UniApp implements optimization strategies for subcontracted loading and lazy page loading

UniApp is a cross-platform development framework based on Vue.js. It can run on multiple platforms at the same time, such as WeChat applet, H5, App, etc. In actual development, as the application scale increases, pages and resources also increase accordingly. In order to improve application performance and user experience, we can adopt optimization strategies of subcontracted loading and lazy page loading.

1. Sub-package loading

Sub-package loading in UniApp refers to separating some pages and resources of the application to reduce the package size when loading for the first time and improve the first loading speed. In UniApp, subpackage loading can be achieved through subpackage pre-download and dynamic subpackage.

1. Sub-package pre-download

Sub-package pre-download refers to pre-downloading the sub-package content during application initialization to improve the loading speed when users click on the sub-package page. In the manifest.json file of uni-app, we can configure the subpackage path that needs to be pre-downloaded. The code example is as follows:

{
  "preloadRule": {
    "packages": [
      {
        "root": "pages/subPackage1",
        "name": "subPackage1"
      },
      {
        "root": "pages/subPackage2",
        "name": "subPackage2"
      }
    ]
  }
}

In the above example, we configured two subpackages subPackage1 and subPackage2, and set their root paths and names. When the application is initialized, UniApp will automatically pre-download the contents of these two sub-packages so that the page can be loaded quickly when the user clicks on it.

2. Dynamic subcontracting

Dynamic subcontracting refers to dynamically loading the required subcontracting according to user needs during the application running process. Through dynamic sub-packaging, you can avoid loading too many pages and resources at once. In UniApp, you can use the uni.requireSubpackage() method to implement dynamic subpackaging. The sample code is as follows:

uni.requireSubpackage({
  root: 'pages/subPackage1',
  success: function(res) {
    // 分包加载成功时的回调函数
    console.log('分包加载成功');
  },
  fail: function(res) {
    // 分包加载失败时的回调函数
    console.log('分包加载失败');
  }
});

In the above example, we use the uni.requireSubpackage() method to load the subPackage1 subpackage. When the sub-package is loaded successfully, the success callback function will be executed; when the sub-package loading fails, the fail callback function will be executed.

2. Page lazy loading

Lazy loading of pages in UniApp means that only the basic structure and necessary resources of the page are loaded before the page is displayed for the first time, and other non-essential resources are loaded after the page is displayed. to load. Through lazy loading of pages, resource requests during the first load can be reduced and the page loading speed can be improved.

To implement lazy loading of pages, we need to use the uni.lazyLoadComponent() method. This method can delay the loading of the component until it is actually used. The sample code is as follows:

<template>
  <view>
    <lazy-component v-if="showLazyComponent" />
  </view>
</template>

<script>
export default {
  data() {
    return {
      showLazyComponent: false
    };
  },
  mounted() {
    setTimeout(() => {
      this.showLazyComponent = true;
    }, 2000);
  }
};
</script>

In the above example, the lazy-component component will be loaded and displayed only when showLazyComponent is true. By setting a delay function, you can load the component before it is actually used.

3. Summary

Through the optimization strategy of subcontracted loading and lazy page loading, the performance and user experience of UniApp applications can be effectively improved. By rationally dividing subcontracting and lazy loading of page components, resource requests during first loading can be reduced and the loading speed of the application can be improved. Developers can choose appropriate optimization strategies for implementation based on the specific circumstances and needs of the application. The above code examples can be used as a reference to help developers better implement sub-package loading and lazy page loading.

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