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

Vue.js is a popular front-end framework that uses component development to allow us to better manage and reuse code. Among them, the keep-alive component is a very practical function provided by Vue.js, which can help us optimize page performance. In this article, we will discuss how to properly use keep-alive for component caching.

What is the keep-alive component?

In Vue.js, keep-alive is an abstract component that can be wrapped around dynamic components to achieve the effect of component caching. When the component wrapped in it is switched, keep-alive will cache it instead of destroying it, so that the next time you switch to the component again, there is no need to re-render and initialize it, thus improving the response of the page. Speed ​​and user experience.

How to use the keep-alive component?

Using the keep-alive component is very simple, just wrap the component that needs to be cached in the <keep-alive> tag. Here is an example:

<template>
  <div>
    <keep-alive>
      <component :is="currentComponent"></component>
    </keep-alive>

    <button @click="switchComponent">切换组件</button>
  </div>
</template>

<script>
export default {
  data() {
    return {
      currentComponent: 'ComponentA',
    };
  },
  methods: {
    switchComponent() {
      this.currentComponent = this.currentComponent === 'ComponentA' ? 'ComponentB' : 'ComponentA';
    },
  },
};
</script>

In the above example, we have created a parent component that contains two dynamic components. When the button is clicked, switches the display between two dynamic components. We wrap these two dynamic components in keep-alive to implement component caching.

Notes

When using the keep-alive component, there are some precautions that we need to pay attention to:

Use include and exclude properties

keep-alive provides include and exclude properties for specifying components that need to be cached and components that need to be excluded from cache. Both properties can accept a string or an array of regular expressions.

<keep-alive :include="['ComponentA', /^ComponentB/]" :exclude="['ComponentB']">
  <component :is="currentComponent"></component>
</keep-alive>

In the above example, we specified the ComponentA components that need to be cached and the components that match the ComponentB regular expression, and excluded ComponentB components.

Use the max attribute

keep-alive also provides the max attribute to specify the component instance that needs to be cached Quantity limit. When the number of cached component instances reaches the upper limit, the oldest cached component instance will be destroyed.

<keep-alive :max="5">
  <component :is="currentComponent"></component>
</keep-alive>

In the example above, we limited caching to a maximum of 5 component instances.

Use activated and deactivated hook functions

When a cached component is reactivated, it can be passed activated Hook function to perform some operations. Similarly, when a cached component is disabled, some actions can be performed through the deactivated hook function.

<template>
  <div>
    <keep-alive>
      <component :is="currentComponent" @activated="handleActivated" @deactivated="handleDeactivated"></component>
    </keep-alive>

    <button @click="switchComponent">切换组件</button>
  </div>
</template>

<script>
export default {
  methods: {
    handleActivated() {
      console.log('组件被激活');
    },
    handleDeactivated() {
      console.log('组件被禁用');
    },
  },
};
</script>

In the above example, when a cached component is activated or disabled, the handleActivated and handleDeactivated methods will be triggered respectively.

Summary

By rational use of keep-alive components, we can achieve component caching and improve page performance and user experience. We can specify the components that need to be cached or excluded through the include and exclude attributes, and control the upper limit of the number of cached component instances through the max attribute. In addition, we can also use the activated and deactivated hook functions to perform some custom operations.

I hope this article will help you understand how to properly use keep-alive for component caching. Wishing you better results in your Vue.js development!

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