diff --git a/src/compiler/parser.ts b/src/compiler/parser.ts
index e391408b419..16196e277dc 100644
--- a/src/compiler/parser.ts
+++ b/src/compiler/parser.ts
@@ -546,7 +546,7 @@ namespace ts {
 
         function getLanguageVariant(fileName: string) {
             // .tsx and .jsx files are treated as jsx language variant.
-            return fileExtensionIs(fileName, ".tsx") || fileExtensionIs(fileName, ".jsx") ?  LanguageVariant.JSX  : LanguageVariant.Standard;
+            return fileExtensionIs(fileName, ".tsx") || fileExtensionIs(fileName, ".jsx") || fileExtensionIs(fileName, '.js') ?  LanguageVariant.JSX  : LanguageVariant.Standard;
         }
 
         function initializeState(fileName: string, _sourceText: string, languageVersion: ScriptTarget, isJavaScriptFile: boolean, _syntaxCursor: IncrementalParser.SyntaxCursor) {