How to reasonably use keep-alive for component optimization in vue

How to reasonably use keep-alive for component optimization in Vue

Introduction:
In Vue development, we often encounter situations where we need to reuse components, such as tab switching or routing jumps Keep component status from being lost. The keep-alive in Vue was born to deal with this need for reusable components. This article will introduce how to reasonably use keep-alive in Vue to optimize components to achieve better performance and user experience.

1. What is keep-alive
In Vue, keep-alive is an abstract component built into Vue, which is used to cache dynamic components or improve the state retention of components. It temporarily caches inactive components instead of destroying them, thus preserving their state and avoiding re-rendering when switching back.

2. Use keep-alive to optimize components

1. Use include and exclude attributes for fine control
   The keep-alive component can precisely control which components by setting include and exclude attributes. Caching is required and which components do not need to be cached. The include attribute accepts a string or regular expression, and only components with matching names will be cached; while the exclude attribute is the opposite of include, and only components that do not match will be cached. By using these two properties together, we can control the keep-alive cache component more finely.

<template>
  <div>
    <keep-alive :include="includeList" :exclude="excludeList">
      <router-view></router-view>
    </keep-alive>
  </div>
</template>

<script>
export default {
  data() {
    return {
      includeList: [/ComponentA/, /ComponentB/],
      excludeList: [/ComponentC/],
    };
  },
};
</script>

2. Use the max attribute to control the maximum number of caches
   The keep-alive component also provides the max attribute to control the maximum number of cached components. When the value set by max is exceeded, the earliest component that enters the cache will be destroyed and the memory will be released. By setting the max attribute appropriately, a balance can be struck between performance and memory.

<template>
  <div>
    <keep-alive max="10">
      <router-view></router-view>
    </keep-alive>
  </div>
</template>

3. Use life cycle hooks to maintain state
   After the component is cached, it will call the corresponding life cycle hook function, which provides convenience for us to maintain state. Among them, the activated hook is called when the component is activated and inserted into the DOM, and the deactivated hook is called when the component is cached. By using these two life cycle hook functions, we can save some state that needs to be maintained when the component is activated, and clean up some state that does not need to be maintained when the component is cached.

<template>
  <div>
    <keep-alive>
      <router-view v-slot="{ Component }">
        <component
          :is="Component"
          v-bind="$route.params"
          @hook:activated="onActivated"
          @hook:deactivated="onDeactivated"
        ></component>
      </router-view>
    </keep-alive>
  </div>
</template>

<script>
export default {
  methods: {
    onActivated() {
      // 在组件被激活时进行一些操作，比如发送请求、更新数据等
    },
    onDeactivated() {
      // 在组件被缓存时进行一些清理工作，比如重置状态、清除定时器等
    },
  },
};
</script>

Conclusion:
By using keep-alive properly, we can optimize the performance and user experience of Vue applications. By finely controlling cache components, setting the maximum number of caches, and utilizing lifecycle hook functions, we can improve the response speed of the application, reduce unnecessary data requests, and maintain the continuity of component state. I hope this article will help you use keep-alive for component optimization in Vue applications.

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