending on your build configuration prefetching might work only on production mode. Digital Fortress. This series is based on learnings from Vue Storefront performance optimization process. 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? To see how much of the JavaScript code is actually used in our website we can go to the devtools -> cmd+shift+p -> type coverage -> hit ‘record’. v-img lazy loading image. 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. Part 2 — Lazy loading routes and vendor bundle anti-pattern. Now webpack will bundle the content of the dynamically imported module into a separate file. We will walk you through some techniques to lazy loading images that can improve user experience and increase the number of your web visitors. $ vue init webpack-simple infinite-scroll-vuejs Getting Initial User Data. Grouping Components in the Same Chunk; Extending RouterLink; Navigation Failures; Dynamic Routing; Migrating from Vue 2 # Lazy Loading Routes. So what we can do? We can easily load some parts of our application lazily with webpack dynamic imports. Webpack is using this dependency graph to detect which files it should include in the output bundle. Laravel + Vue = Love . The reason why I’m still writing this article is, that I wanted a more lightweight solution. While mobile-first approach becomes a standard and uncertain network conditions are something we should always take into consideration it’s harder and harder to keep your application loading fast. Let’s see how they work and how they differ from regular imports. A small size Vue.js directive for lazy loading images using IntersectionObserver API - mazipan/vue-tiny-lazyload-img Link Making an API. To understand while it’s crucial first we need to understand how Webpack is bundling all of our files. In short we are creating a new VueI18n instance as we normally would. image-source - The source of the desired image (required) loading-image - Path to the loader image (png, svg etc) (required) The easiest way to lazy load your content - 1.0.1 - a JavaScript package on npm - Libraries.io Display a loading state while data is being fetched. Single-file (.vue) components