How to reduce repeated rendering of pages through Vue's keep-alive component

How to reduce repeated rendering of pages through Vue's keep-alive component

In Vue.js, repeated rendering of pages is a common problem. When we switch pages or jump between multiple components, Vue will re-render the entire component tree, and this process may consume a lot of computing resources and time. To solve this problem, Vue provides a built-in component called keep-alive, which can help us reduce repeated rendering of the page.

The keep-alive component is an abstract component provided by Vue for caching stateful sub-components. Its function is to cache sub-components to prevent them from being destroyed and re-created, thereby reducing the cost of repeated rendering of the page. Let's take a look at how to use the keep-alive component to optimize page performance.

First, we need to use the keep-alive component in the parent component to wrap the child components that need to be cached. For example, we have a subcomponent called Home that we want to cache when switching pages. We can wrap it in a keep-alive component, as shown below:

<template>
  <keep-alive>
    <Home />
  </keep-alive>
</template>

Next, we can further optimize the rendering of the page by setting the properties of the keep-alive component. The keep-alive component provides include and exclude attributes to specify which components need to be cached and which components do not need to be cached.

For example, if we want to cache all sub-components, we can set the include attribute to "*":

<template>
  <keep-alive :include="['*']">
    ...
  </keep-alive>
</template>

If we only want to cache specific sub-components, we can include The attribute is set to an array containing the names of subcomponents that need to be cached:

<template>
  <keep-alive :include="['Home', 'About']">
    ...
  </keep-alive>
</template>

In addition to the include attribute, the keep-alive component also provides the exclude attribute, which is used to specify which components do not need to be cached. Similar to the include attribute, the exclude attribute can be set to "*" to exclude all components, or to an array containing the names of subcomponents that do not need to be cached.

While using the keep-alive component, we can also use the hook function it provides to further optimize the rendering of the page. The keep-alive component has two hook functions: activated and deactivated. The activated hook function is called when the component is activated, while the deactivated hook function is called when the component is deactivated.

We can perform some logic in the activated hook function that needs to be executed when the subcomponent is activated by the cache. For example, you can send a network request in the activated hook function to update the data of the subcomponent. Similarly, in the deactivated hook function, you can perform some logic that needs to be executed when the subcomponent is deactivated, such as clearing cached data, etc.

The following is an example of using the activated hook function:

<template>
  <keep-alive :include="['Home']">
    <Home />
  </keep-alive>
</template>

<script>
export default {
  components: {
    Home
  },
  activated() {
    // 在子组件被激活时执行的逻辑
    this.$http.get('/api/data')
      .then(response => {
        this.data = response.data;
      })
      .catch(error => {
        console.log(error);
      });
  }
}
</script>

By using the keep-alive component, we can effectively reduce the repeated rendering of the page and improve the performance and user experience of the page. At the same time, we can also use include and exclude attributes, hook functions and other functions to further optimize the rendering of the page. I hope this article will help you understand and use Vue's keep-alive component.

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