vuejs lazy load data

Interesting side note: If you’re using Nuxt.js every in currently opened route will prefetch it’s content automatically. An incrementally adoptable ecosystem that scales between a library and a full-featured framework. …that’s all you need! Chúng ta sẽ gọi file này là ImageItem.vue. 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: This series is based on learnings from Vue Storefront performance optimization process. Fortunately there is a feature that can help us easily prefetch any resource - magic comments. This example will be using Axios and MomentJS for data fetching and date formatting, respectively. 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. The easiest way to lazy load your content - 1.0.1 - a JavaScript package on npm - Libraries.io During my daily job I build open source products, interfaces for programmers and engage communities. But what if we need our Cat module only under certain circumstances like a response to a user interaction? One of the most common examples are components that we usually conditionally hide with v-if directives like modal windows or sidebars. This asynchronous behavior is called lazy loading and allows for a smaller initial bundle size. 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. In most cases, you don’t need all the code from your Javascript bundle immediately when a user visits your website. Co-founder of Vue Storefront, author of StorefrontUI and Vue.js community partner. In other words we are just creating some kind of a new entry point for the dependency graph. Part 1 — Introduction to performance optimization and lazy loading. Next: Optimizing third-party libraries (4 of 6), Previous: Vue.js Router Performance (2 of 6). By using below techniques we were able to cut off size of our initial bundle by 70% and made it load in a blink of an eye. Display a loading state while data is being fetched. 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. 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). Web developer passionate about newest web technologies with special love for Vue and Progressive Web Apps. 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. By default, v-model syncs the input with the data after each input event (with the exception of IME composition, as stated above). Learn more in the Directory Structure book in the Components chapter. Web developer passionate about newest web technologies with special love for Vue and Progressive Web Apps. It's a big problem affecting the user experience because the visitors have to wait before accessing the content. It’s a graph that links all of our files based on imports. Continuing my dive into the Intersection Observer API, this week I look at probably the most practical use case for them, lazy loading images! 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. Code splitting is just a process of splitting the app into this lazily loaded chunks. 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. 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. If it’s a function the invocation happens only when component is requested to render. Vue I18n is internationalization plugin for Vue.js. 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. While bundling our assets Webpack is creating something called Vue Vue.js VueJS. December 14, 2018 / Javascript, Tutorial / Niket Pathak / 3 min read . 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 … In this tutorial, we will show you some techniques of lazy load images using JavaScript. So what we can do? For instance as a response to a certain user interaction(like route change or click). It’s important to note that the prefetching will only start after the browser has finished the initial load and becomes idle. We learned how to use lazy loading with Vue components. I have a problem that, in the architecture of my apps, I want to load all the components of my application asynchronally. 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. This is why the trick with v-if works. In the previous article, we’ve seen that we can drastically reduce bundle size by lazy loading every route in separation. Ok, we know what lazy loading is and that it’s pretty useful. Passing Data to Lazy-Loaded Component. Next is the setI18nLanguage function that will actually change the language in our vueI18n instance, axios and where ever else is needed. Even though our users will need to download lazily loaded chunks at some point, which means they have to wait for the postponed resources to be downloaded we can download them before they’re requested with prefetching and in case it’s not supported by our browsers we can still deliver great waiting experience with async components. 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. // 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. 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. How cool is this? For example, we don’t need to spend valuable resources on loading the “My Page” area for guests that visits our website for the first time. There are various npm packages for infinite scroll that you can use for your Vue app, but some of these may be overkill. 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 … Let’s dig a little bit deeper. Prefetching allows us to eliminate bad UX consequence of lazy loading without affecting page performance at all. Co-founder of Vue Storefront, author of StorefrontUI and Vue.js community partner. dependency graph (click here to see how it looks like). Lazy loading Vue components. The reason why I’m still writing this article is, that I wanted a more lightweight solution. Data Fetching; Scroll Behavior; Lazy Loading Routes. It is important to understand exactly when a code-splitted component is fetched. Hãy bắt đầu bằng việc tạo một component hiển thị một hình ảnh (đương nhiên là chưa có lazy load gì cả). It’s time to see how we can make use of it in our Vue applications. Congratulations! That can result in bad or extremely bad user experience, depending on how long time it takes to download the resource. Prefetching does not affect your page load or how fast your app becomes interactive (TTI). Learn how to lazy load routes with a free lesson on Vue School. 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. 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 bundle is essentially our entire application’s JavaScript. 17 March 2018. lazyloading A plugin of lazy-load images for Vue2.x. In this article we digged really deep into lazy loading of individual components. TIP: If you’re using Vue CLI 3 every lazily loaded resource is prefetched by default! 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? Let’s see how they work and how they differ from regular imports. Let’s see another example that will better illustrate this mechanism. Now webpack will bundle the content of the dynamically imported module into a separate file. Async components are also wrapped in a function, like dynamic imports are. 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. Prefetching in simple words, is just downloading certain resources that may be needed in a future before they are requested by the browser. A simple lazy-load list component based Vue 2.x, which will be on-demand rendering the list based container element's viewport. Technically, both are valid choices - it ultimately depends on the user experience you are aiming for. $ vue init webpack-simple infinite-scroll-vuejs Getting Initial User Data. 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. nuxt.config.js shows components: true for auto importing components. As we can see even vuejs.org has a huge room for improvement ;). Objective. Now that we know what lazy loading is and why we need it. 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. 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 When we click a button, we expect a reaction immediately. Our users will need to download them at some point, which means they have to wait for the postponed resource to be downloaded. It’s time to see how we can make use of it in our Vue applications. 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’. During my daily job I build open source products, interfaces for programmers and engage communities. When building apps with a bundler, the JavaScript bundle can become quite large, and thus affect the page load time. 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. A small size Vue.js directive for lazy loading images using IntersectionObserver API - mazipan/vue-tiny-lazyload-img 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. 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. That’s all! 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. Grouping Components in the Same Chunk ; Navigation Failures # Lazy Loading Routes. Now when you click the button, you will lazy load the GreetComponent inside the parent component. We’ll call this file ImageItem.vue. Those components are usually good candidates to be loaded lazily. Most of the tips in this series will focus on making our JS bundle smaller. Important: Depending on your build configuration prefetching might work only on production mode. In the tests that I’ve done, Vue-Lazyload adds about 19 kB to the final bundle size (overall bundle size: 106 kB). So how we can cut off bundle size when we still need to add new features and improve our application? Vue module for lazy-loading images in your vue.js applications. image-source - The source of the desired image (required) loading-image - Path to the loader image (png, svg etc) (required) Now that we know what lazy loading is and why we need it. The answer is easy — lazy loading and code splitting. As the name suggests lazy loading is a process of loading parts (chunks) of your application lazily. The longer a user has to wait, the more likely he is to leave our site. Such delay is much worse for components than whole pages because we’re not used to wait for individual parts of the UI to appear. Single-file (.vue) components