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188 lines
7.4 KiB
Markdown
188 lines
7.4 KiB
Markdown
---
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title: Auto-imports
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description: "Nuxt auto-imports components, composables, helper functions and Vue APIs."
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---
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Nuxt auto-imports components, composables and [Vue.js APIs](https://vuejs.org/api) to use across your application without explicitly importing them.
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```vue twoslash [app.vue]
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<script setup lang="ts">
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const count = ref(1) // ref is auto-imported
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</script>
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```
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Thanks to its opinionated directory structure, Nuxt can auto-import your [`components/`](/docs/guide/directory-structure/components), [`composables/`](/docs/guide/directory-structure/composables) and [`utils/`](/docs/guide/directory-structure/utils).
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Contrary to a classic global declaration, Nuxt preserves typings, IDEs completions and hints, and **only includes what is used in your production code**.
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::note
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In the docs, every function that is not explicitly imported is auto-imported by Nuxt and can be used as-is in your code. You can find a reference for auto-imported components, composables and utilities in the [API section](/docs/api).
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::
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::note
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In the [`server`](/docs/guide/directory-structure/server) directory, Nuxt auto-imports exported functions and variables from `server/utils/`.
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::
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::note
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You can also auto-import functions exported from custom folders or third-party packages by configuring the [`imports`](/docs/api/nuxt-config#imports) section of your `nuxt.config` file.
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::
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## Built-in 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 twoslash
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<script setup lang="ts">
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/* useFetch() is auto-imported */
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const { data, refresh, status } = await useFetch('/api/hello')
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</script>
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```
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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 twoslash
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<script setup lang="ts">
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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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### 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, within the setup function of a component declared with `defineNuxtComponent`, 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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::tip{icon="i-ph-video" to="https://www.youtube.com/watch?v=ofuKRZLtOdY" target="_blank"}
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Watch a video from Alexander Lichter about handling async code in composables and fixing `Nuxt instance is unavailable` in your app.
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::
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::tip
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When using a composable that requires the Nuxt context inside a non-SFC component, you need to wrap your component with `defineNuxtComponent` instead of `defineComponent`
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::
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::read-more{to="/docs/guide/going-further/experimental-features#asynccontext" icon="i-ph-star"}
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Checkout the `asyncContext` experimental feature to use Nuxt composables in async functions.
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::
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::read-more{to="https://github.com/nuxt/nuxt/issues/14269#issuecomment-1397352832" target="_blank"}
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See the full explanation in this GitHub comment.
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::
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**Example of breaking code:**
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```ts twoslash [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 of working code:**
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```ts twoslash [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 work here
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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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:link-example{to="/docs/examples/features/auto-imports"}
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::warning
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**Auto-imported `ref` and `computed` won't be unwrapped in a component `<template>`.** :br
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This is due to how Vue works with refs that aren't top-level to the template. You can read more about it [in the Vue documentation](https://vuejs.org/guide/essentials/reactivity-fundamentals.html#caveat-when-unwrapping-in-templates).
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::
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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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<!-- TODO:twoslash: Twoslash does not support tsconfig paths yet -->
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```vue
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<script setup lang="ts">
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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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### Disabling Auto-imports
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If you want to disable auto-importing composables and utilities, you can set `imports.autoImport` to `false` in the `nuxt.config` file.
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```ts twoslash [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 auto-imports completely but it's still possible to use [explicit imports](#explicit-imports) from `#imports`.
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## Auto-imported Components
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Nuxt also automatically imports components from your `~/components` directory, although this is configured separately from auto-importing composables and utility functions.
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:read-more{to="/docs/guide/directory-structure/components"}
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To disable auto-importing components from your own `~/components` directory, you can set `components.dirs` to an empty array (though note that this will not affect components added by modules).
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```ts twoslash [nuxt.config.ts]
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export default defineNuxtConfig({
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components: {
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dirs: []
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}
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})
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```
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## Auto-import from Third-Party Packages
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Nuxt also allows auto-importing from third-party packages.
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::tip
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If you are using the Nuxt module for that package, it is likely that the module has already configured auto-imports for that package.
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::
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For example, you could enable the auto-import of the `useI18n` composable from the `vue-i18n` package like this:
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```ts twoslash [nuxt.config.ts]
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export default defineNuxtConfig({
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imports: {
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presets: [
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{
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from: 'vue-i18n',
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imports: ['useI18n']
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}
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]
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}
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})
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```
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::tip{icon="i-ph-video" to="https://www.youtube.com/watch?v=FT2LQJ2NvVI" target="_blank"}
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Watch a video from Alexander Lichter on how to easily set up custom auto imports.
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::
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