How to use keep-alive in vue to improve front-end development efficiency

How to use keep-alive in Vue to improve front-end development efficiency

The performance of front-end development has always been one of the focuses of developers. In order to improve user experience and page loading speed, we often have to consider how to optimize front-end rendering. As a popular front-end framework, Vue provides keep-alive components to solve the performance problems of inactive components. This article will introduce the use of keep-alive and show how it can improve front-end development efficiency in Vue through code examples.

1. The role and principle of keep-alive

In Vue, the destruction and re-creation of components is a time-consuming process. If we have some inactive components that are not used frequently between switches or page views, but are recreated every time we switch, it will lead to performance degradation. The keep-alive component can cache instances of these inactive components, thereby avoiding unnecessary destruction and re-creation and improving rendering performance.

In principle, keep-alive caches the virtual DOM of inactive components in memory and directly restores the cached instance when the component switches without re-creating it. This can reduce the time and overhead of page rendering, thereby improving the efficiency of front-end development.

2. Using keep-alive

Using keep-alive in Vue is very simple, just wrap the component you want to cache outside the component. Here is an example:

<template>
  <div>
    <h1>首页</h1>
    <keep-alive>
      <router-view></router-view>
    </keep-alive>
  </div>
</template>

<script>
export default {
  name: 'App',
}
</script>

In the above code, we used the <keep-alive> tag outside the <router-view> tag, which means We will cache instances of <router-view>.

3. Keep-alive properties

In addition to the basic usage methods, keep-alive also provides some properties that can more flexibly control cached components.

• include: Used to specify the name of the component to be cached, supporting strings or regular expressions. For example, include="Home,About" means that only components named "Home" and "About" will be cached.
• exclude: Used to specify component names that do not need to be cached. It also supports strings or regular expressions. For example, exclude="Login,Register" means that components named "Login" and "Register" are not cached.
• max: Used to specify the maximum number of components to be cached. When the number of cached components exceeds the limit, the oldest cached component will be destroyed. For example, max="10" means that the maximum cache is 10 components.

Here is an example that demonstrates how to use the include and exclude attributes:

<template>
  <div>
    <h1>首页</h1>
    <keep-alive :include="['Home', 'About']" :exclude="['Login', 'Register']">
      <router-view></router-view>
    </keep-alive>
  </div>
</template>

<script>
export default {
  name: 'App',
}
</script>

4. keep-alive life cycle

keep-alive itself also has life cycle hook functions, which can be used to monitor the status changes of cache components. The main life cycle hook functions are:

• activated: called when the cache component is activated, usually triggered when the component enters the cache for the first time or is restored from the cache.
• deactivated: Called when the cache component is deactivated, usually triggered when the component leaves the cache or is destroyed from the cache.

Here is an example showing how to use the activated and deactivated hook functions:

<template>
  <div>
    <h1>首页</h1>
    <keep-alive :include="['Home', 'About']" @activated="onActivated" @deactivated="onDeactivated">
      <router-view></router-view>
    </keep-alive>
  </div>
</template>

<script>
export default {
  name: 'App',
  methods: {
    onActivated() {
      console.log('组件被激活')
    },
    onDeactivated() {
      console.log('组件被停用')
    },
  },
}
</script>

By listening to these life cycle hook functions, We can handle some specific events, such as performing certain actions when the cache component is reactivated.

Summary:

Using keep-alive components is an effective way to optimize Vue application performance. By caching instances of inactive components, we can avoid unnecessary destruction and re-creation, thereby improving front-end development efficiency. Reasonable use of keep-alive in the application, combined with related attributes and life cycle hook functions, can better optimize page rendering and user experience.

I hope this article can help everyone understand and use keep-alive in Vue.

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