diff --git a/extensions/typescript/src/features/bufferSyncSupport.ts b/extensions/typescript/src/features/bufferSyncSupport.ts
index 975d4e9f529..1d9b940f563 100644
--- a/extensions/typescript/src/features/bufferSyncSupport.ts
+++ b/extensions/typescript/src/features/bufferSyncSupport.ts
@@ -9,6 +9,7 @@ import { workspace, TextDocument, TextDocumentChangeEvent, TextDocumentContentCh
 import * as Proto from '../protocol';
 import { ITypescriptServiceClient } from '../typescriptService';
 import { Delayer } from '../utils/async';
+import * as languageModeIds from '../utils/languageModeIds';
 
 interface IDiagnosticRequestor {
 	requestDiagnostic(filepath: string): void;
@@ -16,10 +17,10 @@ interface IDiagnosticRequestor {
 
 function mode2ScriptKind(mode: string): 'TS' | 'TSX' | 'JS' | 'JSX' | undefined {
 	switch (mode) {
-		case 'typescript': return 'TS';
-		case 'typescriptreact': return 'TSX';
-		case 'javascript': return 'JS';
-		case 'javascriptreact': return 'JSX';
+		case languageModeIds.typescript: return 'TS';
+		case languageModeIds.typescriptreact: return 'TSX';
+		case languageModeIds.javascript: return 'JS';
+		case languageModeIds.javascriptreact: return 'JSX';
 	}
 	return undefined;
 }
diff --git a/extensions/typescript/src/features/completionItemProvider.ts b/extensions/typescript/src/features/completionItemProvider.ts
index 2036add07d1..b7cbf17f729 100644
--- a/extensions/typescript/src/features/completionItemProvider.ts
+++ b/extensions/typescript/src/features/completionItemProvider.ts
@@ -15,6 +15,8 @@ import { tsTextSpanToVsRange, vsPositionToTsFileLocation } from '../utils/conver
 
 import * as nls from 'vscode-nls';
 import { applyCodeAction } from '../utils/codeAction';
+import * as languageModeIds from '../utils/languageModeIds';
+
 let localize = nls.loadMessageBundle();
 
 class MyCompletionItem extends CompletionItem {
@@ -236,7 +238,7 @@ export default class TypeScriptCompletionItemProvider implements CompletionItemP
 			const body = msg.body;
 			if (body) {
 				// Only enable dot completions in TS files for now
-				let enableDotCompletions = document && (document.languageId === 'typescript' || document.languageId === 'typescriptreact');
+				let enableDotCompletions = document && (document.languageId === languageModeIds.typescript || document.languageId === languageModeIds.typescriptreact);
 
 				// TODO: Workaround for https://github.com/Microsoft/TypeScript/issues/13456
 				// Only enable dot completions when previous character is an identifier.
diff --git a/extensions/typescript/src/typescriptMain.ts b/extensions/typescript/src/typescriptMain.ts
index 839f4ad5fd0..151d239504a 100644
--- a/extensions/typescript/src/typescriptMain.ts
+++ b/extensions/typescript/src/typescriptMain.ts
@@ -35,6 +35,7 @@ import { getContributedTypeScriptServerPlugins, TypeScriptServerPlugin } from '.
 import { openOrCreateConfigFile, isImplicitProjectConfigFile } from './utils/tsconfig';
 import { tsLocationToVsPosition } from './utils/convert';
 import FormattingConfigurationManager from './features/formattingConfigurationManager';
+import * as languageModeIds from './utils/languageModeIds';
 
 interface LanguageDescription {
 	id: string;
@@ -54,21 +55,16 @@ interface ProjectConfigMessageItem extends MessageItem {
 	id: ProjectConfigAction;
 }
 
-const MODE_ID_TS = 'typescript';
-const MODE_ID_TSX = 'typescriptreact';
-const MODE_ID_JS = 'javascript';
-const MODE_ID_JSX = 'javascriptreact';
-
 const standardLanguageDescriptions: LanguageDescription[] = [
 	{
 		id: 'typescript',
 		diagnosticSource: 'ts',
-		modeIds: [MODE_ID_TS, MODE_ID_TSX],
+		modeIds: [languageModeIds.typescript, languageModeIds.typescriptreact],
 		configFile: 'tsconfig.json'
 	}, {
 		id: 'javascript',
 		diagnosticSource: 'js',
-		modeIds: [MODE_ID_JS, MODE_ID_JSX],
+		modeIds: [languageModeIds.javascript, languageModeIds.javascriptreact],
 		configFile: 'jsconfig.json'
 	}
 ];
diff --git a/extensions/typescript/src/utils/languageModeIds.ts b/extensions/typescript/src/utils/languageModeIds.ts
new file mode 100644
index 00000000000..f69fd1295df
--- /dev/null
+++ b/extensions/typescript/src/utils/languageModeIds.ts
@@ -0,0 +1,9 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+export const typescript = 'typescript';
+export const typescriptreact = 'typescriptreact';
+export const javascript = 'javascript';
+export const javascriptreact = 'javascriptreact';
\ No newline at end of file
diff --git a/extensions/typescript/src/utils/projectStatus.ts b/extensions/typescript/src/utils/projectStatus.ts
index f46f509e674..704494c7466 100644
--- a/extensions/typescript/src/utils/projectStatus.ts
+++ b/extensions/typescript/src/utils/projectStatus.ts
@@ -8,9 +8,10 @@ import { ITypescriptServiceClient } from '../typescriptService';
 import { loadMessageBundle } from 'vscode-nls';
 import { dirname } from 'path';
 import { openOrCreateConfigFile, isImplicitProjectConfigFile } from './tsconfig';
+import * as languageModeIds from '../utils/languageModeIds';
 
 const localize = loadMessageBundle();
-const selector = ['javascript', 'javascriptreact'];
+const selector = [languageModeIds.javascript, languageModeIds.javascriptreact];
 
 
 interface Hint {
diff --git a/extensions/typescript/src/utils/versionStatus.ts b/extensions/typescript/src/utils/versionStatus.ts
index 901ca1e9737..78b5d0167c0 100644
--- a/extensions/typescript/src/utils/versionStatus.ts
+++ b/extensions/typescript/src/utils/versionStatus.ts
@@ -5,6 +5,7 @@
 
 import * as vscode from 'vscode';
 import { TypeScriptVersion } from './versionProvider';
+import * as languageModeIds from './languageModeIds';
 
 export default class VersionStatus {
 	private onChangeEditorSub: vscode.Disposable;
@@ -37,7 +38,7 @@ export default class VersionStatus {
 		}
 
 		const doc = vscode.window.activeTextEditor.document;
-		if (vscode.languages.match('typescript', doc) || vscode.languages.match('typescriptreact', doc)) {
+		if (vscode.languages.match([languageModeIds.typescript, languageModeIds.typescriptreact], doc)) {
 			this.versionBarEntry.show();
 			return;
 		}