How the keep-alive component implements page caching in vue

How the keep-alive component implements page caching in Vue

Introduction:
When developing Vue applications, we often encounter situations where we need to cache certain pages. In order to improve user experience and application performance, we can use the keep-alive component in Vue to implement page caching. This article will introduce the basic usage of the keep-alive component and provide some code examples.

1. The concept and function of the keep-alive component
keep-alive is an abstract component officially provided by Vue, which is used to cache dynamic components or router-view instances. This component maintains a cache queue inside Vue. When the component is switched or destroyed, the corresponding component instance will be saved in the memory so that the instance can be obtained directly from the memory the next time it is re-rendered, avoiding re-creation and destruction, and improving Page loading speed and user experience.

2. Basic usage of keep-alive components
Using keep-alive components in Vue is very simple. Just wrap the components that need to be cached with the tag.

<template>
  <div>
    <keep-alive>
      <router-view></router-view>
    </keep-alive>
  </div>
</template>

In the above example, the component is a routing component provided by Vue Router, which can be used to dynamically render different components based on the current URL path. In this example, is wrapped by the tag, indicating that the component needs to be cached.

3. Characteristics of keep-alive components

1. include and exclude attributes
   Through the include and exclude attributes, we can control which components need to be cached, and which Components do not need to be cached.

   <template>
     <div>
       <keep-alive :include="includeComponents" :exclude="excludeComponents">
         <router-view></router-view>
       </keep-alive>
     </div>
   </template>
   
   <script>
     export default {
       data() {
         return {
           includeComponents: ['ComponentA', 'ComponentB'],
           excludeComponents: ['ComponentC']
         }
       }
     }
   </script>

   In the above example, the include attribute specifies the list of components that need to be cached, and the exclude attribute specifies the list of components that do not need to be cached. Use this to flexibly control the behavior of page caching.

2. max attribute
   The max attribute is used to limit the number of cached components. When the cached components exceed the limit, the old components will be destroyed. The default value of this attribute is 0, which means no limit.

   <template>
     <div>
       <keep-alive :max="3">
         <router-view></router-view>
       </keep-alive>
     </div>
   </template>

   In the above example, only up to 3 component instances are cached, and components exceeding the limit will be destroyed.

   4. Summary
   By using the keep-alive component, we can easily implement page caching in Vue applications. It can reduce the creation and destruction of components and improve application performance and user experience. In addition to basic usage, we can further control the behavior of page caching through attributes such as include, exclude, and max. I hope the code examples and instructions in this article can help you better understand and apply the keep-alive component.

   Reference link:

   • Vue official documentation: https://vuejs.org/v2/api/#keep-alive
   • Vue Router official documentation: https ://router.vuejs.org/

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