How to handle image caching and preloading in Vue?

How to handle image caching and preloading in Vue?

When developing Vue projects, we often need to deal with caching and preloading of images to improve website performance and user experience. This article will introduce some methods of handling image caching and preloading in Vue, and give corresponding code examples.

1. Image caching

1. Use image lazy loading (Lazy Loading)

Image lazy loading is a technology that delays loading of images, that is, in The image is loaded when the page scrolls to the location of the image. This reduces requests for image resources when the page is first loaded. Commonly used plug-ins for Vue include vue-lazyload and vue-lazy-component.

Install vue-lazyload plug-in:

npm install vue-lazyload --save

Introduce and use in main.js:

import Vue from 'vue'
import VueLazyload from 'vue-lazyload'

Vue.use(VueLazyload)

Use in components:

<template>
  <img  src="/static/imghw/default1.png"  data-src="image"  class="lazy"  v-lazy="imageUrl" alt="How to handle image caching and preloading in Vue?" >
</template>

<script>
export default {
  data() {
    return {
      imageUrl: require('@/assets/image.jpg')
    }
  }
}
</script>

2. Use CDN

to deploy commonly used static resources (such as images) to CDN. The resources can be cached on CDN nodes, reducing requests to the source site and improving image loading speed.

In the configuration file of the Vue project, you can configure the CDN URL to the baseUrl of the static resource:

// vue.config.js
module.exports = {
  publicPath: process.env.NODE_ENV === 'production'
    ? 'https://cdn.example.com'
    : '/'
}

2. Image preloading

Image preloading means Load image resources in advance when the page loads to reduce the loading time when users visit. In Vue, you can use technologies such as Dynamic Import and Intersection Observer to implement image preloading.

1. Use dynamic import

In components that need to be preloaded, use dynamic import to load image resources:

export default {
  data() {
    return {
      image: null
    }
  },
  beforeMount() {
    import('@/assets/image.jpg').then((src) => {
      this.image = src.default
    })
  }
}

Use in templates:

<template>
  <img src="/static/imghw/default1.png"  data-src="image"  class="lazy"  v-if="image" : alt="">
</template>

2. Use Intersection Observer

Intersection Observer is an API that listens for elements entering or leaving the window. It can be used to determine whether the image is within the visible area, thereby realizing the image Preloading.

Use Intersection Observer in the component to monitor images:

<template>
  <img src="/static/imghw/default1.png"  data-src="imageUrl"  class="lazy"  ref="image" : alt="">
</template>

<script>
export default {
  data() {
    return {
      imageUrl: require('@/assets/image.jpg')
    }
  },
  mounted() {
    const observer = new IntersectionObserver((entries) => {
      if (entries[0].isIntersecting) {
        this.imageUrl = require('@/assets/image.jpg')
        observer.disconnect()
      }
    })

    observer.observe(this.$refs.image)
  }
}
</script>

The above is how to handle image caching and preloading in Vue. By rationally using image lazy loading and preloading, the loading speed and user experience of the website can be improved. Hope this article can be helpful to you.

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