vitejs · bluwy · Apr 22, 2026 · Apr 20, 2026 · Apr 20, 2026 · Apr 20, 2026
diff --git a/eslint.config.js b/eslint.config.js
@@ -155,32 +155,25 @@ export default defineConfig(
       '@typescript-eslint/consistent-type-definitions': 'off',
       '@typescript-eslint/prefer-for-of': 'off',
       '@typescript-eslint/prefer-function-type': 'off',
-      // disable typecheck-specific rules (but worth revisiting again)
-      '@typescript-eslint/await-thenable': 'off',
-      '@typescript-eslint/dot-notation': 'off',
-      '@typescript-eslint/no-base-to-string': 'off',
-      '@typescript-eslint/no-duplicate-type-constituents': 'off',
-      '@typescript-eslint/no-implied-eval': 'off',
+      // disable typecheck-specific rules
+      '@typescript-eslint/await-thenable': 'off', // does not handle `void | Promise<void>` well
+      '@typescript-eslint/no-base-to-string': 'off', // does not matter for us
+      '@typescript-eslint/no-implied-eval': 'off', // we intentionally use `Function()`
       '@typescript-eslint/no-floating-promises': 'off',
       '@typescript-eslint/no-misused-promises': 'off',
-      '@typescript-eslint/no-redundant-type-constituents': 'off',
+      '@typescript-eslint/no-redundant-type-constituents': 'off', // hard to handle some cases
       '@typescript-eslint/no-unnecessary-type-assertion': 'off',
       '@typescript-eslint/no-unsafe-argument': 'off',
       '@typescript-eslint/no-unsafe-assignment': 'off',
       '@typescript-eslint/no-unsafe-call': 'off',
-      '@typescript-eslint/no-unsafe-enum-comparison': 'off',
       '@typescript-eslint/no-unsafe-member-access': 'off',
       '@typescript-eslint/no-unsafe-return': 'off',
-      '@typescript-eslint/non-nullable-type-assertion-style': 'off',
       '@typescript-eslint/only-throw-error': 'off',
-      '@typescript-eslint/prefer-includes': 'off',
       '@typescript-eslint/prefer-nullish-coalescing': 'off',
       '@typescript-eslint/prefer-optional-chain': 'off',
-      '@typescript-eslint/prefer-promise-reject-errors': 'off',
-      '@typescript-eslint/prefer-string-starts-ends-with': 'off',
+      '@typescript-eslint/prefer-string-starts-ends-with': 'off', // prefer indexed access for better performance
       '@typescript-eslint/require-await': 'off',
-      '@typescript-eslint/restrict-plus-operands': 'off',
-      '@typescript-eslint/restrict-template-expressions': 'off',
+      '@typescript-eslint/restrict-template-expressions': 'off', // does not matter for us
       '@typescript-eslint/unbound-method': 'off',
 
       'import-x/no-duplicates': 'error',
@@ -376,6 +369,14 @@ export default defineConfig(
       '@typescript-eslint/ban-ts-comment': 'off',
     },
   },
+  {
+    name: 'disables/test-dts',
+    files: ['**/__tests_dts__/**/*.?([cm])[jt]s?(x)'],
+    rules: {
+      // disable typecheck-specific rules
+      '@typescript-eslint/no-duplicate-type-constituents': 'off',
+    },
+  },
   {
     name: 'disables/typechecking',
     files: [

diff --git a/packages/vite/rolldown.config.ts b/packages/vite/rolldown.config.ts
@@ -3,7 +3,7 @@ import path from 'node:path'
 import MagicString from 'magic-string'
 import type { Plugin } from 'rolldown'
 import { defineConfig } from 'rolldown'
-import { init, parse } from 'es-module-lexer'
+import { ImportType, init, parse } from 'es-module-lexer'
 import licensePlugin from './rollupLicensePlugin'
 
 // eslint-disable-next-line n/no-unsupported-features/node-builtins
@@ -321,7 +321,10 @@ function buildTimeImportMetaUrlPlugin(): Plugin {
         const s = new MagicString(code)
         const [imports] = parse(code)
         for (const { t, ss, se } of imports) {
-          if (t === 3 && code.slice(se, se + 4) === '.url') {
+          if (
+            t === ImportType.ImportMeta &&
+            code.slice(se, se + 4) === '.url'
+          ) {
             // ignore import.meta.url with /** #__KEEP__ */ comment
             if (keepCommentRE.test(code.slice(0, ss))) {
               keepCommentRE.lastIndex = 0

diff --git a/packages/vite/rollupLicensePlugin.ts b/packages/vite/rollupLicensePlugin.ts
@@ -16,6 +16,7 @@ export default function licensePlugin(
       // MIT Licensed https://github.com/rollup/rollup/blob/master/LICENSE-CORE.md
       const coreLicense = fs.readFileSync(
         new URL('../../LICENSE', import.meta.url),
+        'utf-8',
       )
 
       const deps = sortDependencies(dependencies)

diff --git a/packages/vite/src/client/client.ts b/packages/vite/src/client/client.ts
@@ -395,7 +395,7 @@ function waitForSuccessfulPing(socketUrl: string) {
       document.removeEventListener('visibilitychange', onVisibilityChange)
       sharedWorker.port.close()
 
-      const data: { type: 'success' } | { type: 'error'; error: unknown } =
+      const data: { type: 'success' } | { type: 'error'; error: Error } =
         event.data
       if (data.type === 'error') {
         reject(data.error)

diff --git a/packages/vite/src/module-runner/evaluatedModules.ts b/packages/vite/src/module-runner/evaluatedModules.ts
@@ -14,7 +14,7 @@ export class EvaluatedModuleNode {
   public evaluated = false
   public meta: ResolvedResult | undefined
   public promise: Promise<any> | undefined
-  public exports: any | undefined
+  public exports: any
   public file: string
   public map: DecodedMap | undefined
 

diff --git a/packages/vite/src/module-runner/sourcemap/interceptor.ts b/packages/vite/src/module-runner/sourcemap/interceptor.ts
@@ -271,7 +271,7 @@ function CallSiteToString(this: CallSite) {
   } else {
     fileName = this.getScriptNameOrSourceURL()
     if (!fileName && this.isEval()) {
-      fileLocation = this.getEvalOrigin() as string
+      fileLocation = this.getEvalOrigin()!
       fileLocation += ', ' // Expecting source position to follow.
     }
 
@@ -388,7 +388,7 @@ function wrapCallSite(frame: CallSite, state: State) {
       return position.column + 1
     }
     frame.getScriptNameOrSourceURL = function () {
-      return position.source as string
+      return position.source!
     }
     return frame
   }

diff --git a/packages/vite/src/module-runner/utils.ts b/packages/vite/src/module-runner/utils.ts
@@ -24,17 +24,14 @@ const questionRegex = /\?/g
 const hashRegex = /#/g
 
 function encodePathChars(filepath: string) {
-  if (filepath.indexOf('%') !== -1)
-    filepath = filepath.replace(percentRegEx, '%25')
+  if (filepath.includes('%')) filepath = filepath.replace(percentRegEx, '%25')
   // In posix, backslash is a valid character in paths:
-  if (!isWindows && filepath.indexOf('\\') !== -1)
+  if (!isWindows && filepath.includes('\\'))
     filepath = filepath.replace(backslashRegEx, '%5C')
-  if (filepath.indexOf('\n') !== -1)
-    filepath = filepath.replace(newlineRegEx, '%0A')
-  if (filepath.indexOf('\r') !== -1)
+  if (filepath.includes('\n')) filepath = filepath.replace(newlineRegEx, '%0A')
+  if (filepath.includes('\r'))
     filepath = filepath.replace(carriageReturnRegEx, '%0D')
-  if (filepath.indexOf('\t') !== -1)
-    filepath = filepath.replace(tabRegEx, '%09')
+  if (filepath.includes('\t')) filepath = filepath.replace(tabRegEx, '%09')
   return filepath
 }
 
@@ -59,10 +56,8 @@ export function posixPathToFileHref(posixPath: string): string {
   // Therefore, encoding is required to eliminate parsing them in different states.
   // This is done as an optimization to not creating a URL instance and
   // later triggering pathname setter, which impacts performance
-  if (resolved.indexOf('?') !== -1)
-    resolved = resolved.replace(questionRegex, '%3F')
-  if (resolved.indexOf('#') !== -1)
-    resolved = resolved.replace(hashRegex, '%23')
+  if (resolved.includes('?')) resolved = resolved.replace(questionRegex, '%3F')
+  if (resolved.includes('#')) resolved = resolved.replace(hashRegex, '%23')
   return new URL(`file://${resolved}`).href
 }
 

diff --git a/packages/vite/src/node/cli.ts b/packages/vite/src/node/cli.ts
@@ -70,7 +70,7 @@ export const stopProfiler = (
 ): void | Promise<void> => {
   if (!profileSession) return
   return new Promise((res, rej) => {
-    profileSession!.post('Profiler.stop', (err: any, { profile }: any) => {
+    profileSession!.post('Profiler.stop', (err, { profile }) => {
       // Write profile to disk, upload, etc.
       if (!err) {
         const outPath = path.resolve(

diff --git a/packages/vite/src/node/env.ts b/packages/vite/src/node/env.ts
@@ -85,7 +85,7 @@ export function loadEnv(
   // these are typically provided inline and should be prioritized
   for (const key in process.env) {
     if (prefixes.some((prefix) => key.startsWith(prefix))) {
-      env[key] = process.env[key] as string
+      env[key] = process.env[key]!
     }
   }
 

diff --git a/packages/vite/src/node/plugins/asset.ts b/packages/vite/src/node/plugins/asset.ts
@@ -64,13 +64,13 @@ export function registerCustomMime(): void {
   // https://github.com/lukeed/mrmime/issues/3
   // instead of `image/vnd.microsoft.icon` which is registered on IANA Media Types DB
   // image/x-icon should be used instead for better compatibility (https://github.com/h5bp/html5-boilerplate/issues/219)
-  mrmime.mimes['ico'] = 'image/x-icon'
+  mrmime.mimes.ico = 'image/x-icon'
   // https://mimesniff.spec.whatwg.org/#matching-an-image-type-pattern
-  mrmime.mimes['cur'] = 'image/x-icon'
+  mrmime.mimes.cur = 'image/x-icon'
   // https://developer.mozilla.org/en-US/docs/Web/Media/Formats/Containers#flac
-  mrmime.mimes['flac'] = 'audio/flac'
+  mrmime.mimes.flac = 'audio/flac'
   // https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/MIME_types/Common_types
-  mrmime.mimes['eot'] = 'application/vnd.ms-fontobject'
+  mrmime.mimes.eot = 'application/vnd.ms-fontobject'
 }
 
 export function renderAssetUrlInJS(

diff --git a/packages/vite/src/node/plugins/css.ts b/packages/vite/src/node/plugins/css.ts
@@ -2467,7 +2467,7 @@ async function loadSss(root: string): Promise<PostCSS.Syntax> {
   return cachedSss
 }
 
-declare const window: unknown | undefined
+declare const window: unknown
 declare const location: { href: string } | undefined
 
 // in unix, scss might append `location.href` in environments that shim `location`

diff --git a/packages/vite/src/node/plugins/html.ts b/packages/vite/src/node/plugins/html.ts
@@ -206,13 +206,13 @@ export async function traverseHtml(
   visitor: (node: DefaultTreeAdapterMap['node']) => void,
 ): Promise<void> {
   // lazy load compiler
-  const { parse } = await import('parse5')
+  const { parse, ErrorCodes } = await import('parse5')
   const warnings: ParseWarnings = {}
   const ast = parse(html, {
     scriptingEnabled: false, // parse inside <noscript>
     sourceCodeLocationInfo: true,
     onParseError: (e: ParserError) => {
-      handleParseError(e, html, filePath, warnings)
+      handleParseError(e, ErrorCodes, html, filePath, warnings)
     },
   })
   traverseNodes(ast, visitor)
@@ -239,7 +239,7 @@ export function getScriptInfo(node: DefaultTreeAdapterMap['element']): {
     if (p.name === 'src') {
       if (!src) {
         src = p
-        srcSourceCodeLocation = node.sourceCodeLocation?.attrs!['src']
+        srcSourceCodeLocation = node.sourceCodeLocation?.attrs!.src
       }
     } else if (p.name === 'type' && p.value === 'module') {
       isModule = true
@@ -316,25 +316,26 @@ function formatParseError(parserError: ParserError, id: string, html: string) {
 
 function handleParseError(
   parserError: ParserError,
+  errorCodes: typeof ErrorCodes,
   html: string,
   filePath: string,
   warnings: ParseWarnings,
 ) {
   switch (parserError.code) {
-    case 'missing-doctype':
+    case errorCodes.missingDoctype:
       // ignore missing DOCTYPE
       return
-    case 'abandoned-head-element-child':
+    case errorCodes.abandonedHeadElementChild:
       // Accept elements without closing tag in <head>
       return
-    case 'duplicate-attribute':
+    case errorCodes.duplicateAttribute:
       // Accept duplicate attributes #5966
       // The first attribute is used, browsers silently ignore duplicates
       return
-    case 'non-void-html-element-start-tag-with-trailing-solidus':
+    case errorCodes.nonVoidHtmlElementStartTagWithTrailingSolidus:
       // Allow self closing on non-void elements #10439
       return
-    case 'unexpected-question-mark-instead-of-tag-name':
+    case errorCodes.unexpectedQuestionMarkInsteadOfTagName:
       // Allow <?xml> declaration and <?> empty elements
       // lit generates <?>: https://github.com/lit/lit/issues/2470
       return
@@ -1085,7 +1086,7 @@ export function findNeedTransformStyleAttribute(
       (prop.value.includes('url(') || prop.value.includes('image-set(')),
   )
   if (!attr) return undefined
-  const location = node.sourceCodeLocation?.attrs?.['style']
+  const location = node.sourceCodeLocation?.attrs?.style
   return { attr, location }
 }
 

diff --git a/packages/vite/src/node/plugins/importAnalysisBuild.ts b/packages/vite/src/node/plugins/importAnalysisBuild.ts
@@ -211,7 +211,7 @@ export function buildImportAnalysisPlugin(config: ResolvedConfig): Plugin[] {
 
     renderChunk(code, _, { format }) {
       // make sure we only perform the preload logic in modern builds.
-      if (code.indexOf(isModernFlag) > -1) {
+      if (code.includes(isModernFlag)) {
         const re = new RegExp(isModernFlag, 'g')
         const isModern = String(format === 'es')
         const isModernWithPadding =
@@ -299,7 +299,7 @@ export function buildImportAnalysisPlugin(config: ResolvedConfig): Plugin[] {
         const chunk = bundle[file]
         // can't use chunk.dynamicImports.length here since some modules e.g.
         // dynamic import to constant json may get inlined.
-        if (chunk.type === 'chunk' && chunk.code.indexOf(preloadMarker) > -1) {
+        if (chunk.type === 'chunk' && chunk.code.includes(preloadMarker)) {
           const code = chunk.code
           let imports!: ImportSpecifier[]
           try {

diff --git a/packages/vite/src/node/server/hmr.ts b/packages/vite/src/node/server/hmr.ts
@@ -348,7 +348,7 @@ export function getSortedPluginsByHotUpdateHook(
     normal = 0,
     post = 0
   for (const plugin of plugins) {
-    const hook = plugin['hotUpdate'] ?? plugin['handleHotUpdate']
+    const hook = plugin.hotUpdate ?? plugin.handleHotUpdate
     if (hook) {
       if (typeof hook === 'object') {
         if (hook.order === 'pre') {

diff --git a/packages/vite/src/node/server/index.ts b/packages/vite/src/node/server/index.ts
@@ -978,7 +978,7 @@ export async function _createServer(
   // ping request handler
   // Keep the named function. The name is visible in debug logs via `DEBUG=connect:dispatcher ...`
   middlewares.use(function viteHMRPingMiddleware(req, res, next) {
-    if (req.headers['accept'] === 'text/x-vite-ping') {
+    if (req.headers.accept === 'text/x-vite-ping') {
       res.writeHead(204).end()
     } else {
       next()

diff --git a/packages/vite/src/node/server/middlewares/static.ts b/packages/vite/src/node/server/middlewares/static.ts
@@ -93,7 +93,7 @@ export function servePublicMiddleware(
 
   const toFilePath = (url: string) => {
     let filePath = cleanUrl(url)
-    if (filePath.indexOf('%') !== -1) {
+    if (filePath.includes('%')) {
       try {
         filePath = decodeURI(filePath)
       } catch {

diff --git a/packages/vite/src/node/server/pluginContainer.ts b/packages/vite/src/node/server/pluginContainer.ts
@@ -918,7 +918,7 @@ class PluginContext
 
   private _formatLog<E extends RollupLog>(
     e: string | E,
-    position?: number | { column: number; line: number } | undefined,
+    position?: number | { column: number; line: number },
   ): E {
     const err = (typeof e === 'string' ? new Error(e) : e) as E
     if (err.pluginCode) {

diff --git a/packages/vite/src/node/utils.ts b/packages/vite/src/node/utils.ts
@@ -62,7 +62,7 @@ export const createFilter = _createFilter as (
   include?: FilterPattern,
   exclude?: FilterPattern,
   options?: { resolve?: string | false | null },
-) => (id: string | unknown) => boolean
+) => (id: unknown) => boolean
 
 export { withFilter } from 'rolldown/filter'