diff --git a/server/src/config.ts b/server/src/config.ts
index 521edaf163..e50cae4166 100644
--- a/server/src/config.ts
+++ b/server/src/config.ts
@@ -77,6 +77,7 @@ export interface VLSConfig {
     experimental: {
       templateInterpolationService: boolean;
     };
+    extensions: string[];
   };
 }
 
@@ -140,7 +141,8 @@ export function getDefaultVLSConfig(): VLSFullConfig {
       },
       experimental: {
         templateInterpolationService: false
-      }
+      },
+      extensions: []
     },
     css: {},
     html: {
diff --git a/server/src/modes/script/javascript.ts b/server/src/modes/script/javascript.ts
index f5032f69ea..b8e1b36272 100644
--- a/server/src/modes/script/javascript.ts
+++ b/server/src/modes/script/javascript.ts
@@ -46,12 +46,7 @@ import { getComponentInfo } from './componentInfo';
 import { DependencyService, RuntimeLibrary } from '../../services/dependencyService';
 import { CodeActionData, CodeActionDataKind, OrganizeImportsActionData, RefactorActionData } from '../../types';
 import { IServiceHost } from '../../services/typescriptService/serviceHost';
-import {
-  isVirtualVueTemplateFile,
-  isVueFile,
-  toCompletionItemKind,
-  toSymbolKind
-} from '../../services/typescriptService/util';
+import { isVirtualVueTemplateFile, toCompletionItemKind, toSymbolKind } from '../../services/typescriptService/util';
 import * as Previewer from './previewer';
 import { isVCancellationRequested, VCancellationToken } from '../../utils/cancellationToken';
 import { EnvironmentService } from '../../services/EnvironmentService';
@@ -755,7 +750,7 @@ export async function getJavascriptMode(
         return [];
       }
 
-      const oldFileIsVue = isVueFile(oldPath);
+      const oldFileIsVue = env.isVueFile(oldPath);
       const formatSettings: ts.FormatCodeSettings = getFormatCodeSettings(env.getConfig());
       const preferences = getUserPreferencesByLanguageId(
         (sourceFile as any).scriptKind === tsModule.ScriptKind.JS ? 'javascript' : 'typescript'
@@ -773,7 +768,7 @@ export async function getJavascriptMode(
           continue;
         }
         const doc = getSourceDoc(fileName, program);
-        const bothNotVueFile = !oldFileIsVue && !isVueFile(fileName);
+        const bothNotVueFile = !oldFileIsVue && !env.isVueFile(fileName);
         if (bothNotVueFile) {
           continue;
         }
diff --git a/server/src/services/EnvironmentService.ts b/server/src/services/EnvironmentService.ts
index 29a89a0352..eb3cacfa03 100644
--- a/server/src/services/EnvironmentService.ts
+++ b/server/src/services/EnvironmentService.ts
@@ -11,6 +11,7 @@ export interface EnvironmentService {
   getVueVersion(): VueVersion;
   getSnippetFolder(): string;
   getGlobalComponentInfos(): BasicComponentInfo[];
+  isVueFile(path: string): boolean;
 }
 
 export function createEnvironmentService(
@@ -35,6 +36,7 @@ export function createEnvironmentService(
     getPackagePath: () => packagePath,
     getVueVersion: () => inferVueVersion(packagePath),
     getSnippetFolder: () => snippetFolder,
-    getGlobalComponentInfos: () => globalComponentInfos
+    getGlobalComponentInfos: () => globalComponentInfos,
+    isVueFile: (path: string) => ['.vue', ...$config.vetur.extensions].some(ext => path.endsWith(ext))
   };
 }
diff --git a/server/src/services/typescriptService/preprocess.ts b/server/src/services/typescriptService/preprocess.ts
index b7a10c7ba7..690f0b91c2 100644
--- a/server/src/services/typescriptService/preprocess.ts
+++ b/server/src/services/typescriptService/preprocess.ts
@@ -14,10 +14,11 @@ import {
 } from './transformTemplate';
 import { templateSourceMap } from './serviceHost';
 import { generateSourceMap } from './sourceMap';
-import { isVirtualVueTemplateFile, isVueFile } from './util';
+import { isVirtualVueTemplateFile } from './util';
 import { ChildComponent } from '../vueInfoService';
 import { kebabCase, snakeCase } from 'lodash';
 import { RuntimeLibrary } from '../dependencyService';
+import { EnvironmentService } from '../EnvironmentService';
 
 const importedComponentName = '__vlsComponent';
 
@@ -52,7 +53,8 @@ export function parseVueTemplate(text: string): string {
 
 export function createUpdater(
   tsModule: RuntimeLibrary['typescript'],
-  allChildComponentsInfo: Map<string, ChildComponent[]>
+  allChildComponentsInfo: Map<string, ChildComponent[]>,
+  env: EnvironmentService
 ) {
   const clssf = tsModule.createLanguageServiceSourceFile;
   const ulssf = tsModule.updateLanguageServiceSourceFile;
@@ -71,7 +73,7 @@ export function createUpdater(
       return;
     }
 
-    if (isVueFile(fileName)) {
+    if (env.isVueFile(fileName)) {
       modifyVueScript(tsModule, sourceFile);
       modificationTracker.add(sourceFile);
       return;
diff --git a/server/src/services/typescriptService/serviceHost.ts b/server/src/services/typescriptService/serviceHost.ts
index 09be5b0793..9611abcb05 100644
--- a/server/src/services/typescriptService/serviceHost.ts
+++ b/server/src/services/typescriptService/serviceHost.ts
@@ -9,7 +9,7 @@ import { getFileFsPath, getFilePath, normalizeFileNameToFsPath } from '../../uti
 import * as bridge from './bridge';
 import { getVueSys } from './vueSys';
 import { TemplateSourceMap, stringifySourceMapNodes } from './sourceMap';
-import { isVirtualVueTemplateFile, isVueFile } from './util';
+import { isVirtualVueTemplateFile } from './util';
 import { logger } from '../../log';
 import { ModuleResolutionCache } from './moduleResolutionCache';
 import { globalScope } from './transformTemplate';
@@ -25,12 +25,13 @@ const NEWLINE = process.platform === 'win32' ? '\r\n' : '\n';
  */
 const allChildComponentsInfo = new Map<string, ChildComponent[]>();
 
-function patchTS(tsModule: RuntimeLibrary['typescript']) {
+function patchTS(tsModule: RuntimeLibrary['typescript'], env: EnvironmentService) {
   // Patch typescript functions to insert `import Vue from 'vue'` and `new Vue` around export default.
   // NOTE: this is a global hack that all ts instances after is changed
   const { createLanguageServiceSourceFile, updateLanguageServiceSourceFile } = createUpdater(
     tsModule,
-    allChildComponentsInfo
+    allChildComponentsInfo,
+    env
   );
   (tsModule as any).createLanguageServiceSourceFile = createLanguageServiceSourceFile;
   (tsModule as any).updateLanguageServiceSourceFile = updateLanguageServiceSourceFile;
@@ -89,7 +90,7 @@ export function getServiceHost(
   env: EnvironmentService,
   updatedScriptRegionDocuments: LanguageModelCache<TextDocument>
 ): IServiceHost {
-  patchTS(tsModule);
+  patchTS(tsModule, env);
 
   let currentScriptDoc: TextDocument;
 
@@ -298,7 +299,7 @@ export function getServiceHost(
           return (tsModule as any).getScriptKindFromFileName(fileName);
         }
 
-        if (isVueFile(fileName)) {
+        if (env.isVueFile(fileName)) {
           const uri = URI.file(fileName);
           const fileFsPath = normalizeFileNameToFsPath(fileName);
           let doc = localScriptRegionDocuments.get(fileFsPath);
@@ -354,7 +355,7 @@ export function getServiceHost(
             return cachedResolvedModule;
           }
 
-          if (!isVueFile(name)) {
+          if (!env.isVueFile(name)) {
             const tsResolvedModule = tsModule.resolveModuleName(name, containingFile, options, tsModule.sys)
               .resolvedModule;
 
@@ -446,7 +447,7 @@ export function getServiceHost(
         }
 
         // js/ts files in workspace
-        if (!isVueFile(fileFsPath)) {
+        if (!env.isVueFile(fileFsPath)) {
           if (projectFileSnapshots.has(fileFsPath)) {
             return projectFileSnapshots.get(fileFsPath);
           }
diff --git a/server/src/services/typescriptService/util.ts b/server/src/services/typescriptService/util.ts
index abbe7e80e3..f187ab0cc9 100644
--- a/server/src/services/typescriptService/util.ts
+++ b/server/src/services/typescriptService/util.ts
@@ -1,10 +1,6 @@
 import type ts from 'typescript';
 import { CompletionItemKind, SymbolKind } from 'vscode-languageserver';
 
-export function isVueFile(path: string) {
-  return path.endsWith('.vue');
-}
-
 /**
  * If the path ends with `.vue.ts`, it's a `.vue` file pre-processed by Vetur
  * to be used in TS Language Service
diff --git a/vti/src/initParams.ts b/vti/src/initParams.ts
index 4157652992..5e2f4db97b 100644
--- a/vti/src/initParams.ts
+++ b/vti/src/initParams.ts
@@ -75,7 +75,8 @@ function getDefaultVLSConfig() {
       },
       experimental: {
         templateInterpolationService: false
-      }
+      },
+      extentions: []
     },
     css: {},
     html: {