How to deal with the lazy loading problem of images encountered in Vue development

How to deal with the lazy loading problem of images encountered in Vue development

With the continuous development of technology, front-end frameworks are becoming more and more diverse and powerful. As one of the popular front-end frameworks, Vue is widely used in the development of various web applications. In Vue development, lazy loading of images is a common requirement. Especially when there are a large number of images in the web page, lazy loading can effectively improve page loading speed and user experience. This article will introduce how to deal with the lazy loading problem of images encountered in Vue development.

1. What is lazy loading of images

Lazy loading of images, also known as delayed loading, means that when the page is loaded, only images within the current viewport range are loaded. , when the user scrolls the page or the viewport changes, pictures in other visible areas are dynamically loaded. Through lazy loading of images, you can avoid the problem of slow page loading caused by requesting a large number of images at one time, and improve page loading speed and user experience.

2. How to implement lazy loading of images in Vue

You can implement lazy loading of images in Vue through the following methods:

1. Use a third-party library: Vue-Lazyload It is a lightweight Vue image lazy loading plug-in that is mature, stable, and easy to configure and use. Just follow the documentation instructions, install the plug-in and configure it to achieve lazy loading of images. The following is a basic usage example of Vue-Lazyload:

Install the plug-in: npm install vue-lazyload --save

Import in the entry file of the Vue project (such as main.js) And configure the plug-in:

import VueLazyload from 'vue-lazyload'
Vue.use(VueLazyload, {
loading: require('Loading placeholder map path'),
error : require('Placemap path that failed to load'),
})

Use lazy loading images in components:

2. Custom instructions: In addition to using third-party libraries, we can also use custom instructions To achieve lazy loading of images. The following is the implementation of a simple custom directive:

Create a directive folder in the Vue project and create the lazyload.js file:

// lazyload.js
function isInViewport(el) {
const rect = el.getBoundingClientRect();
return (

rect.top >= 0 &&
rect.bottom <= (window.innerHeight || document.documentElement.clientHeight)

);
}

function loadImage(el) {
if (el.src !== el.getAttribute('data-src')) {

el.src = el.getAttribute('data-src'); // 加载图片

}
}

export default {
inserted: function(el ) {

el.setAttribute('data-src', el.src); // 将原始src属性保存到data-src属性中
el.classList.add('lazy'); // 添加样式类
if (isInViewport(el)) {
  loadImage(el);
}

},
bind: function(el) {

if (!el.getAttribute('data-src')) {
  el.setAttribute('data-src', el.src);
  el.src = require('加载中的占位图路径');
}

},
update: function(el) {

if (isInViewport(el)) {
  loadImage(el);
}

}
}

Introduce custom instructions into components that require lazy loading:

By customizing instructions, we can make more customizations and extensions according to needs.

3. Notes

When using Vue for lazy loading of images, you need to pay attention to the following issues:

1. Image path processing: When using lazy loading, You need to save the path of the image to the corresponding attribute, and then assign the path to the src attribute when the image needs to be loaded. When using Vue's import or require syntax to introduce images, pay attention to path processing to ensure that the image path is correct.
2. Placeholder image settings: In order to improve user experience, you can use placeholder images to display alternative content during the image loading process. In Vue-Lazyload, you can set the placeholder image and the replacement image after loading failure by configuring the loading and error options. The custom instruction method requires setting the placeholder image through code in the instruction.
3. Performance considerations: Lazy loading of images can improve the loading speed of the page, but you must also pay attention to the implementation of lazy loading not to excessively consume performance. When there are a large number of images on the page, it may lead to excessive event monitoring and DOM operations, thereby affecting page performance. Therefore, in actual use, testing and optimization need to be carried out according to specific conditions to achieve the best performance.

Conclusion:

Lazy loading of images is one of the commonly used technologies in front-end development, and it also needs to be used in Vue development. Whether you use a third-party library or a custom instruction, you can implement the image lazy loading function very well. By properly using lazy loading, you can improve page performance and user experience, and reduce unnecessary resource consumption. I hope this article will help you deal with the problem of lazy loading of images in Vue development.

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