Use keep-alive to solve the problem of repeated loading during Vue component switching and preserve component state. 1. It caches dynamic components to avoid destruction and reconstruction, and maintains the content of the input box, scroll position, etc.; 2. It is often used in scenarios such as tab switching, pop-up windows, sidebars, etc.; 3. Pay attention to cleaning up timer and event monitoring to prevent exceptions; 4. Control the cache range through include and exclude attributes, and give priority to include precise cache; 5. Reasonable use can improve the user experience, but it is necessary to avoid abuse causing excessive memory or confusing status.

Use keep-alive to solve the problem of repeated loading of Vue components during switching. When you want a component to remain state after multiple switches instead of re-rendering each time, you should consider using keep-alive .

Cache dynamic component state

The most common usage scenario is to cooperate with dynamic components such as <component :is="xxx"></component> . For example, you have two tab pages, namely "Homepage" and "Settings". If you do not add keep-alive every time you switch, the component will be destroyed and rebuilt, and the input box content, scroll position, etc. will be reset.

After adding keep-alive , the component will be cached and can maintain its original state when it switches back again.
For example:

 <keep-alive>
  <component :is="currentTabComponent" />
</keep-alive>

After writing this way, no matter how many times you switch back and forth between several tabs, each component will only be initialized once, and subsequently it will be restored from the cache.

Note: If there are timers or event listening in the component, remember to clean up and restore during deactivated and activated life cycles, otherwise problems will occur.

Components that need to be switched frequently but do not want to be loaded repeatedly

Although some components are not dynamic components, they will frequently appear/hide, such as pop-up windows, sidebars, and content in folded panels. In this case, keep-alive can also be used to avoid repeated requests for data or re-rendering.

However, this situation should be used with caution, because not all components are suitable for caching. A pop-up window like that that requires refreshing data every time it is opened is not suitable, otherwise the user may not see the latest information.

Applicable situations such as:

• Pop-up window with local form
• Filter panel with complex states
• Steps and Process Components that the user has already operated

Control which components are cached

keep-alive provides two properties: include and exclude , which can be used to control which components need to be cached and which do not.

• include : caches only components with specified names
• exclude : Exclude components with specified names do not cache

It is recommended to give priority to include , which can control the cache range more accurately and avoid accidentally cached too much memory, causing excessive memory usage.

For example:

 <keep-alive>
  <component :is="currentTabComponent" v-if="currentTabComponent" />
</keep-alive>

Or a little more refined:

 <keep-alive>
  <component :is="currentTabComponent" v-if="currentTabComponent" include="Home,UserInfo" />
</keep-alive>

In this way, only Home and UserInfo will be cached, and other components will still be destroyed and rebuilt normally.

Basically that's it. Reasonable use of keep-alive can improve the user experience, but you should also be careful not to abuse it, otherwise it may lead to excessive memory usage or confusing state.

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