diff --git a/packages/vite/src/node/__tests__/utils.spec.ts b/packages/vite/src/node/__tests__/utils.spec.ts
index 3bf82f6b86f84b..302f5549e2da53 100644
--- a/packages/vite/src/node/__tests__/utils.spec.ts
+++ b/packages/vite/src/node/__tests__/utils.spec.ts
@@ -1,40 +1,67 @@
-import { injectQuery, isWindows } from '../utils'
+import { injectQuery, isJSRequest, isWindows } from '../utils'
 
-if (isWindows) {
-  // this test will work incorrectly on unix systems
-  test('normalize windows path', () => {
-    expect(injectQuery('C:\\User\\Vite\\Project', 'direct')).toEqual(
-      'C:/User/Vite/Project?direct'
+describe('injectQuery', () => {
+  if (isWindows) {
+    // this test will work incorrectly on unix systems
+    test('normalize windows path', () => {
+      expect(injectQuery('C:\\User\\Vite\\Project', 'direct')).toEqual(
+        'C:/User/Vite/Project?direct'
+      )
+    })
+  }
+
+  test('path with multiple spaces', () => {
+    expect(injectQuery('/usr/vite/path with space', 'direct')).toEqual(
+      '/usr/vite/path with space?direct'
     )
   })
-}
 
-test('path with multiple spaces', () => {
-  expect(injectQuery('/usr/vite/path with space', 'direct')).toEqual(
-    '/usr/vite/path with space?direct'
-  )
-})
+  test('path with multiple % characters', () => {
+    expect(injectQuery('/usr/vite/not%20a%20space', 'direct')).toEqual(
+      '/usr/vite/not%20a%20space?direct'
+    )
+  })
 
-test('path with multiple % characters', () => {
-  expect(injectQuery('/usr/vite/not%20a%20space', 'direct')).toEqual(
-    '/usr/vite/not%20a%20space?direct'
-  )
-})
+  test('path with %25', () => {
+    expect(injectQuery('/usr/vite/%25hello%25', 'direct')).toEqual(
+      '/usr/vite/%25hello%25?direct'
+    )
+  })
 
-test('path with %25', () => {
-  expect(injectQuery('/usr/vite/%25hello%25', 'direct')).toEqual(
-    '/usr/vite/%25hello%25?direct'
-  )
-})
+  test('path with unicode', () => {
+    expect(injectQuery('/usr/vite/東京', 'direct')).toEqual(
+      '/usr/vite/東京?direct'
+    )
+  })
 
-test('path with unicode', () => {
-  expect(injectQuery('/usr/vite/東京', 'direct')).toEqual(
-    '/usr/vite/東京?direct'
-  )
+  test('path with unicode, space, and %', () => {
+    expect(injectQuery('/usr/vite/東京 %20 hello', 'direct')).toEqual(
+      '/usr/vite/東京 %20 hello?direct'
+    )
+  })
 })
 
-test('path with unicode, space, and %', () => {
-  expect(injectQuery('/usr/vite/東京 %20 hello', 'direct')).toEqual(
-    '/usr/vite/東京 %20 hello?direct'
-  )
+describe('isJSRequest', () => {
+  const knownJsSrcExtensions = ['.js', '.ts']
+  test.each([
+    ['', true], // bare imports are js
+    ['.js', true],
+    ['.ts', true],
+    ['.x', false], // not in extensions list => false
+    ['/', false] // directory => false
+  ])('path ending with "%s" returns %s', (suffix, expected) => {
+    const path = `/x/y/foo${suffix}`
+    expect(isJSRequest(path, knownJsSrcExtensions)).toBe(expected)
+    // also tests combinations of querystring and hash, must be the same result
+    expect(isJSRequest(`${path}?foo=.js`, knownJsSrcExtensions)).toBe(expected)
+    expect(isJSRequest(`${path}#.js`, knownJsSrcExtensions)).toBe(expected)
+    expect(isJSRequest(`${path}?foo=.js#.js`, knownJsSrcExtensions)).toBe(
+      expected
+    )
+    expect(isJSRequest(`${path}?foo=.x`, knownJsSrcExtensions)).toBe(expected)
+    expect(isJSRequest(`${path}#.x`, knownJsSrcExtensions)).toBe(expected)
+    expect(isJSRequest(`${path}?foo=.x#.x`, knownJsSrcExtensions)).toBe(
+      expected
+    )
+  })
 })
diff --git a/packages/vite/src/node/config.ts b/packages/vite/src/node/config.ts
index 5ef64be1f33454..0145399e2bc5a2 100644
--- a/packages/vite/src/node/config.ts
+++ b/packages/vite/src/node/config.ts
@@ -21,7 +21,11 @@ import { ESBuildOptions } from './plugins/esbuild'
 import dotenv from 'dotenv'
 import dotenvExpand from 'dotenv-expand'
 import { Alias, AliasOptions } from 'types/alias'
-import { CLIENT_DIR, DEFAULT_ASSETS_RE } from './constants'
+import {
+  CLIENT_DIR,
+  DEFAULT_ASSETS_RE,
+  DEFAULT_KNOWN_JS_SRC_EXTENSIONS
+} from './constants'
 import {
   InternalResolveOptions,
   ResolveOptions,
@@ -129,6 +133,13 @@ export interface UserConfig {
    * Specify additional files to be treated as static assets.
    */
   assetsInclude?: string | RegExp | (string | RegExp)[]
+  /**
+   * Specify additional extensions to be treated as sources of js modules
+   * requires plugins to be installed that transform the extensions!
+   *
+   * Plugin authors should set this with the config hook
+   */
+  knownJsSrcExtensions?: string[]
   /**
    * Server specific options, e.g. host, port, https...
    */
@@ -195,7 +206,12 @@ export interface InlineConfig extends UserConfig {
 export type ResolvedConfig = Readonly<
   Omit<
     UserConfig,
-    'plugins' | 'alias' | 'dedupe' | 'assetsInclude' | 'optimizeDeps'
+    | 'plugins'
+    | 'alias'
+    | 'dedupe'
+    | 'assetsInclude'
+    | 'optimizeDeps'
+    | 'knownJsSrcExtensions'
   > & {
     configFile: string | undefined
     configFileDependencies: string[]
@@ -214,6 +230,7 @@ export type ResolvedConfig = Readonly<
     server: ResolvedServerOptions
     build: ResolvedBuildOptions
     assetsInclude: (file: string) => boolean
+    knownJsSrcExtensions: string[]
     logger: Logger
     createResolver: (options?: Partial<InternalResolveOptions>) => ResolveFn
     optimizeDeps: Omit<DepOptimizationOptions, 'keepNames'>
@@ -270,6 +287,11 @@ export async function resolveConfig(
   // user config may provide an alternative mode
   mode = config.mode || mode
 
+  // user config may provide alternative default known js src extensions
+  if (!config.knownJsSrcExtensions) {
+    config.knownJsSrcExtensions = [...DEFAULT_KNOWN_JS_SRC_EXTENSIONS]
+  }
+
   // resolve plugins
   const rawUserPlugins = (config.plugins || []).flat().filter((p) => {
     return p && (!p.apply || p.apply === command)
@@ -390,6 +412,15 @@ export async function resolveConfig(
         )
       : ''
 
+  //ensure leading dot and deduplicate
+  const resolvedKnownJsSrcExtensions = [
+    ...new Set(
+      config.knownJsSrcExtensions?.map((ext) =>
+        ext.startsWith('.') ? ext : `.${ext}`
+      )
+    )
+  ]
+
   const resolved: ResolvedConfig = {
     ...config,
     configFile: configFile ? normalizePath(configFile) : undefined,
@@ -416,6 +447,7 @@ export async function resolveConfig(
     assetsInclude(file: string) {
       return DEFAULT_ASSETS_RE.test(file) || assetsFilter(file)
     },
+    knownJsSrcExtensions: resolvedKnownJsSrcExtensions,
     logger,
     createResolver,
     optimizeDeps: {
diff --git a/packages/vite/src/node/constants.ts b/packages/vite/src/node/constants.ts
index 4352869419d897..b76bba9951d412 100644
--- a/packages/vite/src/node/constants.ts
+++ b/packages/vite/src/node/constants.ts
@@ -15,6 +15,19 @@ export const DEFAULT_EXTENSIONS = [
   '.json'
 ]
 
+// warning, these are only default values. At runtime you must check config.knownJsSrcExtensions
+export const DEFAULT_KNOWN_JS_SRC_EXTENSIONS = [
+  '.js',
+  '.ts',
+  '.jsx',
+  '.tsx',
+  '.mjs',
+  // the extensions below should be removed once their respective plugins add them via config hook
+  '.vue',
+  '.marko',
+  '.svelte'
+]
+
 export const JS_TYPES_RE = /\.(?:j|t)sx?$|\.mjs$/
 
 export const OPTIMIZABLE_ENTRY_RE = /\.(?:m?js|ts)$/
diff --git a/packages/vite/src/node/plugins/importAnalysis.ts b/packages/vite/src/node/plugins/importAnalysis.ts
index 4c5c66ce7c52b3..ff09e7184a54fc 100644
--- a/packages/vite/src/node/plugins/importAnalysis.ts
+++ b/packages/vite/src/node/plugins/importAnalysis.ts
@@ -48,12 +48,12 @@ const clientDir = normalizePath(CLIENT_DIR)
 const skipRE = /\.(map|json)$/
 const canSkip = (id: string) => skipRE.test(id) || isDirectCSSRequest(id)
 
-function isExplicitImportRequired(url: string) {
-  return !isJSRequest(cleanUrl(url)) && !isCSSRequest(url)
+function isExplicitImportRequired(url: string, knownJSSrcExtensions: string[]) {
+  return !isJSRequest(url, knownJSSrcExtensions) && !isCSSRequest(url)
 }
 
-function markExplicitImport(url: string) {
-  if (isExplicitImportRequired(url)) {
+function markExplicitImport(url: string, knownJSSrcExtensions: string[]) {
+  if (isExplicitImportRequired(url, knownJSSrcExtensions)) {
     return injectQuery(url, 'import')
   }
   return url
@@ -89,7 +89,7 @@ function markExplicitImport(url: string) {
  *     ```
  */
 export function importAnalysisPlugin(config: ResolvedConfig): Plugin {
-  const { root, base } = config
+  const { root, base, knownJsSrcExtensions } = config
   const clientPublicPath = path.posix.join(base, CLIENT_PUBLIC_PATH)
 
   let server: ViteDevServer
@@ -120,7 +120,7 @@ export function importAnalysisPlugin(config: ResolvedConfig): Plugin {
         imports = parseImports(source)[0]
       } catch (e) {
         const isVue = importer.endsWith('.vue')
-        const maybeJSX = !isVue && isJSRequest(importer)
+        const maybeJSX = !isVue && isJSRequest(importer, knownJsSrcExtensions)
 
         const msg = isVue
           ? `Install @vitejs/plugin-vue to handle .vue files.`
@@ -217,7 +217,7 @@ export function importAnalysisPlugin(config: ResolvedConfig): Plugin {
         // make the URL browser-valid if not SSR
         if (!ssr) {
           // mark non-js/css imports with `?import`
-          url = markExplicitImport(url)
+          url = markExplicitImport(url, knownJsSrcExtensions)
 
           // for relative js/css imports, inherit importer's version query
           // do not do this for unknown type imports, otherwise the appended
@@ -416,7 +416,7 @@ export function importAnalysisPlugin(config: ResolvedConfig): Plugin {
           }
           if (
             !/^('.*'|".*"|`.*`)$/.test(url) ||
-            isExplicitImportRequired(url.slice(1, -1))
+            isExplicitImportRequired(url.slice(1, -1), knownJsSrcExtensions)
           ) {
             needQueryInjectHelper = true
             str().overwrite(start, end, `__vite__injectQuery(${url}, 'import')`)
@@ -471,7 +471,7 @@ export function importAnalysisPlugin(config: ResolvedConfig): Plugin {
       const normalizedAcceptedUrls = new Set<string>()
       for (const { url, start, end } of acceptedUrls) {
         const [normalized] = await moduleGraph.resolveUrl(
-          toAbsoluteUrl(markExplicitImport(url))
+          toAbsoluteUrl(markExplicitImport(url, knownJsSrcExtensions))
         )
         normalizedAcceptedUrls.add(normalized)
         str().overwrite(start, end, JSON.stringify(normalized))
diff --git a/packages/vite/src/node/server/middlewares/transform.ts b/packages/vite/src/node/server/middlewares/transform.ts
index 963d11cd76ec45..3e22493ae2e26a 100644
--- a/packages/vite/src/node/server/middlewares/transform.ts
+++ b/packages/vite/src/node/server/middlewares/transform.ts
@@ -39,7 +39,7 @@ export function transformMiddleware(
   server: ViteDevServer
 ): Connect.NextHandleFunction {
   const {
-    config: { root, logger, cacheDir },
+    config: { root, logger, cacheDir, knownJsSrcExtensions },
     moduleGraph
   } = server
 
@@ -132,7 +132,7 @@ export function transformMiddleware(
       }
 
       if (
-        isJSRequest(url) ||
+        isJSRequest(url, knownJsSrcExtensions) ||
         isImportRequest(url) ||
         isCSSRequest(url) ||
         isHTMLProxy(url)
diff --git a/packages/vite/src/node/utils.ts b/packages/vite/src/node/utils.ts
index ceaff9799a38ad..f2dfcff64c9279 100644
--- a/packages/vite/src/node/utils.ts
+++ b/packages/vite/src/node/utils.ts
@@ -106,16 +106,13 @@ export const isExternalUrl = (url: string): boolean => externalRE.test(url)
 export const dataUrlRE = /^\s*data:/i
 export const isDataUrl = (url: string): boolean => dataUrlRE.test(url)
 
-const knownJsSrcRE = /\.((j|t)sx?|mjs|vue|marko|svelte)($|\?)/
-export const isJSRequest = (url: string): boolean => {
+export const isJSRequest = (
+  url: string,
+  knownJSSrcExtensions: string[]
+): boolean => {
   url = cleanUrl(url)
-  if (knownJsSrcRE.test(url)) {
-    return true
-  }
-  if (!path.extname(url) && !url.endsWith('/')) {
-    return true
-  }
-  return false
+  const ext = path.extname(url)
+  return ext ? knownJSSrcExtensions.includes(ext) : !url.endsWith('/')
 }
 
 const importQueryRE = /(\?|&)import=?(?:&|$)/