/vue-best-practices

KeepAlive Component Best Practices

Impact: HIGH - <KeepAlive> caches component instances instead of destroying them. Use it to preserve state across switches, but manage cache size and freshness explicitly to avoid memory growth or stale UI.

Task List

• Use KeepAlive only where state preservation improves UX
• Set a reasonable max to cap cache size
• Declare component names for include/exclude matching
• Use onActivated/onDeactivated for cache-aware logic
• Decide how and when cached views refresh their data
• Avoid caching memory-heavy or security-sensitive views

When to Use KeepAlive

Use KeepAlive when switching between views where state should persist (tabs, multi-step forms, dashboards). Avoid it when each visit should start fresh.

BAD:

<template>
  <!-- State resets on every switch -->
  <component :is="currentTab" />
</template>

GOOD:

<template>
  <!-- State preserved between switches -->
  <KeepAlive>
    <component :is="currentTab" />
  </KeepAlive>
</template>

When NOT to Use KeepAlive

• Search or filter pages where users expect fresh results
• Memory-heavy components (maps, large tables, media players)
• Sensitive flows where data must be cleared on exit
• Components with heavy background activity you cannot pause

Limit and Control the Cache

Always cap cache size with max and restrict caching to specific components when possible.

<template>
  <KeepAlive :max="5" include="Dashboard,Settings">
    <component :is="currentView" />
  </KeepAlive>
</template>

Ensure Component Names Match include/exclude

include and exclude match the component name option. Explicitly set names for reliable caching.

<!-- TabA.vue -->
<script setup>
defineOptions({ name: 'TabA' })
</script>

<template>
  <KeepAlive include="TabA,TabB">
    <component :is="currentTab" />
  </KeepAlive>
</template>

Cache Invalidation Strategies

Vue 3 has no direct API to remove a specific cached instance. Use keys or dynamic include/exclude to force refreshes.

<script setup>
import { ref, reactive } from 'vue'

const currentView = ref('Dashboard')
const viewKeys = reactive({ Dashboard: 0, Settings: 0 })

function invalidateCache(view) {
  viewKeys[view]++
}
</script>

<template>
  <KeepAlive>
    <component :is="currentView" :key="`${currentView}-${viewKeys[currentView]}`" />
  </KeepAlive>
</template>

Lifecycle Hooks for Cached Components

Cached components are not destroyed on switch. Use activation hooks for refresh and cleanup.

<script setup>
import { onActivated, onDeactivated } from 'vue'

onActivated(() => {
  refreshData()
})

onDeactivated(() => {
  pauseTimers()
})
</script>

Router Caching and Freshness

Decide whether navigation should show cached state or a fresh view. A common pattern is to key by route when params change.

<template>
  <router-view v-slot="{ Component, route }">
    <KeepAlive>
      <component :is="Component" :key="route.fullPath" />
    </KeepAlive>
  </router-view>
</template>

If you want cache reuse but fresh data, refresh in onActivated and compare query/params before fetching.