Nuxt/docs/3.api/4.advanced/2.kit.md

---
title: "Kit Utilities"
description: Nuxt Kit provides composable utilities to help interacting with Nuxt Hooks and Nuxt Builder.
---

# Kit Utilities

::ReadMore{link="/docs/guide/going-further/kit"}
::

## Modules

[source code](https://github.com/nuxt/nuxt/blob/main/packages/kit/src/module)

Modules are the building blocks of Nuxt. Kit provides a set of utilities to help you create and use modules. You can use these utilities to create your own modules or to reuse existing modules.

### `defineNuxtModule`

Define a Nuxt module, automatically merging defaults with user provided options, installing any hooks that are provided, and calling an optional setup function for full control.

#### Type

```ts
function defineNuxtModule<OptionsT extends ModuleOptions> (definition: ModuleDefinition<OptionsT> | NuxtModule<OptionsT>): NuxtModule<OptionsT>

type ModuleOptions = Record<string, any>

interface ModuleDefinition<T extends ModuleOptions = ModuleOptions> {
  meta?: ModuleMeta
  defaults?: T | ((nuxt: Nuxt) => T)
  schema?: T
  hooks?: Partial<NuxtHooks>
  setup?: (this: void, resolvedOptions: T, nuxt: Nuxt) => Awaitable<void | false | ModuleSetupReturn>
}

interface NuxtModule<T extends ModuleOptions = ModuleOptions> {
  (this: void, inlineOptions: T, nuxt: Nuxt): Awaitable<void | false | ModuleSetupReturn>
  getOptions?: (inlineOptions?: T, nuxt?: Nuxt) => Promise<T>
  getMeta?: () => Promise<ModuleMeta>
}

interface ModuleSetupReturn {
  timings?: {
    setup?: number
    [key: string]: number | undefined
  }
}

interface ModuleMeta {
  name?: string
  version?: string
  configKey?: string
  compatibility?: NuxtCompatibility
  [key: string]: unknown
}
```

#### Parameters

##### `definition`

**Type**: `ModuleDefinition<T> | NuxtModule<T>`

**Required**: `true`

A module definition object or a module function.

- `meta` (optional)

  **Type**: `ModuleMeta`

  Metadata of the module. It defines the module name, version, config key and compatibility.

- `defaults` (optional)

  **Type**: `T | ((nuxt: Nuxt) => T)`

  Default options for the module. If a function is provided, it will be called with the Nuxt instance as the first argument.

- `schema` (optional)

  **Type**: `T`

  Schema for the module options. If provided, options will be applied to the schema.

- `hooks` (optional)

  **Type**: `Partial<NuxtHooks>`

  Hooks to be installed for the module. If provided, the module will install the hooks.

- `setup` (optional)

  **Type**: `(this: void, resolvedOptions: T, nuxt: Nuxt) => Awaitable<void | false | ModuleSetupReturn>`

  Setup function for the module. If provided, the module will call the setup function.

#### Examples

```ts
// https://github.com/nuxt/starter/tree/module
import { defineNuxtModule } from '@nuxt/kit'

export interface ModuleOptions {}

export default defineNuxtModule<ModuleOptions>({
  meta: {
    name: 'my-module',
    configKey: 'myModule'
  },
  defaults: {
    test: 123
  },
  setup (options, nuxt) {
    nuxt.hook('modules:done', () => {
      console.log('My module is ready with current test option: ', options.test)
    })    
  }
})
```

### `installModule`

Install specified Nuxt module programmatically. This is helpful when your module depends on other modules. You can pass the module options as an object to `inlineOptions` and they will be passed to the module's `setup` function.

#### Type

```ts
async function installModule (moduleToInstall: string | NuxtModule, inlineOptions?: any, nuxt?: Nuxt)
```

#### Parameters

##### `moduleToInstall`

**Type**: `string` | `NuxtModule`

**Required**: `true`

The module to install. Can be either a string with the module name or a module object itself.

##### `inlineOptions`

**Type**: `any`

**Default**: `{}`

An object with the module options to be passed to the module's `setup` function.

##### `nuxt`

**Type**: `Nuxt`

**Default**: `useNuxt()`

Nuxt instance. If not provided, it will be retrieved from the context via `useNuxt()` call.

#### Examples

```ts
import { defineNuxtModule, installModule } from '@nuxt/kit'

export default defineNuxtModule<ModuleOptions>({  
  async setup (options, nuxt) {
    // will install @nuxtjs/fontaine with Roboto font and Impact fallback
    await installModule('@nuxtjs/fontaine', {
      // module configuration
      fonts: [
        {
          family: 'Roboto',
          fallbacks: ['Impact'],
          fallbackName: 'fallback-a',
        }
      ]
    })
  }
})
```

## Programmatic Usage

[source code](https://github.com/nuxt/nuxt/blob/main/packages/kit/src/loader)

Programmatic usage can be helpfull when you want to use Nuxt programmatically, for example, when building a [CLI tool](https://github.com/nuxt/cli) or [test utils](https://github.com/nuxt/nuxt/tree/main/packages/test-utils).

### `loadNuxt`

Load Nuxt programmatically. It will load the Nuxt configuration, instantiate and return the promise with Nuxt instance.

#### Type

```ts
async function loadNuxt (loadOptions?: LoadNuxtOptions): Promise<Nuxt>

interface LoadNuxtOptions extends LoadNuxtConfigOptions {
  dev?: boolean
  ready?: boolean
  rootDir?: string
  config?: LoadNuxtConfigOptions['overrides']
}
```

#### Parameters

##### `loadOptions`

**Type**: `LoadNuxtOptions`

**Default**: `{}`

Loading conditions for Nuxt. `loadNuxt` uses [`c12`](https://github.com/unjs/c12) under the hood, so it accepts the same options as `c12.loadConfig` with some additional options:

- `dev` (optional)

  **Type**: `boolean`

  **Default**: `false`

  If set to `true`, Nuxt will be loaded in development mode.

- `ready` (optional)
  
  **Type**: `boolean`
  
  **Default**: `true`
  
  If set to `true`, Nuxt will be ready to use after the `loadNuxt` call. If set to `false`, you will need to call `nuxt.ready()` to make sure Nuxt is ready to use.

- `rootDir` (optional)

  **Type**: `string`

  **Default**: `null`

  **Deprecated**: Use `cwd` option instead.

  The root directory of the Nuxt project.

- `config` (optional)

  **Type**: `LoadNuxtConfigOptions['overrides']`

  **Default**: `{}`

  **Deprecated**: Use `overrides` option instead.

  Overrides for the Nuxt configuration.

### `buildNuxt`

Build Nuxt programmatically. It will invoke the builder (currently [@nuxt/vite-builder](https://github.com/nuxt/nuxt/tree/main/packages/vite) or [@nuxt/webpack-builder](https://github.com/nuxt/nuxt/tree/main/packages/webpack)) to bundle the application.

#### Type

```ts
async function buildNuxt (nuxt: Nuxt): Promise<any>
```

#### Parameters

##### `nuxt`

**Type**: `Nuxt`

**Required**: `true`

Nuxt instance to build. It can be retrieved from the context via `useNuxt()` call.

### `loadNuxtConfig`

Load Nuxt configuration. It will return the promise with the configuration object.

#### Type

```ts
async function loadNuxtConfig (opts: LoadNuxtConfigOptions): Promise<NuxtOptions>
```

#### Parameters

##### `opts`

**Type**: `LoadNuxtConfigOptions`

**Required**: `true`

Options to pass in [`c12`](https://github.com/unjs/c12#options) `loadConfig` call.

## Compatibility

[source code](https://github.com/nuxt/nuxt/blob/main/packages/kit/src/compatibility.ts)

Kit utilities can be used in Nuxt 3, Nuxt 2 with Bridge and Nuxt 2 without Bridge. To make sure your module is compatible with all versions, you can use the `checkNuxtCompatibility`, `assertNuxtCompatibility` and `hasNuxtCompatibility` functions. They will check if the current Nuxt version meets the constraints you provide. Also you can use `isNuxt2`, `isNuxt3` and `getNuxtVersion` functions for more granular checks.

### `checkNuxtCompatibility`

Checks if constraints are met for the current Nuxt version. If not, returns an array of messages. Nuxt 2 version also checks for `bridge` support.

#### Type

```ts
async function checkNuxtCompatibility(
  constraints: NuxtCompatibility,
  nuxt?: Nuxt
): Promise<NuxtCompatibilityIssues>;

interface NuxtCompatibility {
  nuxt?: string;
  bridge?: boolean;
}

interface NuxtCompatibilityIssue {
  name: string;
  message: string;
}

interface NuxtCompatibilityIssues extends Array<NuxtCompatibilityIssue> {
  toString(): string;
}
```

#### Parameters

##### `constraints`

**Type**: `NuxtCompatibility`

**Default**: `{}`

Constraints to check for. It accepts the following properties:

- `nuxt` (optional)

  **Type**: `string`

  Nuxt version in semver format. Versions may be defined in Node.js way, for exmaple: `>=2.15.0 <3.0.0`.

- `bridge` (optional)

  **Type**: `boolean`

  If set to `true`, it will check if the current Nuxt version supports `bridge`.

##### `nuxt`

**Type**: `Nuxt`

**Default**: `useNuxt()`

Nuxt instance. If not provided, it will be retrieved from the context via `useNuxt()` call.

### `assertNuxtCompatibility`

Asserts that constraints are met for the current Nuxt version. If not, throws an error with the list of issues as string.

#### Type

```ts
async function assertNuxtCompatibility(
  constraints: NuxtCompatibility,
  nuxt?: Nuxt
): Promise<true>;

interface NuxtCompatibility {
  nuxt?: string;
  bridge?: boolean;
}
```

#### Parameters

##### `constraints`

**Type**: `NuxtCompatibility`

**Default**: `{}`

Constraints to check for. It accepts the following properties:

- `nuxt` (optional)

  **Type**: `string`

  Nuxt version in semver format. Versions may be defined in Node.js way, for exmaple: `>=2.15.0 <3.0.0`.

- `bridge` (optional)

  **Type**: `boolean`

  If set to `true`, it will check if the current Nuxt version supports `bridge`.

##### `nuxt`

**Type**: `Nuxt`

**Default**: `useNuxt()`

Nuxt instance. If not provided, it will be retrieved from the context via `useNuxt()` call.

### `hasNuxtCompatibility`

Checks if constraints are met for the current Nuxt version. Return `true` if all constraints are met, otherwise returns `false`. Nuxt 2 version also checks for `bridge` support.

#### Type

```ts
async function hasNuxtCompatibility(
  constraints: NuxtCompatibility,
  nuxt?: Nuxt
): Promise<boolean>;

interface NuxtCompatibility {
  nuxt?: string;
  bridge?: boolean;
}
```

#### Parameters

##### `constraints`

**Type**: `NuxtCompatibility`

**Default**: `{}`

Constraints to check for. It accepts the following properties:

- `nuxt` (optional)

  **Type**: `string`

  Nuxt version in semver format. Versions may be defined in Node.js way, for exmaple: `>=2.15.0 <3.0.0`.

- `bridge` (optional)

  **Type**: `boolean`

  If set to `true`, it will check if the current Nuxt version supports `bridge`.

##### `nuxt`

**Type**: `Nuxt`

**Default**: `useNuxt()`

Nuxt instance. If not provided, it will be retrieved from the context via `useNuxt()` call.

### `isNuxt2`

Checks if the current Nuxt version is 2.x.

#### Type

```ts
function isNuxt2(nuxt?: Nuxt): boolean;
```

#### Parameters

##### `nuxt`

**Type**: `Nuxt`

**Default**: `useNuxt()`

Nuxt instance. If not provided, it will be retrieved from the context via `useNuxt()` call.

### `isNuxt3`

Checks if the current Nuxt version is 3.x.

#### Type

```ts
function isNuxt3(nuxt?: Nuxt): boolean;
```

#### Parameters

##### `nuxt`

**Type**: `Nuxt`

**Default**: `useNuxt()`

Nuxt instance. If not provided, it will be retrieved from the context via `useNuxt()` call.

### `getNuxtVersion`

Returns the current Nuxt version.

#### Type

```ts
function getNuxtVersion(nuxt?: Nuxt): string;
```

#### Parameters

##### `nuxt`

**Type**: `Nuxt`

**Default**: `useNuxt()`

Nuxt instance. If not provided, it will be retrieved from the context via `useNuxt()` call.

## Auto-imports

[source code](https://github.com/nuxt/nuxt/blob/main/packages/kit/src/imports.ts)

::alert{type=info}
These functions are designed for registering your own utils, composables and Vue APIs. For pages, components and plugins, please refer to the specific sections: [Pages](#pages), [Components](#components), [Plugins](#plugins).
::

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 composables and plugins. Composables or plugins can use these functions.

### `addImports`

Add imports to the Nuxt application. It makes your imports available in the Nuxt application without the need to import them manually.

#### Type

```ts
function addImports (imports: Import | Import[]): void

interface Import {
  from: string
  priority?: number
  disabled?: boolean
  meta?: {
    description?: string
    docsUrl?: string
    [key: string]: any
  }
  type?: boolean
  typeFrom?: string
  name: string
  as?: string
}
```

#### Parameters

##### `imports`

**Type**: `Import | Import[]`

**Required**: `true`

An object or an array of objects with the following properties:

- `from` (required)

  **Type**: `string`

  Module specifier to import from.

- `priority` (optional)

  **Type**: `number`

  **Default**: `1`

  Priority of the import, if multiple imports have the same name, the one with the highest priority will be used.

- `disabled` (optional)

  **Type**: `boolean`

  If this import is disabled.

- `meta` (optional)

  **Type**: `object`

  Metadata of the import.

- `meta.description` (optional)

  **Type**: `string`

  Short description of the import.

- `meta.docsUrl` (optional)

  **Type**: `string`

  URL to the documentation.

- `meta[key]` (optional)

  **Type**: `any`

  Additional metadata.

- `type` (optional)

  **Type**: `boolean`

  If this import is a pure type import.

- `typeFrom` (optional)

  **Type**: `string`

  Using this as the from when generating type declarations.

- `name` (required)
  
  **Type**: `string`
  
  Import name to be detected.

- `as` (optional)

  **Type**: `string`

  Import as this name.

#### Examples

```ts
// https://github.com/pi0/storyblok-nuxt
import { defineNuxtModule, addImports, createResolver } from '@nuxt/kit'

export default defineNuxtModule({
  setup(options, nuxt) {
    const names = [
      "useStoryblok",
      "useStoryblokApi",
      "useStoryblokBridge",
      "renderRichText",
      "RichTextSchema"
    ];

    names.forEach((name) =>
      addImports({ name, as: name, from: "@storyblok/vue" })
    );
  }
})
```

### `addImportsDir`

Add imports from a directory to the Nuxt application. It will automatically import all files from the directory and make them available in the Nuxt application without the need to import them manually.

#### Type

```ts
function addImportsDir (dirs: string | string[], opts?: { prepend?: boolean })
```

#### Parameters

##### `dirs`

**Type**: `string | string[]`

**Required**: `true`

A string or an array of strings with the path to the directory to import from.

##### `opts`

**Type**: `{ prepend?: boolean }`

**Default**: `{}`

Options to pass to the import. If `prepend` is set to `true`, the imports will be prepended to the list of imports.

#### Examples

```ts
// https://github.com/vueuse/motion/tree/main/src/nuxt
import { defineNuxtModule, addImportsDir, createResolver } from '@nuxt/kit'

export default defineNuxtModule<ModuleOptions>({
  meta: {
    name: '@vueuse/motion',
    configKey: 'motion',
  },
  defaults: {},
  setup(options, nuxt) {
    const { resolve } = createResolver(import.meta.url)
    addImportsDir(resolve('./runtime/composables'))
  },
})
```

### `addImportsSources`

Add listed imports to the Nuxt application.

#### Type

```ts
function addImportsSources (importSources: ImportSource | ImportSource[])

interface Import {
  from: string
  priority?: number
  disabled?: boolean
  meta?: {
    description?: string
    docsUrl?: string
    [key: string]: any
  }
  type?: boolean
  typeFrom?: string
  name: string
  as?: string
}

interface ImportSource extends Import {
  imports: (PresetImport | ImportSource)[]
}

type PresetImport = Omit<Import, 'from'> | string | [name: string, as?: string, from?: string]
```

#### Parameters

##### `importSources`

**Type**: `ImportSource | ImportSource[]`

**Required**: `true`

An object or an array of objects with the following properties:

- `imports` (required)

  **Type**: `PresetImport | ImportSource[]`

  **Required**: `true`

  An object or an array of objects, which can be import names, import objects or import sources.

- `from` (required)

  **Type**: `string`

  Module specifier to import from.

- `priority` (optional)

  **Type**: `number`

  **Default**: `1`

  Priority of the import, if multiple imports have the same name, the one with the highest priority will be used.

- `disabled` (optional)

  **Type**: `boolean`

  If this import is disabled.

- `meta` (optional)

  **Type**: `object`

  Metadata of the import.

- `meta.description` (optional)

  **Type**: `string`

  Short description of the import.

- `meta.docsUrl` (optional)

  **Type**: `string`

  URL to the documentation.

- `meta[key]` (optional)

  **Type**: `any`

  Additional metadata.

- `type` (optional)

  **Type**: `boolean`

  If this import is a pure type import.

- `typeFrom` (optional)

  **Type**: `string`

  Using this as the from when generating type declarations.

- `name` (required)
  
  **Type**: `string`
  
  Import name to be detected.

- `as` (optional)

  **Type**: `string`

  Import as this name.

#### Examples

```ts
// https://github.com/elk-zone/elk
import { defineNuxtModule, addImportsSources } from '@nuxt/kit'

export default defineNuxtModule({
  setup() {
    // add imports from h3 to make them autoimported
    addImportsSources({
      from: 'h3',
      imports: ['defineEventHandler', 'getQuery', 'getRouterParams', 'readBody', 'sendRedirect'] as Array<keyotypeof import('h3')>,
    })
  }
})
```

## Components

[source code](https://github.com/nuxt/nuxt/blob/main/packages/kit/src/components.ts)

In Nuxt, components from the components directory are automatically imported by default. However, if you need to import components from an alternative directory or wish to selectively import them as needed, `@nuxt/kit` provides the `addComponentsDir` and `addComponent` methods. These utils allow you to customize the component configuration to better suit your needs.

### `addComponentsDir`

Register a directory to be scanned for components and imported only when used. Keep in mind, that this does not register components globally, until you specify `global: true` option.

#### Type

```ts
async function addComponentsDir (dir: ComponentsDir): void

interface ComponentsDir {
  path: string
  pattern?: string | string[]
  ignore?: string[]
  prefix?: string
  pathPrefix?: boolean
  enabled?: boolean
  prefetch?: boolean
  preload?: boolean
  isAsync?: boolean
  extendComponent?: (component: Component) => Promise<Component | void> | (Component | void)
  global?: boolean
  island?: boolean
  watch?: boolean
  extensions?: string[]
  transpile?: 'auto' | boolean
}

interface Component {
  pascalName: string
  kebabName: string
  export: string
  filePath: string
  shortPath: string
  chunkName: string
  prefetch: boolean
  preload: boolean
  global?: boolean
  island?: boolean
  mode?: 'client' | 'server' | 'all'
  priority?: number
}
```

#### Parameters

##### `dir`

**Type**: `ComponentsDir`

**Required**: `true`

An object with the following properties:

- `path` (required)

  **Type**: `string`

  Path (absolute or relative) to the directory containing your components.
  You can use Nuxt aliases (~ or @) to refer to directories inside project or directly use an npm package path similar to require.

- `pattern` (optional)

  **Type**: `string | string[]`

  Accept Pattern that will be run against specified path.

- `ignore` (optional)

  **Type**: `string[]`

  Ignore patterns that will be run against specified path.

- `prefix` (optional)

  **Type**: `string`

  Prefix all matched components with this string.

- `pathPrefix` (optional)

  **Type**: `boolean`

  Prefix component name by its path.

- `enabled` (optional)

  **Type**: `boolean`

  Ignore scanning this directory if set to `true`.

- `prefetch` (optional)

  **Type**: `boolean`

  These properties (prefetch/preload) are used in production to configure how components with Lazy prefix are handled by webpack via its magic comments.
  Learn more on [webpack documentation](https://webpack.js.org/api/module-methods/#magic-comments)

- `preload` (optional)

  **Type**: `boolean`

  These properties (prefetch/preload) are used in production to configure how components with Lazy prefix are handled by webpack via its magic comments.
  Learn more on [webpack documentation](https://webpack.js.org/api/module-methods/#magic-comments)

- `isAsync` (optional)

  **Type**: `boolean`

  This flag indicates, component should be loaded async (with a separate chunk) regardless of using Lazy prefix or not.

- `extendComponent` (optional)

  **Type**: `(component: Component) => Promise<Component | void> | (Component | void)`

  A function that will be called for each component found in the directory. It accepts a component object and should return a component object or a promise that resolves to a component object.

- `global` (optional)

  **Type**: `boolean`

  **Default**: `false`

  If enabled, registers components to be globally available.

- `island` (optional)

  **Type**: `boolean`

  If enabled, registers components as islands.

- `watch` (optional)

  **Type**: `boolean`

  Watch specified path for changes, including file additions and file deletions.

- `extensions` (optional)

  **Type**: `string[]`

  Extensions supported by Nuxt builder.

- `transpile` (optional)

  **Type**: `'auto' | boolean`

  Transpile specified path using build.transpile. If set to `'auto'`, it will set `transpile: true` if `node_modules/` is in path.

### `addComponent`

Register a component to be automatically imported.

#### Type

```ts
async function addComponent (opts: AddComponentOptions): void

interface AddComponentOptions {
  name: string,
  filePath: string,
  pascalName?: string,
  kebabName?: string,
  export?: string,
  shortPath?: string,
  chunkName?: string,
  prefetch?: boolean,
  preload?: boolean,
  global?: boolean,
  island?: boolean,
  mode?: 'client' | 'server' | 'all',
  priority?: number,
}
```

#### Parameters

##### `opts`

**Type**: `AddComponentOptions`

**Required**: `true`

An object with the following properties:

- `name` (required)

  **Type**: `string`

  Component name.

- `filePath` (required)

  **Type**: `string`

  Path to the component.

- `pascalName` (optional)

  **Type**: `pascalCase(opts.name)`

  Pascal case component name. If not provided, it will be generated from the component name.

- `kebabName` (optional)

  **Type**: `kebabCase(opts.name)`

  Kebab case component name. If not provided, it will be generated from the component name.

- `export` (optional)

  **Type**: `string`

  **Default**: `'default'`

  Specify named or default export. If not provided, it will be set to `'default'`.

- `shortPath` (optional)

  **Type**: `string`

  Short path to the component. If not provided, it will be generated from the component path.

- `chunkName` (optional)

  **Type**: `string`

  **Default**: `'components/' + kebabCase(opts.name)`

  Chunk name for the component. If not provided, it will be generated from the component name.

- `prefetch` (optional)

  **Type**: `boolean`

  These properties (prefetch/preload) are used in production to configure how components with Lazy prefix are handled by webpack via its magic comments.
  Learn more on [webpack documentation](https://webpack.js.org/api/module-methods/#magic-comments)

- `preload` (optional)

  **Type**: `boolean`

  These properties (prefetch/preload) are used in production to configure how components with Lazy prefix are handled by webpack via its magic comments.
  Learn more on [webpack documentation](https://webpack.js.org/api/module-methods/#magic-comments)

- `global` (optional)

  **Type**: `boolean`

  **Default**: `false`

  If enabled, registers component to be globally available.

- `island` (optional)

  **Type**: `boolean`

  If enabled, registers component as island. You  can read more about islands in [<NuxtIsland/>](/docs/api/components/nuxt-island#nuxtisland) component description.

- `mode` (optional)

  **Type**: `'client' | 'server' | 'all'`

  **Default**: `'all'`

  This options indicates if component should render on client, server or both. By default, it will render on both client and server.

- `priority` (optional)

  **Type**: `number`

  **Default**: `1`

  Priority of the component, if multiple components have the same name, the one with the highest priority will be used.

## Context

[source code](https://github.com/nuxt/nuxt/blob/main/packages/kit/src/context.ts)

Nuxt modules allow you to enhance Nuxt's capabilities. They offer a structured way to keep your code organized and modular. If you're looking to break down your module into smaller components, Nuxt offers the `useNuxt` and `tryUseNuxt` functions. These functions enable you to conveniently access the Nuxt instance from the context without having to pass it as argument.

::alert{type=info}
When you're working with the `setup` function in Nuxt modules, Nuxt is already provided as the second argument. This means you can directly utilize it without needing to call `useNuxt()`. You can look at [Nuxt Site Config](https://github.com/harlan-zw/nuxt-site-config) as an example of usage.
::

### `useNuxt`

Get the Nuxt instance from the context. It will throw an error if Nuxt is not available.

#### Type

```ts
function useNuxt(): Nuxt

interface Nuxt {
  options: NuxtOptions
  hooks: Hookable<NuxtHooks>
  hook: Nuxt['hooks']['hook']
  callHook: Nuxt['hooks']['callHook']
  addHooks: Nuxt['hooks']['addHooks']
  ready: () => Promise<void>
  close: () => Promise<void>
  server?: any
  vfs: Record<string, string>
  apps: Record<string, NuxtApp>
}
```

#### Examples

::code-group

```ts [setupTranspilation.ts]
// https://github.com/Lexpeartha/nuxt-xstate/blob/main/src/parts/transpile.ts
import { useNuxt } from '@nuxt/kit'

export const setupTranspilation = () => {
  const nuxt = useNuxt()

  nuxt.options.build.transpile = nuxt.options.build.transpile || []

  if (nuxt.options.builder === '@nuxt/webpack-builder') {
    nuxt.options.build.transpile.push(
      'xstate',
    )
  }
}
```

```ts [module.ts]
import { useNuxt } from '@nuxt/kit'
import { setupTranspilation } from './setupTranspilation'

export default defineNuxtModule({
  setup() {
    setupTranspilation()
  }
})
```

::

### `tryUseNuxt`

Get the Nuxt instance from the context. It will return `null` if Nuxt is not available.

#### Type

```ts
function tryUseNuxt(): Nuxt | null

interface Nuxt {
  options: NuxtOptions
  hooks: Hookable<NuxtHooks>
  hook: Nuxt['hooks']['hook']
  callHook: Nuxt['hooks']['callHook']
  addHooks: Nuxt['hooks']['addHooks']
  ready: () => Promise<void>
  close: () => Promise<void>
  server?: any
  vfs: Record<string, string>
  apps: Record<string, NuxtApp>
}
```

#### Examples

::code-group

```ts [requireSiteConfig.ts]
// https://github.com/harlan-zw/nuxt-site-config/blob/main/test/assertions.test.ts
import { tryUseNuxt } from '@nuxt/kit'

interface SiteConfig {
  title: string
}

export const requireSiteConfig = (): SiteConfig => {
  const nuxt = tryUseNuxt()
  if (!nuxt) {
    return { title: null }
  }
  return nuxt.options.siteConfig
}
```

```ts [module.ts]
import { useNuxt } from '@nuxt/kit'
import { requireSiteConfig } from './requireSiteConfig'

export default defineNuxtModule({
  setup(_, nuxt) {
    const config = requireSiteConfig()
    nuxt.options.app.head.title = config.title
  }
})
```

::

## Pages

[source code](https://github.com/nuxt/nuxt/blob/main/packages/kit/src/pages.ts)

### `extendPages`

In Nuxt 3, routes are automatically generated based on the structure of the files in the `pages` directory. However, there may be scenarios where you'd want to customize these routes. For instance, you might need to add a route for a dynamic page not generated by Nuxt, remove an existing route, or modify the configuration of a route. For such customizations, Nuxt 3 offers the `extendPages` feature, which allows you to extend and alter the pages configuration.

#### Type

```ts
function extendPages (callback: (pages: NuxtPage[]) => void): void

type NuxtPage = {
  name?: string
  path: string
  file?: string
  meta?: Record<string, any>
  alias?: string[] | string
  redirect?: RouteLocationRaw
  children?: NuxtPage[]
}
```

#### Parameters

##### `callback`

**Type**: `(pages: NuxtPage[]) => void`

**Required**: `true`

A function that will be called with the pages configuration. You can alter this array by adding, deleting, or modifying its elements. Note: You should modify the provided pages array directly, as changes made to a copied array will not be reflected in the configuration.

#### Examples

```ts
// https://github.com/nuxt-modules/prismic/blob/master/src/module.ts
import { createResolver, defineNuxtModule, extendPages } from '@nuxt/kit'

export default defineNuxtModule({
  setup(options) {
    const resolver = createResolver(import.meta.url)

    extendPages((pages) => {
      pages.unshift({
        name: 'prismic-preview',
        path: '/preview',
        file: resolver.resolve('runtime/preview.vue')
       })
    })
  }
})
```

### `extendRouteRules`

Nuxt is powered by the [Nitro](https://nitro.unjs.io) server engine. With Nitro, you can incorporate high-level logic directly into your configuration, which is usefull for actions like redirects, proxying, caching, and appending headers to routes. This configuration works by associating route patterns with specific route settings.

::alert{type=info icon=👉}
You can read more about Nitro route rules in the [Nitro documentation](https://nitro.unjs.io/guide/routing#route-rules).
::

#### Type

```ts
function extendRouteRules (route: string, rule: NitroRouteConfig, options: ExtendRouteRulesOptions): void

interface NitroRouteConfig {
  cache?: CacheOptions | false;
  headers?: Record<string, string>;
  redirect?: string | { to: string; statusCode?: HTTPStatusCode };
  prerender?: boolean;
  proxy?: string | ({ to: string } & ProxyOptions);
  isr?: number | boolean;
  cors?: boolean;
  swr?: boolean | number;
  static?: boolean | number;
}

interface ExtendRouteRulesOptions {
  override?: boolean
}

interface CacheOptions {
  swr?: boolean
  name?: string
  group?: string
  integrity?: any
  maxAge?: number
  staleMaxAge?: number
  base?: string
  headersOnly?: boolean
}

// See https://www.jsdocs.io/package/h3#ProxyOptions
interface ProxyOptions {
  headers?: RequestHeaders | HeadersInit;
  fetchOptions?: RequestInit & { duplex?: Duplex } & {
    ignoreResponseError?: boolean;
  };
  fetch?: typeof fetch;
  sendStream?: boolean;
  streamRequest?: boolean;
  cookieDomainRewrite?: string | Record<string, string>;
  cookiePathRewrite?: string | Record<string, string>;
  onResponse?: (event: H3Event, response: Response) => void;
}
```

#### Parameters

##### `route`

**Type**: `string`

**Required**: `true`

A route pattern to match against.

##### `rule`

**Type**: `NitroRouteConfig`

**Required**: `true`

A route configuration to apply to the matched route.

##### `options`

**Type**: `ExtendRouteRulesOptions`

**Default**: `{}`

Options to pass to the route configuration. If `override` is set to `true`, it will override the existing route configuration.

#### Examples

```ts
// https://github.com/directus/website/blob/main/modules/redirects.ts
import { createResolver, defineNuxtModule, extendRouteRules, extendPages } from '@nuxt/kit'

export default defineNuxtModule({
  setup(options) {
    const resolver = createResolver(import.meta.url)

    extendPages((pages) => {
      pages.unshift({
        name: 'preview-new',
        path: '/preview-new',
        file: resolver.resolve('runtime/preview.vue')
       })
    })

    extendRouteRules('/preview', {
      redirect: {
        to: '/preview-new',
        statusCode: 302
      }
    })

    extendRouteRules('/preview-new', {
      cache: {
        maxAge: 60 * 60 * 24 * 7
      }
    })
  }
})
```

### `addRouteMiddleware`

Registers route middlewares to be available for all routes or for specific routes.

Route middlewares can be also defined in plugins via [`addRouteMiddleware`](/docs/api/utils/add-route-middleware) composable.

::alert{type=info icon=👉}
Read more about route middlewares in the [Route middleware documentation](/docs/getting-started/routing#route-middleware).
::

#### Type

```ts
function addRouteMiddleware (input: NuxtMiddleware | NuxtMiddleware[], options: AddRouteMiddlewareOptions)

type NuxtMiddleware = {
  name: string
  path: string
  global?: boolean
}

interface AddRouteMiddlewareOptions {
  override?: boolean
}
```

#### Parameters

##### `input`

**Type**: `NuxtMiddleware | NuxtMiddleware[]`

**Required**: `true`

A middleware object or an array of middleware objects with the following properties:

- `name` (required)

  **Type**: `string`

  Middleware name.

- `path` (required)

  **Type**: `string`

  Path to the middleware.

- `global` (optional)

  **Type**: `boolean`

  If enabled, registers middleware to be available for all routes.

##### `options`

**Type**: `AddRouteMiddlewareOptions`

**Default**: `{}`

Options to pass to the middleware. If `override` is set to `true`, it will override the existing middleware with the same name.

#### Examples

::code-group

```ts [runtime/auth.ts]
export default defineNuxtRouteMiddleware((to, from) => {
  // isAuthenticated() is an example method verifying if a user is authenticated
  if (isAuthenticated() === false) {
    return navigateTo('/login')
  }
})
```

```ts
import { createResolver, defineNuxtModule, addRouteMiddleware } from '@nuxt/kit'

export default defineNuxtModule({
  setup() {
    const resolver = createResolver(import.meta.url)

    addRouteMiddleware({
      name: 'auth',
      path: resolver.resolve('runtime/auth.ts'),
      global: true
    })
  }
})
```

::

## Layout

[source code](https://github.com/nuxt/nuxt/blob/main/packages/kit/src/layout.ts)

### `addLayout`

Register template as layout and add it to the layouts array.

#### Type

```ts
function addLayout (layout: NuxtTemplate, name: string): void

interface NuxtTemplate {
  src?: string
  filename?: string
  dst?: string
  options?: Record<string, any>
  getContents?: (data: Record<string, any>) => string | Promise<string>
  write?: boolean
}
```

#### Parameters

##### `layout`

**Type**: `NuxtTemplate`

**Required**: `true`

A template object with the following properties:

- `src` (optional)

  **Type**: `string`

  Path to the template. If `src` is not provided, `getContents` must be provided instead.

- `filename` (optional)

  **Type**: `string`

  Filename of the template. If `filename` is not provided, it will be generated from the `src` path. In this case, the `src` option is required.

- `dst` (optional)

  **Type**: `string`

  Path to the destination file. If `dst` is not provided, it will be generated from the `filename` path and nuxt `buildDir` option.

- `options` (optional)

  **Type**: `Options`

  Options to pass to the template.

- `getContents` (optional)

  **Type**: `(data: Options) => string | Promise<string>`

  A function that will be called with the `options` object. It should return a string or a promise that resolves to a string. If `src` is provided, this function will be ignored.

- `write` (optional)
  
    **Type**: `boolean`

    If set to `true`, the template will be written to the destination file. Otherwise, the template will be used only in virtual filesystem.

## Plugins

[source code](https://github.com/nuxt/nuxt/blob/main/packages/kit/src/plugin.ts)

### `addPlugin`

Registers a Nuxt plugin and to the plugins array.

#### Type

```ts
function addPlugin (plugin: NuxtPlugin | string, options: AddPluginOptions): NuxtPlugin

interface NuxtPlugin {
  src: string
  mode?: 'all' | 'server' | 'client'
  order?: number
}

interface AddPluginOptions { append?: boolean }
```

#### Parameters

##### `plugin`

**Type**: `NuxtPlugin | string`

**Required**: `true`

A plugin object or a string with the path to the plugin. If a string is provided, it will be converted to a plugin object with `src` set to the string value. If a plugin object is provided, it must have the following properties:

- `src` (required)

  **Type**: `string`

  Path to the plugin.

- `mode` (optional)

  **Type**: `'all' | 'server' | 'client'`

  **Default**: `'all'`

  If set to `'all'`, the plugin will be included in both client and server bundles. If set to `'server'`, the plugin will only be included in the server bundle. If set to `'client'`, the plugin will only be included in the client bundle. You can also use `.client` and `.server` modifiers when specifying `src` option to use plugin only in client or server side.

- `order` (optional)

  **Type**: `number`

  **Default**: `0`

  Order of the plugin. This allows more granular control over plugin order and should only be used by advanced users. Lower numbers run first, and user plugins default to `0`. It's recommended to set `order` to a number between `-20` for `pre`-plugins (plugins that run before Nuxt plugins) and `20` for `post`-plugins (plugins that run after Nuxt plugins).

::alert{type=warning}
Don't use `order` unless you know what you're doing. For most plugins, the default `order` of `0` is sufficient. To append a plugin to the end of the plugins array, use the `append` option instead.
::

##### `options`

**Type**: `AddPluginOptions`

**Default**: `{}`

Options to pass to the plugin. If `append` is set to `true`, the plugin will be appended to the plugins array instead of prepended.

#### Examples

::code-group

```ts [module.ts]
import { createResolver, defineNuxtModule, addPlugin } from '@nuxt/kit'

export default defineNuxtModule({
  setup() {
    const resolver = createResolver(import.meta.url)

    addPlugin({
      src: resolver.resolve('runtime/plugin.js'),
      mode: 'client'
    })
  }
})
```

```ts [runtime/plugin.js]
// https://github.com/nuxt/nuxters
export default defineNuxtPlugin((nuxtApp) => {
  const colorMode = useColorMode()

  nuxtApp.hook('app:mounted', () => {
    if (colorMode.preference !== 'dark') {
      colorMode.preference = 'dark'
    }
  })
})
```

::

### `addPluginTemplate`

Adds a template and registers as a nuxt plugin. This is useful for plugins that need to generate code at build time.

#### Type

```ts
function addPluginTemplate (pluginOptions: NuxtPluginTemplate, options: AddPluginOptions): NuxtPlugin

interface NuxtPluginTemplate<Options = Record<string, any>> {
  src?: string,
  filename?: string,
  dst?: string,
  mode?: 'all' | 'server' | 'client',
  options?: Options,
  getContents?: (data: Options) => string | Promise<string>,
  write?: boolean,
  order?: number
}

interface AddPluginOptions { append?: boolean }

interface NuxtPlugin {
  src: string
  mode?: 'all' | 'server' | 'client'
  order?: number
}
```

#### Parameters

##### `pluginOptions`

**Type**: `NuxtPluginTemplate`

**Required**: `true`

A plugin template object with the following properties:

- `src` (optional)

  **Type**: `string`

  Path to the template. If `src` is not provided, `getContents` must be provided instead.

- `filename` (optional)

  **Type**: `string`

  Filename of the template. If `filename` is not provided, it will be generated from the `src` path. In this case, the `src` option is required.

- `dst` (optional)

  **Type**: `string`

  Path to the destination file. If `dst` is not provided, it will be generated from the `filename` path and nuxt `buildDir` option.

- `mode` (optional)

  **Type**: `'all' | 'server' | 'client'`

  **Default**: `'all'`

  If set to `'all'`, the plugin will be included in both client and server bundles. If set to `'server'`, the plugin will only be included in the server bundle. If set to `'client'`, the plugin will only be included in the client bundle. You can also use `.client` and `.server` modifiers when specifying `src` option to use plugin only in client or server side.

- `options` (optional)

  **Type**: `Options`

  Options to pass to the template.

- `getContents` (optional)

  **Type**: `(data: Options) => string | Promise<string>`

  A function that will be called with the `options` object. It should return a string or a promise that resolves to a string. If `src` is provided, this function will be ignored.

- `write` (optional)
  
    **Type**: `boolean`

    If set to `true`, the template will be written to the destination file. Otherwise, the template will be used only in virtual filesystem.

- `order` (optional)

  **Type**: `number`

  **Default**: `0`

  Order of the plugin. This allows more granular control over plugin order and should only be used by advanced users. Lower numbers run first, and user plugins default to `0`. It's recommended to set `order` to a number between `-20` for `pre`-plugins (plugins that run before Nuxt plugins) and `20` for `post`-plugins (plugins that run after Nuxt plugins).

::alert{type=warning}
Don't use `order` unless you know what you're doing. For most plugins, the default `order` of `0` is sufficient. To append a plugin to the end of the plugins array, use the `append` option instead.
::
  
##### `options`

**Type**: `AddPluginOptions`

**Default**: `{}`

Options to pass to the plugin. If `append` is set to `true`, the plugin will be appended to the plugins array instead of prepended.

#### Examples

::code-group

```ts [module.ts]
// https://github.com/vuejs/vuefire
import { createResolver, defineNuxtModule, addPluginTemplate } from '@nuxt/kit'

export default defineNuxtModule({
  setup() {
    const resolver = createResolver(import.meta.url)

    addPluginTemplate({
      src: resolve(templatesDir, 'plugin.ejs'),
      options: {
        ...options,
        ssr: nuxt.options.ssr,
      },
    })
  }
})
```

```ts [runtime/plugin.ejs]
import { VueFire, useSSRInitialState } from 'vuefire'
import { defineNuxtPlugin } from '#app'

export default defineNuxtPlugin((nuxtApp) => {
  const firebaseApp = nuxtApp.$firebaseApp

  nuxtApp.vueApp.use(VueFire, { firebaseApp })

  <% if(options.ssr) { %>
  if (process.server) {
    nuxtApp.payload.vuefire = useSSRInitialState(undefined, firebaseApp)
  } else if (nuxtApp.payload?.vuefire) {
    useSSRInitialState(nuxtApp.payload.vuefire, firebaseApp)
  }
  <% } %>
})
```

## Templates

[source code](https://github.com/nuxt/nuxt/blob/main/packages/kit/src/template.ts)

- `addTemplate(templateOptions)`
- `addTypeTemplate(templateOptions)`
- `updateTemplates({ filter?: ResolvedNuxtTemplate => boolean })`

## Nitro

[source code](https://github.com/nuxt/nuxt/blob/main/packages/kit/src/nitro.ts)

- `addServerHandler (handler)`
- `addDevServerHandler (handler)`
- `useNitro()` (only usable after `ready` hook)
- `addServerPlugin`
- `addPrerenderRoutes`

## Resolving

[source code](https://github.com/nuxt/nuxt/blob/main/packages/kit/src/resolve.ts)

- `resolvePath (path, resolveOptions?)`
- `resolveAlias (path, aliases?)`
- `findPath (paths, resolveOptions?)`
- `createResolver (base)`

## Logging

[source code](https://github.com/nuxt/nuxt/blob/main/packages/kit/src/logger.ts)

- `useLogger(scope?)`

## Builder

[source code](https://github.com/nuxt/nuxt/blob/main/packages/kit/src/build.ts)

- `extendWebpackConfig(callback, options?)`
- `extendViteConfig(callback, options?)`
- `addWebpackPlugin(webpackPlugin, options?)`
- `addVitePlugin(vitePlugin, options?)`

## Examples

### Accessing Nuxt Vite Config

If you are building an integration that needs access to the runtime Vite or webpack config that Nuxt uses, it is possible to extract this using Kit utilities.

Some examples of projects doing this already:

- [histoire](https://github.com/histoire-dev/histoire/blob/main/packages/histoire-plugin-nuxt/src/index.ts)
- [nuxt-vitest](https://github.com/danielroe/nuxt-vitest/blob/main/packages/nuxt-vitest/src/config.ts)
- [@storybook-vue/nuxt](https://github.com/storybook-vue/nuxt/blob/main/src/preset.ts)

Here is a brief example of how you might access the Vite config from a project; you could implement a similar approach to get the webpack configuration.

```js
import { loadNuxt, buildNuxt } from '@nuxt/kit'

// https://github.com/nuxt/nuxt/issues/14534
async function getViteConfig() {
  const nuxt = await loadNuxt({ cwd: process.cwd(), dev: false, overrides: { ssr: false } })
  return new Promise((resolve, reject) => {
    nuxt.hook('vite:extendConfig', (config, { isClient }) => {
      if (isClient) {
        resolve(config)
        throw new Error('_stop_')
      }
    })
    buildNuxt(nuxt).catch((err) => {
      if (!err.toString().includes('_stop_')) {
        reject(err)
      }
    })
  }).finally(() => nuxt.close())
}

const viteConfig = await getViteConfig()
console.log(viteConfig)
```