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121 lines
4.7 KiB
Markdown
121 lines
4.7 KiB
Markdown
---
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description: "Nuxt auto-imports helper functions, composables and Vue APIs."
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---
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# Auto imports
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Nuxt auto-imports helper functions, composables and Vue APIs to use across your application without explicitly importing them. Based on the directory structure, every Nuxt application can also use auto-imports for its own components, composables and plugins. Components, composables or plugins can use these functions.
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Contrary to a classic global declaration, Nuxt preserves typings and IDEs completions and hints, and only includes what is actually used in your production code.
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::alert{type=info icon=💡}
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In the documentation, every function that is not explicitly imported is auto-imported by Nuxt and can be used as-is in your code.
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You can find a reference for auto-imported [composables](/docs/api/composables/use-async-data) and [utilities](/docs/api/utils/dollarfetch) in the API section.
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::
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::alert{type=info}
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In the [server directory](/docs/guide/directory-structure/server), we auto import exported functions and variables from `server/utils/`.
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::
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## Built-in Auto-imports
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### Nuxt Auto-imports
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Nuxt auto-imports functions and composables to perform [data fetching](/docs/getting-started/data-fetching), get access to the [app context](/docs/api/composables/use-nuxt-app) and [runtime config](/docs/guide/going-further/runtime-config), manage [state](/docs/getting-started/state-management) or define components and plugins.
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```vue
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<script setup>
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/* useAsyncData() and $fetch() are auto-imported */
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const { data, refresh, pending } = await useAsyncData('/api/hello', () => $fetch('/api/hello'))
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</script>
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```
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### Vue Auto-imports
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Vue 3 exposes Reactivity APIs like `ref` or `computed`, as well as lifecycle hooks and helpers that are auto-imported by Nuxt.
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```vue
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<script setup>
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/* ref() and computed() are auto-imported */
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const count = ref(1)
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const double = computed(() => count.value * 2)
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</script>
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```
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### Using Vue and Nuxt composables
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<!-- TODO: move to separate page with https://github.com/nuxt/nuxt/issues/14723 and add more information -->
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When you are using the built-in composition API composables provided by Vue and Nuxt, be aware that many of them rely on being called in the right _context_.
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During a component lifecycle, Vue tracks the temporary instance of the current component (and similarly, Nuxt tracks a temporary instance of `nuxtApp`) via a global variable, and then unsets it in same tick. This is essential when server rendering, both to avoid cross-request state pollution (leaking a shared reference between two users) and to avoid leakage between different components.
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That means that (with very few exceptions) you cannot use them outside a Nuxt plugin, Nuxt route middleware or Vue setup function. On top of that, you must use them synchronously - that is, you cannot use `await` before calling a composable, except within `<script setup>` blocks, in `defineNuxtPlugin` or in `defineNuxtRouteMiddleware`, where we perform a transform to keep the synchronous context even after the `await`.
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If you get an error message like `Nuxt instance is unavailable` then it probably means you are calling a Nuxt composable in the wrong place in the Vue or Nuxt lifecycle.
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See the full explanation in this [comment](https://github.com/nuxt/framework/issues/5740#issuecomment-1229197529).
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::NeedContribution
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::
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#### Example
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**Example:** Breaking code:
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```ts [composables/example.ts]
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// trying to access runtime config outside a composable
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const config = useRuntimeConfig()
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export const useMyComposable = () => {
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// accessing runtime config here
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}
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```
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**Example:** Fixing the error:
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```ts [composables/example.ts]
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export const useMyComposable = () => {
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// Because your composable is called in the right place in the lifecycle,
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// useRuntimeConfig will also work
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const config = useRuntimeConfig()
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// ...
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}
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```
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## Directory-based Auto-imports
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Nuxt directly auto-imports files created in defined directories:
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- `components/` for [Vue components](/docs/guide/directory-structure/components).
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- `composables/` for [Vue composables](/docs/guide/directory-structure/composables).
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- `utils/` for helper functions and other utilities.
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## Explicit Imports
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Nuxt exposes every auto-import with the `#imports` alias that can be used to make the import explicit if needed:
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```vue
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<script setup>
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import { ref, computed } from '#imports'
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const count = ref(1)
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const double = computed(() => count.value * 2)
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</script>
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```
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## Disable Auto-imports
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In case you want to disable auto-imports, you can set `imports.autoImport` to `false`.
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```ts [nuxt.config.ts]
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export default defineNuxtConfig({
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imports: {
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autoImport: false
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}
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})
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```
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This will disable implicit auto imports completely but it's still possible to use [Explicit Imports](#explicit-imports).
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