feat: improve typing of config

packages/nuxt3/src/builder/builder.ts

@@ -254,7 +254,7 @@ export default class Builder {
     }
   }
 
-  globPathWithExtensions (path) {
+  globPathWithExtensions(path: string) {
     return `${path}/**/*.{${this.supportedExtensions.join(',')}}`
   }
 
@@ -278,7 +278,7 @@ export default class Builder {
       this.resolveMiddleware(templateContext)
     ])
 
-    await this.resolvePlugins(templateContext)
+    await this.resolvePlugins()
 
     this.addOptionalTemplates(templateContext)
 
@@ -293,7 +293,7 @@ export default class Builder {
 
   async normalizePlugins () {
     // options.extendPlugins allows for returning a new plugins array
-    if (typeof this.options.extendPlugins === 'function') {
+    if (this.options.extendPlugins instanceof Function) {
       const extendedPlugins = this.options.extendPlugins(this.options.plugins)
 
       if (Array.isArray(extendedPlugins)) {
@@ -340,7 +340,7 @@ export default class Builder {
     )
   }
 
-  addOptionalTemplates (templateContext) {
+  addOptionalTemplates(templateContext) {
     if (this.options.build.indicator) {
       // templateContext.templateFiles.push('components/nuxt-build-indicator.vue')
     }
@@ -350,19 +350,19 @@ export default class Builder {
     }
   }
 
-  async resolveFiles (dir, cwd = this.options.srcDir) {
+  async resolveFiles(dir, cwd = this.options.srcDir) {
     return this.ignore.filter(await glob(this.globPathWithExtensions(dir), {
       cwd,
       follow: this.options.build.followSymlinks
     }))
   }
 
-  async resolveRelative (dir) {
+  async resolveRelative(dir) {
     const dirPrefix = new RegExp(`^${dir}/`)
     return (await this.resolveFiles(dir)).map(file => ({ src: file.replace(dirPrefix, '') }))
   }
 
-  async resolveApp ({ templateVars }) {
+  async resolveApp({ templateVars }) {
     templateVars.appPath = 'nuxt-app/app.tutorial.vue'
 
     for (const appFile of this.appFiles) {
@@ -376,7 +376,7 @@ export default class Builder {
     templateVars.hasApp = false
   }
 
-  async resolveLayouts ({ templateVars, templateFiles }) {
+  async resolveLayouts({ templateVars, templateFiles }) {
     if (!this.options.features.layouts) {
       return
     }
@@ -414,7 +414,7 @@ export default class Builder {
     }
   }
 
-  async resolvePages (templateContext) {
+  async resolvePages(templateContext) {
     const { templateVars } = templateContext
 
     const pagesDir = path.join(this.options.srcDir, this.options.dir.pages)
@@ -475,7 +475,7 @@ export default class Builder {
     this.routes = templateVars.router.routes
   }
 
-  async resolveStore ({ templateVars, templateFiles }) {
+  async resolveStore({ templateVars, templateFiles }) {
     // Add store if needed
     if (!this.options.features.store || !this.options.store) {
       return
@@ -515,7 +515,7 @@ export default class Builder {
   async resolveCustomTemplates (templateContext) {
     // Sanitize custom template files
     this.options.build.templates = this.options.build.templates.map((t) => {
-      const src = t.src || t
+      const src = typeof t === 'string' ? t : t.src
       return {
         src: r(this.options.srcDir, src),
         dst: t.dst || path.basename(src),
@@ -524,7 +524,7 @@ export default class Builder {
       }
     })
 
-    const customTemplateFiles = this.options.build.templates.map(t => t.dst || path.basename(t.src || t))
+    const customTemplateFiles = this.options.build.templates.map(t => t.dst || path.basename(typeof t === 'string' ? t : t.src))
 
     const templatePaths = uniq([
       // Modules & user provided templates
@@ -559,7 +559,7 @@ export default class Builder {
   }
 
   async resolveLoadingIndicator ({ templateFiles }) {
-    if (!this.options.loadingIndicator.name) {
+    if (typeof this.options.loadingIndicator !== 'object' || !this.options.loadingIndicator.name) {
       return
     }
     let indicatorPath = path.resolve(
@@ -671,7 +671,7 @@ export default class Builder {
   }
 
   // TODO: Uncomment when generateConfig enabled again
-  // async generateConfig() {
+  // async generateConfig () {
   //   const config = path.resolve(this.options.buildDir, 'build.config.js')
   //   const options = omit(this.options, Options.unsafeKeys)
   //   await fsExtra.writeFile(
@@ -707,7 +707,7 @@ export default class Builder {
     }
   }
 
-  assignWatcher (key) {
+  assignWatcher (key: string) {
     return (watcher) => {
       if (this.watchers[key]) {
         this.watchers[key].close()
@@ -731,7 +731,7 @@ export default class Builder {
       patterns.push(r(this.options.srcDir, this.options.dir.pages))
     }
 
-    patterns = patterns.map((path, ...args) => upath.normalizeSafe(this.globPathWithExtensions(path), ...args))
+    patterns = patterns.map((path) => upath.normalizeSafe(this.globPathWithExtensions(path)))
 
     const refreshFiles = debounce(() => this.generateRoutesAndFiles(), 200)
 

packages/nuxt3/src/builder/context/template.ts

@@ -3,6 +3,7 @@ import uniqBy from 'lodash/uniqBy'
 import serialize from 'serialize-javascript'
 
 import devalue from '@nuxt/devalue'
+import { NormalizedConfiguration } from 'nuxt/config'
 import { r, wp, wChunk, serializeFunction, isFullStatic } from 'nuxt/utils'
 
 import type Builder from '../builder'
@@ -11,7 +12,7 @@ export default class TemplateContext {
   templateFiles: string[]
   templateVars: any
 
-  constructor (builder: Builder, options) {
+  constructor(builder: Builder, options: NormalizedConfiguration) {
     this.templateFiles = Array.from(builder.template.files)
     this.templateVars = {
       nuxtOptions: options,
@@ -57,7 +58,7 @@ export default class TemplateContext {
     }
   }
 
-  get templateOptions () {
+  get templateOptions() {
     return {
       imports: {
         serialize,

packages/nuxt3/src/builder/ignore.ts

@@ -1,21 +1,29 @@
 import path from 'path'
 import fs from 'fs-extra'
 import ignore from 'ignore'
+import { NormalizedConfiguration } from 'nuxt/config'
 
 type IgnoreInstance = ReturnType<typeof ignore>
 type IgnoreOptions = Parameters<typeof ignore>[0]
 
+interface Options {
+  rootDir: string
+  ignore?: IgnoreInstance
+  ignoreArray?: Array<string | IgnoreInstance>
+  ignoreOptions?: IgnoreOptions
+}
+
 export default class Ignore {
   rootDir: string
   ignore?: IgnoreInstance
-  ignoreArray?: string | string
+  ignoreArray?: Array<string | IgnoreInstance>
   ignoreFile?: string
   ignoreOptions?: IgnoreOptions
 
-  constructor (options) {
-    this.rootDir = options.rootDir
-    this.ignoreOptions = options.ignoreOptions
-    this.ignoreArray = options.ignoreArray
+  constructor ({ ignoreArray, ignoreOptions, rootDir }: Options) {
+    this.rootDir = rootDir
+    this.ignoreOptions = ignoreOptions
+    this.ignoreArray = ignoreArray
     this.addIgnoresRules()
   }
 

packages/nuxt3/src/cli/command.ts

@@ -1,13 +1,13 @@
 
 import path from 'path'
 import consola from 'consola'
-import minimist, { ParsedArgs } from 'minimist'
+import minimist, { Opts as MinimistOptions, ParsedArgs } from 'minimist'
 import Hookable from 'hookable'
 
-import { Nuxt } from 'nuxt/core'
 import { Builder } from 'nuxt/builder'
+import { CliConfiguration } from 'nuxt/config/options'
+import { Nuxt } from 'nuxt/core'
 import { Generator } from 'nuxt/generator'
-import type { Target } from 'nuxt/utils'
 
 import { name, version } from '../../package.json'
 
@@ -26,16 +26,6 @@ export interface Command {
 
 type Hooks = Parameters<Hookable['addHooks']>[0]
 
-interface ExtraOptions {
-  _build?: boolean
-  _cli?: boolean
-  _export?: boolean
-  _generate?: boolean
-  _start?: boolean
-  dev?: boolean
-  server?: boolean
-  target?: Target
-}
 
 export default class NuxtCommand extends Hookable {
   _argv: string[]
@@ -133,7 +123,7 @@ export default class NuxtCommand extends Hookable {
     return this._parsedArgv
   }
 
-  async getNuxtConfig (extraOptions: ExtraOptions = {}) {
+  async getNuxtConfig(extraOptions: Partial<CliConfiguration> = {}) {
     // Flag to indicate nuxt is running with CLI (not programmatic)
     extraOptions._cli = true
 
@@ -154,7 +144,7 @@ export default class NuxtCommand extends Hookable {
     return options
   }
 
-  async getNuxt (options) {
+  async getNuxt (options: CliConfiguration) {
 
     const nuxt = new Nuxt(options)
     await nuxt.ready()
@@ -166,12 +156,12 @@ export default class NuxtCommand extends Hookable {
     return new Builder(nuxt)
   }
 
-  async getGenerator (nuxt) {
+  async getGenerator (nuxt: Nuxt) {
     const builder = await this.getBuilder(nuxt)
     return new Generator(nuxt, builder)
   }
 
-  async setLock (lockRelease) {
+  async setLock (lockRelease?: () => Promise<any>) {
     if (lockRelease) {
       if (this._lockRelease) {
         consola.warn(`A previous unreleased lock was found, this shouldn't happen and is probably an error in 'nuxt ${this.cmd.name}' command. The lock will be removed but be aware of potential strange results`)
@@ -200,7 +190,7 @@ export default class NuxtCommand extends Hookable {
   }
 
   _getMinimistOptions () {
-    const minimistOptions = {
+    const minimistOptions: MinimistOptions = {
       alias: {},
       boolean: [],
       string: [],
@@ -225,7 +215,7 @@ export default class NuxtCommand extends Hookable {
   }
 
   _getHelp () {
-    const options = []
+    const options: [string, string][] = []
     let maxOptionLength = 0
 
     for (const name in this.cmd.options) {

packages/nuxt3/src/cli/options/server.ts

@@ -1,11 +1,16 @@
 import consola from 'consola'
+import type { ParsedArgs} from 'minimist'
+
+import { Configuration } from 'nuxt/config/options'
+
+import NuxtCommand from '../command'
 
 export default {
   port: {
     alias: 'p',
     type: 'string',
     description: 'Port number on which to start the application',
-    prepare (cmd, options, argv) {
+    prepare (_cmd: NuxtCommand, options: Configuration, argv: ParsedArgs) {
       if (argv.port) {
         options.server.port = +argv.port
       }
@@ -15,7 +20,7 @@ export default {
     alias: 'H',
     type: 'string',
     description: 'Hostname on which to start the application',
-    prepare (cmd, options, argv) {
+    prepare (_cmd: NuxtCommand, _options: any, argv: ParsedArgs) {
       if (argv.hostname === '') {
         consola.fatal('Provided hostname argument has no value')
       }

packages/nuxt3/src/config/config/_app.ts

@@ -1,7 +1,72 @@
-export default () => ({
+import type { App } from 'vue'
+import type { MetaInfo, VueMetaOptions } from 'vue-meta'
+
+type Plugin = string | { mode?: 'all' | 'client' | 'server', src: string, ssr?: boolean }
+
+interface AppOptions {
+  css: string[]
+  head: MetaInfo
+  ErrorPage: null | string
+  extendPlugins: null | ((plugins: Plugin[]) => Plugin[])
+  features: {
+    store: boolean
+    layouts: boolean
+    meta: boolean
+    middleware: boolean
+    transitions: boolean
+    deprecations: boolean
+    validate: boolean
+    asyncData: boolean
+    fetch: boolean
+    clientOnline: boolean
+    clientPrefetch: boolean
+    clientUseUrl: boolean
+    componentAliases: boolean
+    componentClientOnly: boolean
+  }
+  fetch: {
+    server: boolean
+    client: boolean
+  }
+  layouts: {}
+  layoutTransition: {
+    name: string
+    mode?: string | 'out-in'
+  }
+  loading: string | false | {
+    color?: string
+    continuous?: boolean
+    css?: boolean
+    duration?: number
+    failedColor?: string
+    height?: string
+    rtl?: boolean
+    throttle?: number
+  }
+  loadingIndicator: string | false | {
+    background?: string
+    color?: string
+    color2?: string
+    name?: string
+  }
+  pageTransition: {
+    name: string
+    mode?: string | 'out-in'
+    appear?: boolean
+    appearClass?: string
+    appearActiveClass?: string
+    appearToClass?: string
+  }
+  plugins: Array<Plugin>
+  vue: {
+    config: Partial<App['config']>
+  }
+  vueMeta: null | VueMetaOptions
+}
+
+export default (): AppOptions => ({
   vue: {
     config: {
-      silent: undefined, // = !dev
       performance: undefined // = dev
     }
   },
@@ -74,3 +139,34 @@ export default () => ({
     componentClientOnly: true
   }
 })
+
+// type NormalizedConfiguration<T extends Record<string, any>> = T & {
+//   pageTransition?: Exclude<T['pageTransition'], string>
+//   layoutTransition?: Exclude<T['layoutTransition'], string>
+//   extensions?: Exclude<T['extensions'], string>
+// }
+
+// export function normalizeAppConfig<O extends Configuration>(options: O): asserts options is NormalizedConfiguration<O> {
+//   (options as NormalizedConfiguration<O>).__normalized__ = true
+
+//   // Normalize options
+//   if (options.loading === true) {
+//     delete options.loading
+//   }
+
+//   if (options.router && typeof options.router.base === 'string') {
+//     (options as NormalizedConfiguration<O>)._routerBaseSpecified = true
+//   }
+
+//   if (typeof options.pageTransition === 'string') {
+//     options.pageTransition = { name: options.pageTransition }
+//   }
+
+//   if (typeof options.layoutTransition === 'string') {
+//     options.layoutTransition = { name: options.layoutTransition }
+//   }
+
+//   if (typeof options.extensions === 'string') {
+//     options.extensions = [options.extensions]
+//   }
+// }

packages/nuxt3/src/config/config/_common.ts

@@ -1,8 +1,133 @@
+import type { WatchOptions as ChokidarWatchOptions } from 'chokidar'
+import type { NextHandleFunction, Server as ConnectServer } from 'connect'
+import type { configHooksT } from 'hookable/types/types'
+import ignore from 'ignore'
 import capitalize from 'lodash/capitalize'
 import env from 'std-env'
-import { TARGETS, MODES } from 'nuxt/utils'
+import type { Configuration as WebpackConfiguration } from 'webpack'
 
-export default () => ({
+import { TARGETS, MODES, Target, Mode } from 'nuxt/utils'
+
+import type { NormalizedConfiguration } from '../options'
+import Hookable from 'hookable'
+
+type IgnoreOptions = Parameters<typeof ignore>[0]
+type IgnoreInstance = ReturnType<typeof ignore>
+
+interface ExtendFunctionContext {
+  isClient: boolean
+  isDev: boolean
+  isLegacy: boolean
+  isModern: boolean
+  isServer: boolean
+  // TODO
+  // loaders: NuxtOptionsLoaders
+}
+
+type ExtendFunction = (config: WebpackConfiguration, ctx: ExtendFunctionContext) => void
+
+interface NuxtHooks extends configHooksT {
+
+  build?: {
+    before?(builder: any, buildOptions: any): void
+    compile?(params: { name: 'client' | 'server', compiler: any }): void
+    compiled?(params: { name: 'client' | 'server', compiler: any, stats: any }): void
+    done?(builder: any): void
+    extendRoutes?(routes: any, resolve: any): void
+    templates?(params: { templateFiles: any, templateVars: any, resolve: any }): void
+  }
+  close?(nuxt: any): void
+  error?(error: Error): void
+  generate?: {
+    before?(generator: any, generateOptions: any): void
+    distCopied?(generator: any): void
+    distRemoved?(generator: any): void
+    done?(generator: any): void
+    extendRoutes?(routes: any): void
+    page?(params: { route: any, path: any, html: any }): void
+    routeCreated?(route: any, path: any, errors: any): void
+    routeFailed?(route: any, errors: any): void
+  }
+  listen?(server: any, params: { host: string, port: number | string }): void
+  modules?: {
+    before?(moduleContainer: any, options: any): void
+    done?(moduleContainer: any): void
+  }
+  ready?(nuxt: any): void
+  render?: {
+    before?(renderer: any, options: any): void
+    done?(renderer: any): void
+    errorMiddleware?(app: ConnectServer): void
+    resourcesLoaded?(resources: any): void
+    route?(url: string, result: any, context: any): void
+    routeContext?(context: any): void
+    routeDone?(url: string, result: any, context: any): void
+    beforeResponse?(url: string, result: any, context: any): void
+    setupMiddleware?(app: ConnectServer): void
+  }
+}
+
+interface ModuleThis {
+  extendBuild(fn: ExtendFunction): void
+  options: NormalizedConfiguration
+  nuxt: any // TBD
+  [key: string]: any // TBD
+}
+
+export type ModuleHandler<T = any> = (this: ModuleThis, moduleOptions: T) => Promise<void> | void
+
+export type NuxtModule = string | ModuleHandler | [string | ModuleHandler, any]
+
+export type ServerMiddleware = string | { path: string, prefix?: boolean, handler: string | NextHandleFunction } | NextHandleFunction
+
+interface CommonConfiguration {
+  _modules: NuxtModule[]
+  _nuxtConfigFile?: string
+  alias: Record<string, string>
+  buildDir: string
+  buildModules: NuxtModule[]
+  createRequire?: (module: NodeJS.Module) => NodeJS.Require
+  debug?: boolean
+  dev: boolean
+  dir: { [key in 'app' | 'assets' | 'layouts' | 'middleware' | 'pages' | 'static' | 'store']: string }
+  editor: undefined
+  env: NodeJS.ProcessEnv
+  extensions: string[]
+  globalName?: string,
+  globals: {
+    id: (globalName: string) => string
+    nuxt: (globalName: string) => string
+    context: (globalName: string) => string
+    pluginPrefix: (globalName: string) => string
+    readyCallback: (globalName: string) => string
+    loadedCallback: (globalName: string) => string
+  }
+  hooks: null | ((hook: Hookable['hook']) => void) | NuxtHooks
+  ignoreOptions?: IgnoreOptions
+  ignorePrefix: string
+  ignore: Array<string | IgnoreInstance>
+  // TODO: remove in Nuxt 3
+  mode: Mode
+  modern?: boolean
+  modules: NuxtModule[]
+  privateRuntimeConfig: Record<string, any> | ((env: NodeJS.ProcessEnv) => Record<string, any>)
+  publicRuntimeConfig: Record<string, any> | ((env: NodeJS.ProcessEnv) => Record<string, any>)
+  serverMiddleware: Array<ServerMiddleware> | Record<string, NextHandleFunction>
+  ssr: boolean
+  target: Target
+  test: boolean
+  srcDir?: string
+  modulesDir: string[]
+  styleExtensions: string[]
+  watch: string[]
+  watchers: {
+    rewatchOnRawEvents?: boolean
+    webpack: WebpackConfiguration['watchOptions']
+    chokidar: ChokidarWatchOptions
+  }
+}
+
+export default (): CommonConfiguration => ({
   // Env
   dev: Boolean(env.dev),
   test: Boolean(env.test),

packages/nuxt3/src/config/config/build.ts

@@ -1,27 +1,261 @@
 import env from 'std-env'
+import type { BundleAnalyzerPlugin } from 'webpack-bundle-analyzer'
+
+import type { TransformOptions, PluginItem } from '@babel/core'
+import type { Options as AutoprefixerOptions } from 'autoprefixer'
+import type { Options as FileLoaderOptions } from 'file-loader'
+import type { Options as HtmlMinifierOptions } from 'html-minifier'
+import type * as Less from 'less'
+import type { Options as SassOptions } from 'node-sass'
+import type { Options as OptimizeCssAssetsWebpackPluginOptions } from 'optimize-css-assets-webpack-plugin'
+import type { Plugin as PostcssPlugin } from 'postcss'
+import type { Options as PugOptions } from 'pug'
+import type { TerserPluginOptions } from 'terser-webpack-plugin'
+import type { VueLoaderOptions } from 'vue-loader'
+import type {
+  Configuration as WebpackConfiguration, WebpackPluginFunction,
+
+
+} from 'webpack'
+import type { Options as WebpackDevMiddlewareOptions } from 'webpack-dev-middleware'
+import type { MiddlewareOptions as WebpackHotMiddlewareOptions, ClientOptions as WebpackHotMiddlewareClientOptions } from 'webpack-hot-middleware'
+
+
+interface WebpackEnv {
+  isClient: boolean
+  isDev: boolean
+  isLegacy: boolean
+  isModern: boolean
+  isServer: boolean
+}
+
+interface BabelPresetEnv {
+  envName: 'client' | 'modern' | 'server'
+}
+interface Warning {
+  message: string
+  name: string
+}
+
+interface BabelOptions extends Pick<TransformOptions, Exclude<keyof TransformOptions, 'presets' | 'plugins'>> {
+  cacheCompression?: boolean
+  cacheDirectory?: boolean
+  cacheIdentifier?: string
+  customize?: string | null
+  presets?: ((env: BabelPresetEnv & WebpackEnv, defaultPreset: [string, object]) => PluginItem[] | void) | PluginItem[] | null
+  plugins?: ((env: BabelPresetEnv & WebpackEnv) => NonNullable<TransformOptions['plugins']>) | TransformOptions['plugins']
+}
+
+type CssLoaderUrlFunction = (url: string, resourcePath: string) => boolean
+type CssLoaderImportFunction = (parsedImport: string, resourcePath: string) => boolean
+type CssLoaderMode = 'global' | 'local'
+interface CssLoaderModulesOptions {
+  context?: string
+  getLocalIdent?: (context: string, localIdentName: string, localName: string, options: CssLoaderModulesOptions) => string
+  hashPrefix?: string
+  localIdentName?: string
+  localIdentRegExp?: string | RegExp
+  mode?: CssLoaderMode
+}
+interface CssLoaderOptions {
+  import?: boolean | CssLoaderImportFunction
+  importLoaders?: number
+  localsConvention?: 'asIs' | 'camelCase' | 'camelCaseOnly' | 'dashes' | 'dashesOnly'
+  modules?: boolean | CssLoaderMode | CssLoaderModulesOptions
+  onlyLocals?: boolean
+  sourceMap?: boolean
+  url?: boolean | CssLoaderUrlFunction
+}
+
+interface UrlLoaderOptions {
+  esModule?: boolean
+  // TODO
+  fallback?: any // WebpackLoader
+  limit?: boolean | number | string
+  mimetype?: string
+}
+
+interface WebpackEnv {
+  isClient: boolean
+  isDev: boolean
+  isLegacy: boolean
+  isModern: boolean
+  isServer: boolean
+}
+
+interface PostcssOrderPresetFunctions {
+  cssnanoLast: (names: string[]) => string[]
+  presetEnvAndCssnanoLast: (names: string[]) => string[]
+  presetEnvLast: (names: string[]) => string[]
+}
+type PostcssOrderPreset = keyof PostcssOrderPresetFunctions
+interface PostcssVariableMap {
+  customMedia: Record<string, string>
+  customProperties: Record<string, string>
+  customSelectors: Record<string, string>
+  environmentVariables?: Record<string, string>
+}
+
+
+interface PostcssConfiguration {
+  order?: PostcssOrderPreset | string[] | ((names: string[], presets: PostcssOrderPresetFunctions) => string[])
+  plugins?: {
+    [key: string]: false | { [key: string]: any }
+  } | ((loader: any) => PostcssPlugin<any>[]) | Array<[string | PostcssPlugin<any>, any] | string | PostcssPlugin<any>>
+  preset?: {
+    autoprefixer?: false | AutoprefixerOptions
+    browsers?: string
+    exportTo?: string | string[] | Partial<PostcssVariableMap> | ((map: PostcssVariableMap) => Partial<PostcssVariableMap>)
+    features?: {
+      [key: string]: boolean | { [key: string]: any }
+    }
+    importFrom?: string | string[] | Partial<PostcssVariableMap> | (() => Partial<PostcssVariableMap>)
+    insertAfter?: { [key: string]: PostcssPlugin<any> }
+    insertBefore?: { [key: string]: PostcssPlugin<any> }
+    preserve?: boolean
+    stage?: 0 | 1 | 2 | 3 | 4 | false
+  }
+}
+
+interface VueStyleOptions {
+  manualInject?: boolean
+  ssrId?: boolean
+  shadowMode?: boolean
+}
+
+interface Loaders {
+  css?: CssLoaderOptions
+  cssModules?: CssLoaderOptions
+  file?: FileLoaderOptions
+  fontUrl?: UrlLoaderOptions
+  imgUrl?: UrlLoaderOptions
+  less?: Less.Options
+  pugPlain?: PugOptions
+  sass?: SassOptions
+  scss?: SassOptions
+  stylus?: any // TBD
+  vue?: VueLoaderOptions
+  vueStyle?: {
+    manualInject?: boolean
+    ssrId?: boolean
+    shadowMode?: boolean
+  }
+}
+
+export interface Template {
+  /**
+   * Source file. Can be absolute or relative.
+   */
+  src: string,
+  /**
+   * Destination file within `.nuxt` filter. This filename should be relative to the project `.nuxt` dir
+   */
+  dst: string,
+  /**
+   * Options are provided to template as `options` key
+   */
+  options?: Record<string, any>
+}
 
 export default () => ({
-  quiet: Boolean(env.ci || env.test),
-  analyze: false,
-  profile: process.argv.includes('--profile'),
-  extractCSS: false,
-  cssSourceMap: undefined,
-  ssr: undefined,
-  parallel: false,
+  /**
+   * @private
+   */
+  _publicPath: '/_nuxt/',
+
+  additionalExtensions: [] as string[],
+  aggressiveCodeRemoval: false,
+  /**
+   * Use [webpack-bundle-analyzer](https://github.com/webpack-contrib/webpack-bundle-analyzer) to let you visualize your bundles and how to optimize them.
+   * @default false
+   */
+  analyze: false as boolean | BundleAnalyzerPlugin.Options,
+  babel: {
+    configFile: false,
+    babelrc: false,
+    cacheDirectory: undefined
+  } as BabelOptions,
+  /**
+   * Enable cache of [terser-webpack-plugin](https://github.com/webpack-contrib/terser-webpack-plugin#options) and [cache-loader](https://github.com/webpack-contrib/cache-loader#cache-loader)
+   * 
+   * ⚠️ Experimental
+   * @default false
+   */
   cache: false,
-  standalone: false,
-  publicPath: '/_nuxt/',
-  serverURLPolyfill: 'url',
+  corejs: undefined as undefined | 'auto' | 2 | 3,
+  crossorigin: undefined as undefined | string,
+  /**
+   * Enables CSS Source Map support.
+   * @default true for dev and `false` for production
+   */
+  cssSourceMap: undefined as undefined | boolean,
+  devMiddleware: {} as WebpackDevMiddlewareOptions,
+  devtools: undefined as undefined | boolean,
+  extend: null as null | ((
+    config: WebpackConfiguration,
+    ctx: {
+      loaders: Loaders
+    } & WebpackEnv
+  ) => void),
+  /**
+   * Enables Common CSS Extraction using Vue Server Renderer guidelines.
+   *
+   * Using [extract-css-chunks-webpack-plugin](https://github.com/faceyspacey/extract-css-chunks-webpack-plugin/) under the hood, all your CSS will be extracted into separate files, usually one per component. This allows caching your CSS and JavaScript separately and is worth a try in case you have a lot of global or shared CSS.
+   * 
+   * @default false
+   */
+  extractCSS: false as boolean | Record<string, any>,
+  /**
+   * Customize bundle filenames.
+   */
   filenames: {
-    // { isDev, isClient, isServer }
-    app: ({ isDev, isModern }) => isDev ? `[name]${isModern ? '.modern' : ''}.js` : `[name].[contenthash:7]${isModern ? '.modern' : ''}.js`,
-    chunk: ({ isDev, isModern }) => isDev ? `[name]${isModern ? '.modern' : ''}.js` : `[name].[contenthash:7]${isModern ? '.modern' : ''}.js`,
-    css: ({ isDev }) => isDev ? '[name].css' : '[name].[contenthash:7].css',
-    img: ({ isDev }) => isDev ? '[path][name].[ext]' : 'img/[name].[contenthash:7].[ext]',
-    font: ({ isDev }) => isDev ? '[path][name].[ext]' : 'fonts/[name].[contenthash:7].[ext]',
-    video: ({ isDev }) => isDev ? '[path][name].[ext]' : 'videos/[name].[contenthash:7].[ext]'
+    app: ({ isDev, isModern }: WebpackEnv) => isDev ? `[name]${isModern ? '.modern' : ''}.js` : `[name].[contenthash:7]${isModern ? '.modern' : ''}.js`,
+    chunk: ({ isDev, isModern }: WebpackEnv) => isDev ? `[name]${isModern ? '.modern' : ''}.js` : `[name].[contenthash:7]${isModern ? '.modern' : ''}.js`,
+    css: ({ isDev }: WebpackEnv) => isDev ? '[name].css' : '[name].[contenthash:7].css',
+    img: ({ isDev }: WebpackEnv) => isDev ? '[path][name].[ext]' : 'img/[name].[contenthash:7].[ext]',
+    font: ({ isDev }: WebpackEnv) => isDev ? '[path][name].[ext]' : 'fonts/[name].[contenthash:7].[ext]',
+    video: ({ isDev }: WebpackEnv) => isDev ? '[path][name].[ext]' : 'videos/[name].[contenthash:7].[ext]'
   },
+  /**
+   * By default, the build process does not scan files inside symlinks. This boolean includes them, thus allowing usage of symlinks inside folders such as the "pages" folder, for example.
+   * @default false
+   */
+  followSymlinks: false,
+  /**
+   * Enables or disables the overlay provided by [FriendlyErrorsWebpackPlugin](https://github.com/nuxt/friendly-errors-webpack-plugin)
+   * @default true
+   */
+  friendlyErrors: true,
+  hardSource: false,
+  hotMiddleware: {} as WebpackHotMiddlewareOptions & { client?: WebpackHotMiddlewareClientOptions },
+  html: {
+    /**
+     * Configuration for the [html-minifier plugin](https://github.com/kangax/html-minifier) used to minify HTML files created during the build process (will be applied for all modes).
+     */
+    minify: {
+      collapseBooleanAttributes: true,
+      decodeEntities: true,
+      minifyCSS: true,
+      minifyJS: true,
+      processConditionalComments: true,
+      removeEmptyAttributes: true,
+      removeRedundantAttributes: true,
+      trimCustomFragments: true,
+      useShortDoctype: true
+    }
+  } as { minify: HtmlMinifierOptions },
+  indicator: {
+    position: 'bottom-right',
+    backgroundColor: '#2E495E',
+    color: '#00C48D'
+  } as boolean | { position: string, backgroundColor: string, color: string },
+  /**
+   * Customize options of Nuxt.js integrated webpack loaders.
+   */
   loaders: {
+    /**
+     * Mor details at https://github.com/webpack-contrib/file-loader#options
+     */
     file: {},
     fontUrl: { limit: 1000 },
     imgUrl: { limit: 1000 },
@@ -47,18 +281,14 @@ export default () => ({
       }
     },
     scss: {},
+    // tODO
     stylus: {},
     vueStyle: {}
-  },
-  styleResources: {},
-  plugins: [],
-  terser: {},
-  hardSource: false,
-  aggressiveCodeRemoval: false,
-  optimizeCSS: undefined,
+  } as Loaders,
+  loadingScreen: {} as Record<string, any> | false,
   optimization: {
     runtimeChunk: 'single',
-    minimize: undefined,
+    minimize: undefined as boolean | undefined,
     minimizer: undefined,
     splitChunks: {
       chunks: 'all',
@@ -69,62 +299,87 @@ export default () => ({
         }
       }
     }
-  },
-  splitChunks: {
-    layouts: false,
-    pages: true,
-    commons: true
-  },
-  babel: {
-    configFile: false,
-    babelrc: false,
-    cacheDirectory: undefined
-  },
-  transpile: [], // Name of NPM packages to be transpiled
+  } as WebpackConfiguration['optimization'],
+  optimizeCSS: undefined as undefined | OptimizeCssAssetsWebpackPluginOptions | boolean,
+  /**
+   * Enable [thread-loader](https://github.com/webpack-contrib/thread-loader#thread-loader) in webpack building
+   * 
+   * ⚠️ Experimental
+   * @default false
+   */
+  parallel: false,
+  plugins: [] as WebpackPluginFunction[],
   postcss: {
     preset: {
       // https://cssdb.org/#staging-process
       stage: 2
     }
-  },
-  html: {
-    minify: {
-      collapseBooleanAttributes: true,
-      decodeEntities: true,
-      minifyCSS: true,
-      minifyJS: true,
-      processConditionalComments: true,
-      removeEmptyAttributes: true,
-      removeRedundantAttributes: true,
-      trimCustomFragments: true,
-      useShortDoctype: true
+  } as string[] | boolean | PostcssConfiguration | (() => PostcssConfiguration),
+  /**
+   * Enable the profiler in [WebpackBar](https://github.com/nuxt/webpackbar#profile)
+   * @default false unless enabled by command line argument `--profile`
+   */
+  profile: process.argv.includes('--profile'),
+  /**
+   * Nuxt.js lets you upload your dist files to your CDN for maximum performances, simply set the `publicPath` to your CDN.
+   * @default '/_nuxt/'
+   * @example
+    ```
+    export default {
+      build: {
+        publicPath: 'https://cdn.nuxtjs.org'
+      }
     }
+    ```
+    Then, when launching nuxt build, upload the content of .nuxt/dist/client directory to your CDN and voilà!
+   */
+  publicPath: '/_nuxt/',
+  /**
+   * Suppresses most of the build output log
+   * @default true when a CI or test environment is detected by [std-env](https://github.com/nuxt-contrib/std-env)
+   */
+  quiet: Boolean(env.ci || env.test),
+  /**
+   * @default 'url'
+   */
+  serverURLPolyfill: 'url',
+  splitChunks: {
+    layouts: false,
+    pages: true,
+    commons: true
   },
-
-  template: undefined,
-  templates: [],
-
-  watch: [],
-  devMiddleware: {},
-  hotMiddleware: {},
-
+  /**
+   * Creates special webpack bundle for SSR renderer. 
+   * @default true for universal mode and `false` for spa mode
+   */
+  ssr: undefined as undefined | boolean,
+  /**
+   * 
+   */
+  standalone: false,
   stats: {
     excludeAssets: [
       /.map$/,
       /index\..+\.html$/,
       /vue-ssr-(client|modern)-manifest.json/
     ]
-  },
-  friendlyErrors: true,
-  additionalExtensions: [],
-  warningIgnoreFilters: [],
+  } as 'none' | false | { excludeAssets: RegExp[] },
+  styleResources: {},
+  template: undefined,
+  /**
+   * Nuxt.js allows you provide your own templates which will be rendered based on Nuxt configuration. This feature is specially useful for using with modules.
+   */
+  templates: [] as Template[],
+  /**
+   * Terser plugin options. Set to `false` to disable this plugin. See https://github.com/webpack-contrib/terser-webpack-plugin 
+   */
+  terser: {} as TerserPluginOptions | boolean,
+  // Name of NPM packages to be transpiled
+  transpile: [] as Array<string | RegExp | ((context: WebpackEnv) => string | RegExp | undefined)>,
+  warningIgnoreFilters: [] as Array<(warn: Warning) => boolean>,
+  /**
+   * You can provide your custom files to watch and regenerate after changes. This feature is specially useful for using with modules.
+   */
+  watch: [] as string[],
 
-  followSymlinks: false,
-
-  loadingScreen: {},
-  indicator: {
-    position: 'bottom-right',
-    backgroundColor: '#2E495E',
-    color: '#00C48D'
-  }
 })

packages/nuxt3/src/config/config/cli.ts

@@ -1,4 +1,11 @@
-export default () => ({
+import { Color } from 'chalk'
+
+export interface CliOptions {
+  badgeMessages: string[]
+  bannerColor: typeof Color
+}
+
+export default (): CliOptions => ({
   badgeMessages: [],
   bannerColor: 'green'
 })

packages/nuxt3/src/config/config/generate.ts

@@ -1,5 +1,33 @@
+import { GlobbyOptions } from 'globby'
 
-export default () => ({
+type GenerateRoute = string | { route: string, payload: any }
+
+type GenerateRoutesFunction = () => (Promise<GenerateRoute[]> | GenerateRoute[])
+type GenerateRoutesFunctionWithCallback = (callback: (err: Error, routes: GenerateRoute[]) => void) => void
+
+export interface GenerateOptions {
+  cache?: false | {
+    ignore?: string[] | Function,
+    globbyOptions?: GlobbyOptions
+  }
+  concurrency: number
+  crawler: boolean
+  devtools?: boolean
+  dir: string
+  exclude: RegExp[]
+  fallback: boolean | string
+  interval: number
+  routes: GenerateRoute[] | GenerateRoutesFunction | GenerateRoutesFunctionWithCallback
+  staticAssets: {
+    base?: string
+    versionBase?: string
+    dir?: string
+    version?: string
+  }
+  subFolders: boolean
+}
+
+export default (): GenerateOptions => ({
   dir: 'dist',
   routes: [],
   exclude: [],

packages/nuxt3/src/config/config/index.ts

@@ -9,16 +9,12 @@ import render from './render'
 import router from './router'
 import server from './server'
 import cli from './cli'
-import generate from './generate'
+import generate, { GenerateOptions } from './generate'
 
 export const defaultNuxtConfigFile = 'nuxt.config'
 
-export function getDefaultNuxtConfig (options = {}) {
-  if (!options.env) {
-    options.env = process.env
-  }
-
-  return {
+export const getDefaultNuxtConfig = () =>
+  ({
     ..._app(),
     ..._common(),
     build: build(),
@@ -26,8 +22,11 @@ export function getDefaultNuxtConfig (options = {}) {
     modes: modes(),
     render: render(),
     router: router(),
-    server: server(options),
+    server: server({ env: process.env }) as ReturnType<typeof server> | boolean,
     cli: cli(),
-    generate: generate()
-  }
-}
+    generate: generate(),
+    export: undefined as undefined | GenerateOptions,
+    telemetry: undefined as undefined | boolean,
+  })
+
+export type DefaultConfiguration = ReturnType<typeof getDefaultNuxtConfig>

packages/nuxt3/src/config/config/modes.ts

@@ -8,7 +8,7 @@ export default () => ({
     render: {
       ssr: true
     }
-  },
+  } as const,
   [MODES.spa]: {
     build: {
       ssr: false
@@ -16,5 +16,5 @@ export default () => ({
     render: {
       ssr: false
     }
-  }
+  } as const
 })

packages/nuxt3/src/config/config/render.ts

@@ -1,6 +1,75 @@
 // TODO: Refactor @nuxt/server related options into `server.js`
+import type { ServerResponse } from 'http'
+import type { Options as EtagOptions } from 'etag'
+import type { IncomingMessage } from 'connect'
+import type { CompressionOptions } from 'compression'
+import type { ServeStaticOptions } from 'serve-static'
+import type { ServerMiddleware } from './_common'
 
-export default () => ({
+interface PreloadFile {
+  asType: 'script' | 'style' | 'font'
+  extension: string
+  file: string
+  fileWithoutQuery: string
+}
+
+type ServePlaceholderHandler = 'default' | 'css' | 'html' | 'js' | 'json' | 'map' | 'plain' | 'image'
+interface ServePlaceholderOptions {
+  handlers?: Record<string, ServePlaceholderHandler | null | false>
+  mimes?: Record<ServePlaceholderHandler, string | false | undefined>
+  noCache?: boolean
+  placeholders?: Record<ServePlaceholderHandler, string | Buffer | false>
+  skipUnknown?: boolean
+  statusCode?: false | number
+}
+
+type CspPolicyName = 'child-src' | 'connect-src' | 'default-src' | 'font-src' | 'frame-src' | 'img-src' | 'manifest-src' | 'media-src' | 'object-src' | 'prefetch-src' | 'script-src' | 'script-src-elem' | 'script-src-attr' | 'style-src' | 'style-src-elem' | 'style-src-attr' | 'worker-src' | 'base-uri' | 'plugin-types' | 'sandbox' | 'form-action' | 'frame-ancestors' | 'navigate-to' | 'report-uri' | 'report-to' | 'block-all-mixed-content' | 'referrer' | 'require-sri-for' | 'trusted-types' | 'upgrade-insecure-requests'
+
+interface RenderOptions {
+  bundleRenderer: {
+    shouldPrefetch: () => boolean
+    shouldPreload: (fileWithoutQuery: string, asType: string) => boolean
+    runInNewContext?: boolean
+  }
+  compressor: CompressionOptions | ServerMiddleware | false
+  crossorigin?: 'anonymous' | 'use-credentials' | ''
+  csp: boolean | {
+    addMeta?: boolean
+    allowedSources?: string[]
+    hashAlgorithm?: string
+    policies?: Record<CspPolicyName, string[]>
+    reportOnly?: boolean
+    unsafeInlineCompatibility?: boolean
+  }
+  dist: ServeStaticOptions
+  etag: false | EtagOptions & {
+    hash?: (html: string) => string
+  }
+  fallback?: {
+    dist?: ServePlaceholderOptions
+    static?: ServePlaceholderOptions
+  }
+  /**
+   * @deprecated
+   */
+  gzip?: CompressionOptions | ServerMiddleware | false
+  http2?: {
+    push?: boolean
+    shouldPush?: boolean | null
+    pushAssets?: null | ((
+      req: IncomingMessage,
+      res: ServerResponse,
+      publicPath: string,
+      preloadFiles: PreloadFile[]
+    ) => string[])
+  }
+  resourceHints: boolean
+  ssr?: boolean
+  ssrLog?: boolean | 'collapsed'
+  static: ServeStaticOptions
+}
+
+export default (): RenderOptions => ({
   bundleRenderer: {
     shouldPrefetch: () => false,
     shouldPreload: (fileWithoutQuery, asType) => ['script', 'style'].includes(asType),
@@ -15,9 +84,7 @@ export default () => ({
     shouldPush: null,
     pushAssets: null
   },
-  static: {
-    prefix: true
-  },
+  static: {},
   compressor: {
     threshold: 0
   },

packages/nuxt3/src/config/config/router.ts

@@ -1,4 +1,36 @@
-export default () => ({
+import { RouteRecordRaw, ScrollBehavior } from 'vue-router'
+
+type UnionToIntersection<T> = (T extends any ? (k: T) => void : never) extends ((k: infer U) => void) ? U : never
+type RouteConfig = UnionToIntersection<RouteRecordRaw>
+
+export interface Route extends Pick<RouteConfig, Exclude<keyof RouteConfig, 'children' | 'component'>> {
+  children?: Route[]
+  chunkName?: string
+  chunkNames?: Record<string, string>
+  component?: RouteConfig['component'] | string
+}
+interface Middleware { }
+
+export interface RouterConfigurationNormalized {
+  base: string
+  extendRoutes?(routes: Route[], resolve: (...pathSegments: string[]) => string): void
+  fallback: boolean
+  linkActiveClass: string | false
+  linkExactActiveClass: string | false
+  linkPrefetchedClass: string | false
+  middleware: Middleware[]
+  mode: 'history' | 'hash'
+  parseQuery: boolean
+  prefetchLinks: boolean
+  prefetchPayloads: boolean
+  routes: Route[]
+  routeNameSplitter: string
+  scrollBehavior: null | ScrollBehavior
+  stringifyQuery: boolean
+  trailingSlash?: boolean
+}
+
+export default (): RouterConfigurationNormalized => ({
   mode: 'history',
   base: '/',
   routes: [],

packages/nuxt3/src/config/config/server.ts

@@ -1,5 +1,19 @@
-export default ({ env = {} } = {}) => ({
-  https: false,
+export interface ServerProcessEnv extends NodeJS.ProcessEnv {
+  NUXT_HOST?: string
+  NUXT_PORT?: string
+  HOST?: string
+  PORT?: string
+  UNIX_SOCKET?: string
+  npm_package_config_nuxt_port?: string
+  npm_package_config_nuxt_host?: string
+  npm_package_config_unix_socket?: string
+}
+
+export default ({ env = {} }: { env?: ServerProcessEnv } = {}) => ({
+  https: false as false | {
+    cert?: string | Buffer
+    key?: string | Buffer
+  },
   port: env.NUXT_PORT ||
     env.PORT ||
     env.npm_package_config_nuxt_port ||
@@ -10,5 +24,5 @@ export default ({ env = {} } = {}) => ({
     'localhost',
   socket: env.UNIX_SOCKET ||
     env.npm_package_config_unix_socket,
-  timing: false
+  timing: false as false | { total: boolean }
 }) 

packages/nuxt3/src/config/index.ts

@@ -1,3 +1,3 @@
 export { defaultNuxtConfigFile, getDefaultNuxtConfig } from './config'
-export { getNuxtConfig } from './options'
+export { getNuxtConfig, Configuration, NormalizedConfiguration } from './options'
 export { loadNuxtConfig } from './load'

packages/nuxt3/src/config/load.ts

@@ -11,10 +11,15 @@ import * as rc from 'rc9'
 
 import { LoadOptions } from 'nuxt/core/load'
 import { defaultNuxtConfigFile } from './config'
+import { CliConfiguration, Configuration } from 'nuxt/config/options'
 
 // @ts-ignore
 const isJest = typeof jest !== 'undefined'
 
+const interopDefault = (obj: any) => {
+  return 'default' in obj ? obj.default : obj
+}
+
 export interface EnvConfig {
   dotenv?: string
   env?: NodeJS.ProcessEnv & { _applied?: boolean }
@@ -31,7 +36,7 @@ export async function loadNuxtConfig ({
 }: LoadOptions = {}) {
   rootDir = path.resolve(rootDir)
 
-  let options = {}
+  let options: CliConfiguration = {}
 
   try {
     configFile = require.resolve(path.resolve(rootDir, configFile))
@@ -66,17 +71,11 @@ export async function loadNuxtConfig ({
     // Clear cache
     clearRequireCache(configFile)
     const _require = createRequire(module)
-    options = _require(configFile) || {}
-    if (options.default) {
-      options = options.default
-    }
+    let _config: Configuration | ((ctx: Record<string, any>) => Promise<Configuration>) = interopDefault(_require(configFile) || {})
 
-    if (typeof options === 'function') {
+    if (typeof _config === 'function') {
       try {
-        options = await options(configContext)
-        if (options.default) {
-          options = options.default
-        }
+        options = interopDefault(await _config(configContext))
       } catch (error) {
         consola.error(error)
         consola.fatal('Error while fetching async configuration')

packages/nuxt3/src/config/options.ts

@@ -1,97 +1,104 @@
 import path from 'path'
 import fs from 'fs'
-import defaultsDeep from 'lodash/defaultsDeep'
+import consola from 'consola'
 import defu from 'defu'
+import destr from 'destr'
+import defaultsDeep from 'lodash/defaultsDeep'
 import pick from 'lodash/pick'
 import uniq from 'lodash/uniq'
-import consola from 'consola'
-import destr from 'destr'
-import { TARGETS, MODES, guardDir, isNonEmptyString, isPureObject, isUrl, getMainModule, urlJoin, getPKG } from 'nuxt/utils'
-import { defaultNuxtConfigFile, getDefaultNuxtConfig } from './config'
 
-export function getNuxtConfig (_options) {
+import { TARGETS, MODES, guardDir, isNonEmptyString, isPureObject, isUrl, getMainModule, urlJoin, getPKG, Target, Mode } from 'nuxt/utils'
+
+import { DefaultConfiguration, defaultNuxtConfigFile, getDefaultNuxtConfig } from './config'
+import { deleteProp, mergeConfigs, setProp, overrideProp, Optional } from './transformers'
+import type { EnvConfig } from 'nuxt/config/load'
+
+interface InputConfiguration {
+  appTemplatePath?: string
+  layoutTransition?: string | DefaultConfiguration['layoutTransition']
+  loading?: true | false | DefaultConfiguration['loading']
+  manifest?: {
+    theme_color?: string
+  }
+  pageTransition?: string | DefaultConfiguration['pageTransition']
+  rootDir?: string
+  store?: boolean
+}
+
+export interface Configuration extends InputConfiguration, Optional<Omit<DefaultConfiguration, keyof InputConfiguration>> { }
+
+export interface CliConfiguration extends Configuration {
+  // cli
+  _build?: boolean
+  _cli?: boolean
+  _export?: boolean
+  _generate?: boolean
+  _start?: boolean
+  _ready?: boolean
+  _legacyGenerate?: boolean
+  _env?: NodeJS.ProcessEnv
+  _envConfig?: EnvConfig
+  _nuxtConfigFiles?: string[]
+}
+
+export function getNuxtConfig(_options: Configuration) {
   // Prevent duplicate calls
-  if (_options.__normalized__) {
+  if ('__normalized__' in _options) {
     return _options
   }
 
+  return normalizeConfig(_options as CliConfiguration)
+}
+
+function normalizeConfig(_options: CliConfiguration) {
   // Clone options to prevent unwanted side-effects
-  const options = Object.assign({}, _options)
-  options.__normalized__ = true
+  const _config: CliConfiguration = Object.assign({}, _options)
+
+  setProp(_config, '__normalized__', true as const)
 
   // Normalize options
-  if (options.loading === true) {
-    delete options.loading
+  if (_config.loading === true) {
+    deleteProp(_config, 'loading')
   }
 
-  if (
-    options.router &&
-    options.router.middleware &&
-    !Array.isArray(options.router.middleware)
-  ) {
-    options.router.middleware = [options.router.middleware]
+  setProp(_config, '_routerBaseSpecified', _config.router && typeof _config.router.base === 'string')
+
+  overrideProp(_config, 'pageTransition', typeof _config.pageTransition === 'string' ? { name: _config.pageTransition } : _config.pageTransition)
+  overrideProp(_config, 'layoutTransition', typeof _config.layoutTransition === 'string' ? { name: _config.layoutTransition } : _config.layoutTransition)
+
+  if (typeof _config.extensions === 'string') {
+    _config.extensions = [_config.extensions]
   }
 
-  if (options.router && typeof options.router.base === 'string') {
-    options._routerBaseSpecified = true
-  }
-
-  // TODO: Remove for Nuxt 3
-  // router.scrollBehavior -> app/router.scrollBehavior.js
-  if (options.router && typeof options.router.scrollBehavior !== 'undefined') {
-    consola.warn('`router.scrollBehavior` property is deprecated in favor of using `~/app/router.scrollBehavior.js` file, learn more: https://nuxtjs.org/api/configuration-router#scrollbehavior')
-  }
-
-  // TODO: Remove for Nuxt 3
-  // transition -> pageTransition
-  if (typeof options.transition !== 'undefined') {
-    consola.warn('`transition` property is deprecated in favor of `pageTransition` and will be removed in Nuxt 3')
-    options.pageTransition = options.transition
-    delete options.transition
-  }
-
-  if (typeof options.pageTransition === 'string') {
-    options.pageTransition = { name: options.pageTransition }
-  }
-
-  if (typeof options.layoutTransition === 'string') {
-    options.layoutTransition = { name: options.layoutTransition }
-  }
-
-  if (typeof options.extensions === 'string') {
-    options.extensions = [options.extensions]
-  }
-
-  options.globalName = (isNonEmptyString(options.globalName) && /^[a-zA-Z]+$/.test(options.globalName))
-    ? options.globalName.toLowerCase()
-    // use `` for preventing replacing to nuxt-edge
-    : 'nuxt'
+  overrideProp(_config, 'globalName',
+    (isNonEmptyString(_config.globalName) && /^[a-zA-Z]+$/.test(_config.globalName))
+      ? _config.globalName.toLowerCase()
+      // use `` for preventing replacing to nuxt-edge
+      : 'nuxt'
+  )
 
   // Resolve rootDir
-  options.rootDir = isNonEmptyString(options.rootDir) ? path.resolve(options.rootDir) : process.cwd()
+  overrideProp(_config, 'rootDir',
+    isNonEmptyString(_config.rootDir) ? path.resolve(_config.rootDir) : process.cwd()
+  )
 
   // Apply defaults by ${buildDir}/dist/build.config.js
   // TODO: Unsafe operation.
-  // const buildDir = options.buildDir || defaults.buildDir
-  // const buildConfig = resolve(options.rootDir, buildDir, 'build.config.js')
+  // const buildDir = _config.buildDir || defaults.buildDir
+  // const buildConfig = resolve(_config.rootDir, buildDir, 'build.config.js')
   // if (existsSync(buildConfig)) {
-  //   defaultsDeep(options, require(buildConfig))
+  //   defaultsDeep(_config, require(buildConfig))
   // }
 
-  // Apply defaults
-  const nuxtConfig = getDefaultNuxtConfig()
-
-  nuxtConfig.build._publicPath = nuxtConfig.build.publicPath
-
   // Fall back to default if publicPath is falsy
-  if (options.build && !options.build.publicPath) {
-    options.build.publicPath = undefined
+  if (_config.build && !_config.build.publicPath) {
+    _config.build.publicPath = undefined
   }
 
-  defaultsDeep(options, nuxtConfig)
+  // Apply defaults
+  const options = mergeConfigs(_config, getDefaultNuxtConfig())
 
   // Target
-  options.target = options.target || 'server'
   if (!Object.values(TARGETS).includes(options.target)) {
     consola.warn(`Unknown target: ${options.target}. Falling back to server`)
     options.target = 'server'
@@ -127,16 +134,16 @@ export function getNuxtConfig (_options) {
   const hasGenerateDir = isNonEmptyString(options.generate.dir)
 
   // Resolve srcDir
-  options.srcDir = hasSrcDir
+  overrideProp(options, 'srcDir', hasSrcDir
     ? path.resolve(options.rootDir, options.srcDir)
-    : options.rootDir
+    : options.rootDir)
 
   // Resolve buildDir
-  options.buildDir = path.resolve(options.rootDir, options.buildDir)
+  overrideProp(options, 'buildDir', path.resolve(options.rootDir, options.buildDir))
 
   // Aliases
   const { rootDir, srcDir, dir: { assets: assetsDir, static: staticDir } } = options
-  options.alias = {
+  overrideProp(options, 'alias', {
     '~~': rootDir,
     '@@': rootDir,
     '~': srcDir,
@@ -144,18 +151,14 @@ export function getNuxtConfig (_options) {
     [assetsDir]: path.join(srcDir, assetsDir),
     [staticDir]: path.join(srcDir, staticDir),
     ...options.alias
-  }
+  })
 
   // Default value for _nuxtConfigFile
-  if (!options._nuxtConfigFile) {
-    options._nuxtConfigFile = path.resolve(options.rootDir, `${defaultNuxtConfigFile}.js`)
-  }
+  overrideProp(options, '_nuxtConfigFile', options._nuxtConfigFile || path.resolve(options.rootDir, `${defaultNuxtConfigFile}.js`))
 
-  if (!options._nuxtConfigFiles) {
-    options._nuxtConfigFiles = [
-      options._nuxtConfigFile
-    ]
-  }
+  setProp(options, '_nuxtConfigFiles', (options as any)._nuxtConfigFiles || [
+    options._nuxtConfigFile
+  ])
 
   // Watch for config file changes
   options.watch.push(...options._nuxtConfigFiles)
@@ -190,9 +193,9 @@ export function getNuxtConfig (_options) {
 
   const mandatoryExtensions = ['js', 'mjs']
 
-  options.extensions = mandatoryExtensions
+  overrideProp(options, 'extensions', mandatoryExtensions
     .filter(ext => !options.extensions.includes(ext))
-    .concat(options.extensions)
+    .concat(options.extensions))
 
   // If app.html is defined, set the template path to the user template
   if (options.appTemplatePath === undefined) {
@@ -204,8 +207,8 @@ export function getNuxtConfig (_options) {
     options.appTemplatePath = path.resolve(options.srcDir, options.appTemplatePath)
   }
 
-  options.build.publicPath = options.build.publicPath.replace(/([^/])$/, '$1/')
-  options.build._publicPath = options.build._publicPath.replace(/([^/])$/, '$1/')
+  overrideProp(options.build, 'publicPath', options.build.publicPath.replace(/([^/])$/, '$1/'))
+  overrideProp(options.build, '_publicPath', options.build._publicPath.replace(/([^/])$/, '$1/'))
 
   // Ignore publicPath on dev
   if (options.dev && isUrl(options.build.publicPath)) {
@@ -233,7 +236,7 @@ export function getNuxtConfig (_options) {
     options.loadingIndicator = Object.assign(
       {
         name: 'default',
-        color: (options.loading && options.loading.color) || '#D3D3D3',
+        color: (options.loading && typeof options.loading !== 'string' && typeof options.loading !== 'boolean' && options.loading.color) || '#D3D3D3',
         color2: '#F5F5F5',
         background: (options.manifest && options.manifest.theme_color) || 'white',
         dev: options.dev,
@@ -244,15 +247,13 @@ export function getNuxtConfig (_options) {
   }
 
   // Debug errors
-  if (options.debug === undefined) {
-    options.debug = options.dev
-  }
+  overrideProp(options, 'debug', options.debug ?? options.dev)
 
   // Validate that etag.hash is a function, if not unset it
   if (options.render.etag) {
     const { hash } = options.render.etag
     if (hash) {
-      const isFn = typeof hash === 'function'
+      const isFn = hash instanceof Function
       if (!isFn) {
         options.render.etag.hash = undefined
 
@@ -273,64 +274,26 @@ export function getNuxtConfig (_options) {
       unsafeInlineCompatibility: false,
       reportOnly: options.debug
     })
-
-    // TODO: Remove this if statement in Nuxt 3, we will stop supporting this typo (more on: https://github.com/nuxt/nuxt.js/pull/6583)
-    if (options.render.csp.unsafeInlineCompatiblity) {
-      consola.warn('Using `unsafeInlineCompatiblity` is deprecated and will be removed in Nuxt 3. Use `unsafeInlineCompatibility` instead.')
-      options.render.csp.unsafeInlineCompatibility = options.render.csp.unsafeInlineCompatiblity
-      delete options.render.csp.unsafeInlineCompatiblity
-    }
   }
 
   // cssSourceMap
-  if (options.build.cssSourceMap === undefined) {
-    options.build.cssSourceMap = options.dev
-  }
+  overrideProp(options.build, 'cssSourceMap', options.build.cssSourceMap ?? options.dev)
 
-  const babelConfig = options.build.babel
   // babel cacheDirectory
-  if (babelConfig.cacheDirectory === undefined) {
-    babelConfig.cacheDirectory = options.dev
-  }
-
-  // TODO: remove this warn in Nuxt 3
-  if (Array.isArray(babelConfig.presets)) {
-    const warnPreset = (presetName) => {
-      const oldPreset = '@nuxtjs/babel-preset-app'
-      const newPreset = '@nuxt/babel-preset-app'
-      if (presetName.includes(oldPreset)) {
-        presetName = presetName.replace(oldPreset, newPreset)
-        consola.warn('@nuxtjs/babel-preset-app has been deprecated, please use @nuxt/babel-preset-app.')
-      }
-      return presetName
-    }
-    babelConfig.presets = babelConfig.presets.map((preset) => {
-      const hasOptions = Array.isArray(preset)
-      if (hasOptions) {
-        preset[0] = warnPreset(preset[0])
-      } else if (typeof preset === 'string') {
-        preset = warnPreset(preset)
-      }
-      return preset
-    })
-  }
+  const babelConfig = options.build.babel
+  overrideProp(options.build.babel, 'cacheDirectory', babelConfig.cacheDirectory ?? options.dev)
 
   // Vue config
   const vueConfig = options.vue.config
 
-  if (vueConfig.silent === undefined) {
-    vueConfig.silent = !options.dev
-  }
-  if (vueConfig.performance === undefined) {
-    vueConfig.performance = options.dev
-  }
+  overrideProp(options.vue.config, 'performance', vueConfig.performance !== undefined ? vueConfig.performance : options.dev)
 
   // merge custom env with variables
   const eligibleEnvVariables = pick(process.env, Object.keys(process.env).filter(k => k.startsWith('NUXT_ENV_')))
-  Object.assign(options.env, eligibleEnvVariables)
+  overrideProp(options, 'env', Object.assign(options.env, eligibleEnvVariables))
 
   // Normalize ignore
-  options.ignore = options.ignore ? [].concat(options.ignore) : []
+  overrideProp(options, 'ignore', options.ignore ? Array.from(options.ignore) : [])
 
   // Append ignorePrefix glob to ignore
   if (typeof options.ignorePrefix === 'string') {
@@ -349,24 +312,23 @@ export function getNuxtConfig (_options) {
     options.pageTransition.appear = true
   }
 
-  options.render.ssrLog = options.dev
+  overrideProp(options.render, 'ssrLog', options.dev
     ? options.render.ssrLog === undefined || options.render.ssrLog
-    : false
+    : false)
 
   // We assume the SPA fallback path is 404.html (for GitHub Pages, Surge, etc.)
-  if (options.generate.fallback === true) {
-    options.generate.fallback = '404.html'
-  }
+  overrideProp(options.generate, 'fallback', options.generate.fallback === true ? '404.html' : options.generate.fallback)
 
   if (options.build.stats === 'none' || options.build.quiet === true) {
     options.build.stats = false
   }
 
-  // Vendor backward compatibility with nuxt 1.x
-  if (typeof options.build.vendor !== 'undefined') {
-    delete options.build.vendor
-    consola.warn('vendor has been deprecated due to webpack4 optimization')
-  }
+  // @pi0 - surely this can go
+  // // Vendor backward compatibility with nuxt 1.x
+  // if (typeof options.build.vendor !== 'undefined') {
+  //   delete options.build.vendor
+  //   consola.warn('vendor has been deprecated due to webpack4 optimization')
+  // }
 
   // Disable CSS extraction due to incompatibility with thread-loader
   if (options.build.extractCSS && options.build.parallel) {
@@ -375,17 +337,10 @@ export function getNuxtConfig (_options) {
   }
 
   // build.extractCSS.allChunks has no effect
-  if (typeof options.build.extractCSS.allChunks !== 'undefined') {
+  if (typeof options.build.extractCSS !== 'boolean' && typeof options.build.extractCSS.allChunks !== 'undefined') {
     consola.warn('build.extractCSS.allChunks has no effect from v2.0.0. Please use build.optimization.splitChunks settings instead.')
   }
 
-  // devModules has been renamed to buildModules
-  if (typeof options.devModules !== 'undefined') {
-    consola.warn('`devModules` has been renamed to `buildModules` and will be removed in Nuxt 3.')
-    options.buildModules.push(...options.devModules)
-    delete options.devModules
-  }
-
   // Enable minimize for production builds
   if (options.build.optimization.minimize === undefined) {
     options.build.optimization.minimize = !options.dev
@@ -397,11 +352,11 @@ export function getNuxtConfig (_options) {
   }
 
   const { loaders } = options.build
-  const vueLoader = loaders.vue
-  if (vueLoader.productionMode === undefined) {
-    vueLoader.productionMode = !options.dev
-  }
-  const styleLoaders = [
+  // const vueLoader = loaders.vue
+  // if (vueLoader.productionMode === undefined) {
+  //   vueLoader.productionMode = !options.dev
+  // }
+  const styleLoaders: Array<keyof typeof loaders> = [
     'css', 'cssModules', 'less',
     'sass', 'scss', 'stylus', 'vueStyle'
   ]
@@ -412,7 +367,7 @@ export function getNuxtConfig (_options) {
     }
   }
 
-  options.build.transpile = [].concat(options.build.transpile || [])
+  overrideProp(options.build, 'transpile', Array.from(options.build.transpile || []))
 
   if (options.build.quiet === true) {
     consola.level = 0
@@ -420,32 +375,22 @@ export function getNuxtConfig (_options) {
 
   // Use runInNewContext for dev mode by default
   const { bundleRenderer } = options.render
-  if (typeof bundleRenderer.runInNewContext === 'undefined') {
-    bundleRenderer.runInNewContext = options.dev
+  overrideProp(options.render.bundleRenderer, 'runInNewContext', bundleRenderer.runInNewContext ?? options.dev)
+
+  // const { timing } = options.server
+  if (options.server && typeof options.server !== 'boolean' && options.server.timing) {
+    overrideProp(options.server, 'timing', { total: true, ...options.server.timing })
   }
 
-  // TODO: Remove this if statement in Nuxt 3
-  if (options.build.crossorigin) {
-    consola.warn('Using `build.crossorigin` is deprecated and will be removed in Nuxt 3. Please use `render.crossorigin` instead.')
-    options.render.crossorigin = options.build.crossorigin
-    delete options.build.crossorigin
-  }
 
-  const { timing } = options.server
-  if (timing) {
-    options.server.timing = { total: true, ...timing }
-  }
-
-  if (isPureObject(options.serverMiddleware)) {
-    options.serverMiddleware = Object.entries(options.serverMiddleware)
-      .map(([path, handler]) => ({ path, handler }))
-  }
+  overrideProp(options, 'serverMiddleware', Array.isArray(options.serverMiddleware) ? options.serverMiddleware : Object.entries(options.serverMiddleware)
+    .map(([path, handler]) => ({ path, handler }))
+  )
 
   // Generate staticAssets
   const { staticAssets } = options.generate
-  if (!staticAssets.version) {
-    staticAssets.version = String(Math.round(Date.now() / 1000))
-  }
+  overrideProp(options.generate.staticAssets, 'version', options.generate.staticAssets.version || String(Math.round(Date.now() / 1000)))
+
   if (!staticAssets.base) {
     const publicPath = isUrl(options.build.publicPath) ? '' : options.build.publicPath // "/_nuxt" or custom CDN URL
     staticAssets.base = urlJoin(publicPath, staticAssets.dir)
@@ -492,3 +437,5 @@ export function getNuxtConfig (_options) {
 
   return options
 }
+
+export type NormalizedConfiguration = ReturnType<typeof normalizeConfig>

packages/nuxt3/src/config/transformers.ts

@@ -0,0 +1,38 @@
+import { defaultsDeep } from 'lodash'
+
+export type Optional<T> = {
+    -readonly [K in keyof T]?: T[K] extends Function ? T[K] : T[K] extends RegExp ? T[K] : T[K] extends Promise<any> ? T[K] : T[K] extends Array<infer R> ? Array<R> : Optional<T[K]>
+}
+
+export function setProp<O extends Record<string, any>, K extends string, V>(obj: O, key: K, value: V): asserts obj is O & { [key in K]: V } {
+    (obj as { [key in K]: V })[key] = value
+}
+
+type Override<O extends Record<string, any>, K extends keyof O, V> = K extends Array<infer A> ? {
+    [P in keyof O]: K extends P ? O[P] extends Array<infer T> ? Array<A & T> : K | O[P] : O[P]
+} : O & { [key in K]: V }
+
+export function overrideProp<O extends Record<string, any>, K extends keyof O, V>(obj: O, key: K, value: V): asserts obj is Override<O, K, V> {
+    (obj as { [key in K]: V })[key] = value
+}
+
+export function deleteProp<O extends Record<string, any>, K extends string>(obj: O, key: K): asserts obj is Exclude<O, K> {
+    delete obj[key]
+}
+
+type MergeArrays<S, T> = S extends Array<infer A1> ? T extends Array<infer A2> ? Array<A1 | A2> : T | Array<A1> : T | S
+type MergeObjects<S extends Record<string, any>, T extends Record<string, any>> = Omit<S & T, keyof S & keyof T> & {
+    -readonly [K in keyof S & keyof T]: Merge<S[K], T[K]>
+}
+type Merge<S, T> = S extends Array<any> ? MergeArrays<S, T> : S extends Function ? S | T : S extends RegExp ? S | T : S extends Promise<any> ? S | T : T extends Function ? S | T : S extends Record<string, any> ? T extends Record<string, any> ? MergeObjects<S, T> : S | T : MergeArrays<S, T>
+
+// let b: Merged<{ test: string, another: number[] }, { third: () => void, another: string[] }> = {} as any
+// b.another
+// let c = b
+// c.
+
+// T extends Array<infer A> ? Array<Merged<A, S>> : T
+
+export function mergeConfigs<Dest extends Record<string, any>, Source extends Record<string, any>>(dest: Dest, source: Source): Merge<Dest, Source> {
+    return defaultsDeep(dest, source)
+}

packages/nuxt3/src/core/load.ts

@@ -16,8 +16,8 @@ export interface LoadOptions {
   rootDir?: string
   envConfig?: EnvConfig
   configFile?: string
-  configContext?: {}
-  configOverrides?: {},
+  configContext?: Record<string, any>,
+  configOverrides?: Record<string, any>,
   createRequire?: (module: NodeJS.Module) => NodeJS.Require
 }
 

packages/nuxt3/src/core/module.ts

@@ -3,26 +3,31 @@ import fs from 'fs'
 import hash from 'hash-sum'
 import consola from 'consola'
 
-import { chainFn, sequence } from 'nuxt/utils'
+import type { NormalizedConfiguration } from 'nuxt/config'
+import { chainFn, Mode, sequence } from 'nuxt/utils'
 
 import Nuxt from './nuxt'
+import type { NuxtModule, ModuleHandler } from 'nuxt/config/config/_common'
 
-interface Module {
+interface TemplateInput {
+  filename?: string
+  fileName?: string
+  options?: Record<string, any>
   src: string
-  options: Record<string, any>
-  handler: () => any
-}
-
-interface Template {
-
+  ssr?: boolean
+  mode?: 'all' | 'server' | 'client'
 }
 
 export default class ModuleContainer {
   nuxt: Nuxt
   options: Nuxt['options']
-  requiredModules: Record<string, Module>
+  requiredModules: Record<string, {
+    src: string
+    options: Record<string, any>
+    handler: ModuleHandler
+  }>
 
-  constructor (nuxt: Nuxt) {
+  constructor(nuxt: Nuxt) {
     this.nuxt = nuxt
     this.options = nuxt.options
     this.requiredModules = {}
@@ -35,7 +40,7 @@ export default class ModuleContainer {
     }
   }
 
-  async ready () {
+  async ready() {
     // Call before hook
     await this.nuxt.callHook('modules:before', this, this.options.modules)
 
@@ -54,17 +59,17 @@ export default class ModuleContainer {
     await this.nuxt.callHook('modules:done', this)
   }
 
-  addVendor () {
+  addVendor() {
     consola.warn('addVendor has been deprecated due to webpack4 optimization')
   }
 
-  addTemplate (template) {
+  addTemplate(template: TemplateInput | string) {
     if (!template) {
       throw new Error('Invalid template: ' + JSON.stringify(template))
     }
 
     // Validate & parse source
-    const src = template.src || template
+    const src = typeof template === 'string' ? template : template.src
     const srcPath = path.parse(src)
 
     if (typeof src !== 'string' || !fs.existsSync(src)) {
@@ -72,14 +77,14 @@ export default class ModuleContainer {
     }
 
     // Mostly for DX, some people prefers `filename` vs `fileName`
-    const fileName = template.fileName || template.filename
+    const fileName = typeof template === 'string' ? '' : template.fileName || template.filename
     // Generate unique and human readable dst filename if not provided
     const dst = fileName || `${path.basename(srcPath.dir)}.${srcPath.name}.${hash(src)}${srcPath.ext}`
     // Add to templates list
     const templateObj = {
       src,
       dst,
-      options: template.options
+      options: typeof template === 'string' ? undefined : template.options
     }
 
     this.options.build.templates.push(templateObj)
@@ -87,7 +92,7 @@ export default class ModuleContainer {
     return templateObj
   }
 
-  addPlugin (template) {
+  addPlugin(template: TemplateInput) {
     const { dst } = this.addTemplate(template)
 
     // Add to nuxt plugins
@@ -99,7 +104,7 @@ export default class ModuleContainer {
     })
   }
 
-  addLayout (template, name: string) {
+  addLayout(template: TemplateInput, name: string) {
     const { dst, src } = this.addTemplate(template)
     const layoutName = name || path.parse(src).name
     const layout = this.options.layouts[layoutName]
@@ -117,34 +122,34 @@ export default class ModuleContainer {
     }
   }
 
-  addErrorLayout (dst: string) {
+  addErrorLayout(dst: string) {
     const relativeBuildDir = path.relative(this.options.rootDir, this.options.buildDir)
     this.options.ErrorPage = `~/${relativeBuildDir}/${dst}`
   }
 
-  addServerMiddleware (middleware) {
+  addServerMiddleware(middleware: NormalizedConfiguration['serverMiddleware'][number]) {
     this.options.serverMiddleware.push(middleware)
   }
 
-  extendBuild (fn) {
+  extendBuild(fn: NormalizedConfiguration['build']['extend']) {
     this.options.build.extend = chainFn(this.options.build.extend, fn)
   }
 
-  extendRoutes (fn) {
+  extendRoutes(fn: NormalizedConfiguration['router']['extendRoutes']) {
     this.options.router.extendRoutes = chainFn(
       this.options.router.extendRoutes,
       fn
     )
   }
 
-  requireModule (moduleOpts: Module) {
+  requireModule(moduleOpts: NuxtModule) {
     return this.addModule(moduleOpts)
   }
 
-  async addModule (moduleOpts) {
-    let src
+  async addModule(moduleOpts: NuxtModule) {
+    let src: string | ModuleHandler
     let options: Record<string, any>
-    let handler
+    let handler: ModuleHandler | ModuleHandler & { meta: { name: string } }
 
     // Type 1: String or Function
     if (typeof moduleOpts === 'string' || typeof moduleOpts === 'function') {
@@ -168,7 +173,7 @@ export default class ModuleContainer {
     }
 
     // Resolve handler
-    if (!handler) {
+    if (!handler && typeof src === 'string') {
       try {
         handler = this.nuxt.resolver.requireModule(src, { useESM: true })
       } catch (error) {
@@ -207,18 +212,20 @@ export default class ModuleContainer {
     }
 
     // Ensure module is required once
-    const metaKey = handler.meta && handler.meta.name
-    const key = metaKey || src
-    if (typeof key === 'string') {
-      if (this.requiredModules[key]) {
-        if (!metaKey) {
-          // TODO: Skip with nuxt3
-          consola.warn('Modules should be only specified once:', key)
-        } else {
-          return
+    if ('meta' in handler && typeof src === 'string') {
+      const metaKey = handler.meta && handler.meta.name
+      const key = metaKey || src
+      if (typeof key === 'string') {
+        if (this.requiredModules[key]) {
+          if (!metaKey) {
+            // TODO: Skip with nuxt3
+            consola.warn('Modules should be only specified once:', key)
+          } else {
+            return
+          }
         }
+        this.requiredModules[key] = { src, options, handler: handler as ModuleHandler }
       }
-      this.requiredModules[key] = { src, options, handler }
     }
 
     // Default module options to empty object

packages/nuxt3/src/core/nuxt.ts

@@ -4,7 +4,7 @@ import consola from 'consola'
 import Hookable from 'hookable'
 
 import { defineAlias } from 'nuxt/utils'
-import { getNuxtConfig } from 'nuxt/config'
+import { getNuxtConfig, Configuration, NormalizedConfiguration } from 'nuxt/config'
 import { Server } from 'nuxt/server'
 
 import { version } from '../../package.json'
@@ -12,11 +12,15 @@ import { version } from '../../package.json'
 import ModuleContainer from './module'
 import Resolver from './resolver'
 
+declare global {
+  var __NUXT_DEV__: boolean
+}
+
 export default class Nuxt extends Hookable {
   _ready?: Promise<this>
   _initCalled?: boolean
 
-  options: any
+  options: NormalizedConfiguration
   resolver: Resolver
   moduleContainer: ModuleContainer
   server?: Server
@@ -24,7 +28,7 @@ export default class Nuxt extends Hookable {
   render?: Server['app']
   showReady?: () => void
 
-  constructor (options = {}) {
+  constructor(options: Configuration = {}) {
     super(consola)
 
     // Assign options and apply defaults
@@ -66,28 +70,28 @@ export default class Nuxt extends Hookable {
     }
   }
 
-  static get version () {
+  static get version() {
     return `v${version}` + (global.__NUXT_DEV__ ? '-development' : '')
   }
 
-  ready () {
+  ready() {
     if (!this._ready) {
       this._ready = this._init()
     }
     return this._ready
   }
 
-  async _init () {
+  async _init() {
     if (this._initCalled) {
       return this
     }
     this._initCalled = true
 
     // Add hooks
-    if (isPlainObject(this.options.hooks)) {
-      this.addHooks(this.options.hooks)
-    } else if (typeof this.options.hooks === 'function') {
+    if (this.options.hooks instanceof Function) {
       this.options.hooks(this.hook)
+    } else if (isPlainObject(this.options.hooks)) {
+      this.addHooks(this.options.hooks)
     }
 
     // Await for modules
@@ -104,7 +108,7 @@ export default class Nuxt extends Hookable {
     return this
   }
 
-  _initServer () {
+  _initServer() {
     if (this.server) {
       return
     }
@@ -114,14 +118,11 @@ export default class Nuxt extends Hookable {
     defineAlias(this, this.server, ['renderRoute', 'renderAndGetWindow', 'listen'])
   }
 
-  async close (callback?: () => any | Promise<any>) {
+  async close(callback?: () => any | Promise<any>) {
     await this.callHook('close', this)
 
     if (typeof callback === 'function') {
       await callback()
     }
-
-    // Deleting as no longer exists on `hookable`
-    // this.clearHooks()
   }
 }

packages/nuxt3/src/generator/generator.ts

@@ -31,7 +31,7 @@ export default class Generator {
   routes: Array<{ route: string } & Record<string, any>>
   generatedRoutes: Set<string>
 
-  constructor (nuxt: Nuxt, builder?: Builder) {
+  constructor(nuxt: Nuxt, builder?: Builder) {
     this.nuxt = nuxt
     this.options = nuxt.options
     this.builder = builder
@@ -53,7 +53,7 @@ export default class Generator {
     }
   }
 
-  async generate ({ build = true, init = true } = {}) {
+  async generate({ build = true, init = true } = {}) {
     consola.debug('Initializing generator...')
     await this.initiate({ build, init })
 
@@ -80,7 +80,7 @@ export default class Generator {
     return { errors }
   }
 
-  async initiate ({ build = true, init = true } = {}) {
+  async initiate({ build = true, init = true } = {}) {
     // Wait for nuxt be ready
     await this.nuxt.ready()
 
@@ -119,7 +119,7 @@ export default class Generator {
     }
   }
 
-  async initRoutes (...args) {
+  async initRoutes(...args) {
     // Resolve config.generate.routes promises before generating the routes
     let generateRoutes = []
     if (this.options.router.mode !== 'hash') {
@@ -150,7 +150,7 @@ export default class Generator {
     return routes
   }
 
-  shouldGenerateRoute (route) {
+  shouldGenerateRoute(route) {
     return this.options.generate.exclude.every((regex) => {
       if (typeof regex === 'string') {
         return regex !== route
@@ -159,7 +159,7 @@ export default class Generator {
     })
   }
 
-  getBuildConfig () {
+  getBuildConfig() {
     try {
       return require(path.join(this.options.buildDir, 'nuxt/config.json'))
     } catch (err) {
@@ -167,11 +167,11 @@ export default class Generator {
     }
   }
 
-  getAppRoutes () {
+  getAppRoutes() {
     return require(path.join(this.options.buildDir, 'routes.json'))
   }
 
-  async generateRoutes (routes) {
+  async generateRoutes(routes) {
     const errors = []
 
     this.routes = []
@@ -204,7 +204,7 @@ export default class Generator {
     return errors
   }
 
-  _formatErrors (errors) {
+  _formatErrors(errors) {
     return errors
       .map(({ type, route, error }) => {
         const isHandled = type === 'handled'
@@ -223,7 +223,7 @@ export default class Generator {
       .join('\n')
   }
 
-  async afterGenerate () {
+  async afterGenerate() {
     const { fallback } = this.options.generate
 
     // Disable SPA fallback if value isn't a non-empty string
@@ -255,7 +255,7 @@ export default class Generator {
     consola.success('Client-side fallback created: `' + fallback + '`')
   }
 
-  async initDist () {
+  async initDist() {
     // Clean destination folder
     await fsExtra.emptyDir(this.distPath)
 
@@ -283,7 +283,7 @@ export default class Generator {
     await this.nuxt.callHook('export:distCopied', this)
   }
 
-  decorateWithPayloads (routes, generateRoutes) {
+  decorateWithPayloads(routes, generateRoutes) {
     const routeMap = {}
     // Fill routeMap for known routes
     routes.forEach((route) => {
@@ -301,7 +301,7 @@ export default class Generator {
     return Object.values(routeMap)
   }
 
-  async generateRoute ({ route, payload = {}, errors = [] }) {
+  async generateRoute({ route, payload = {}, errors = [] }) {
     let html
     const pageErrors = []
 
@@ -320,7 +320,8 @@ export default class Generator {
     try {
       const renderContext = {
         payload,
-        staticAssetsBase: this.staticAssetsBase
+        staticAssetsBase: this.staticAssetsBase,
+        staticAssets: undefined
       }
       const res = await this.nuxt.server.renderRoute(route, renderContext)
       html = res.html
@@ -377,7 +378,7 @@ export default class Generator {
       pageErrors.push({ type: 'unhandled', route, error: minifyErr })
     }
 
-    let fileName
+    let fileName: string
 
     if (this.options.generate.subFolders) {
       fileName = path.join(route, path.sep, 'index.html') // /about -> /about/index.html
@@ -414,16 +415,8 @@ export default class Generator {
     return true
   }
 
-  minifyHtml (html) {
-    let minificationOptions = this.options.build.html.minify
-
-    // Legacy: Override minification options with generate.minify if present
-    // TODO: Remove in Nuxt version 3
-    if (typeof this.options.generate.minify !== 'undefined') {
-      minificationOptions = this.options.generate.minify
-      consola.warn('generate.minify has been deprecated and will be removed in the next major version.' +
-        ' Use build.html.minify instead!')
-    }
+  minifyHtml(html: string) {
+    const minificationOptions = this.options.build.html.minify
 
     if (!minificationOptions) {
       return html

packages/nuxt3/src/server/jsdom.ts

@@ -1,4 +1,5 @@
 import consola from 'consola'
+import { BaseOptions, DOMWindow, VirtualConsole } from 'jsdom'
 import { DeterminedGlobals, timeout } from 'nuxt/utils'
 
 interface Options {
@@ -28,12 +29,12 @@ export default async function renderAndGetWindow (
       throw e
     })
 
-  const options = Object.assign({
+  const options: BaseOptions = Object.assign({
     // Load subresources (https://github.com/tmpvar/jsdom#loading-subresources)
-    resources: 'usable',
-    runScripts: 'dangerously',
-    virtualConsole: true,
-    beforeParse (window: Window) {
+    resources: 'usable' as const,
+    runScripts: 'dangerously' as const,
+    virtualConsole: undefined,
+    beforeParse (window: DOMWindow) {
       // Mock window.scrollTo
       window.scrollTo = () => {}
     }
@@ -44,8 +45,8 @@ export default async function renderAndGetWindow (
   }
 
   if (options.virtualConsole) {
-    if (options.virtualConsole === true) {
-      options.virtualConsole = new jsdom.VirtualConsole().sendTo(consola)
+    if (options.virtualConsole === undefined) {
+      options.virtualConsole = new jsdom.VirtualConsole().sendTo(consola as unknown as Console)
     }
     // Throw error when window creation failed
     options.virtualConsole.on('jsdomError', jsdomErrHandler)
@@ -58,13 +59,13 @@ export default async function renderAndGetWindow (
 
   if (!nuxtExists) {
     const error = new Error('Could not load the nuxt app')
-    error.body = window.document.body.innerHTML
+    ;(error as any).body = window.document.body.innerHTML
     window.close()
     throw error
   }
 
   // Used by Nuxt.js to say when the components are loaded and the app ready
-  await timeout(new Promise((resolve) => {
+  await timeout(new Promise<DOMWindow>((resolve) => {
     window[loadedCallback] = () => resolve(window)
   }), loadingTimeout, `Components loading in renderAndGetWindow was not completed in ${loadingTimeout / 1000}s`)
 

packages/nuxt3/src/server/listener.ts

@@ -8,6 +8,16 @@ import pify from 'pify'
 
 let RANDOM_PORT = '0'
 
+interface ListenerOptions {
+  port: number | string
+  host: string
+  socket: string
+  https: boolean
+  app: any
+  dev: boolean
+  baseURL: string
+}
+
 export default class Listener {
   port: number | string
   host: string
@@ -22,7 +32,7 @@ export default class Listener {
   server: null | http.Server
   address: null
   url: null | string
-  constructor ({ port, host, socket, https, app, dev, baseURL }) {
+  constructor ({ port, host, socket, https, app, dev, baseURL }: ListenerOptions) {
     // Options
     this.port = port
     this.host = host

packages/nuxt3/src/server/server.ts

@@ -33,7 +33,7 @@ export default class Server {
   nuxt: Nuxt
   globals: DeterminedGlobals
   options: Nuxt['options']
-  publicPath: boolean
+  publicPath: string
   renderer: VueRenderer
   resources: {
     clientManifest?: Manifest
@@ -114,7 +114,7 @@ export default class Server {
       }
     }
 
-    if (this.options.server.timing) {
+    if (typeof this.options.server !== 'boolean' && this.options.server.timing) {
       this.useMiddleware(createTimingMiddleware(this.options.server.timing))
     }
 

packages/nuxt3/src/utils/resolve.ts

@@ -67,8 +67,8 @@ interface AliasOptions {
   warn?: boolean
 }
 
-export function defineAlias (
-  src: string,
+export function defineAlias <O extends Record<string, any>>(
+  src: O,
   target: Record<string, any>,
   prop: string | string[],
   opts: AliasOptions = {}

packages/nuxt3/src/utils/route.ts

@@ -213,7 +213,7 @@ export const createRoutes = function createRoutes ({
 }
 
 // Guard dir1 from dir2 which can be indiscriminately removed
-export const guardDir = function guardDir (options: Record<string, unknown>, key1: string, key2: string) {
+export const guardDir = function guardDir (options: Record<string, any>, key1: string, key2: string) {
   const dir1 = get(options, key1, false) as string
   const dir2 = get(options, key2, false) as string
 

packages/nuxt3/src/utils/timer.ts

@@ -15,8 +15,8 @@ async function promiseFinally<T> (
   return result
 }
 
-export const timeout = function timeout (
-  fn: () => any,
+export const timeout = function timeout <T>(
+  fn: Promise<T>,
   ms: number,
   msg: string
 ) {