Merge pull request #14493 from Microsoft/master-fixEmitExtraESModuleMark

[Master] Do not emit ESModule marker if file is not external module

Author: yuit

src/compiler/transformers/module/module.ts

@@ -55,9 +55,7 @@ namespace ts {
          * @param node The SourceFile node.
          */
         function transformSourceFile(node: SourceFile) {
-            if (isDeclarationFile(node)
-                || !(isExternalModule(node)
-                    || compilerOptions.isolatedModules)) {
+            if (isDeclarationFile(node) || !(isExternalModule(node) || compilerOptions.isolatedModules)) {
                 return node;
             }
 
@@ -74,6 +72,14 @@ namespace ts {
             return aggregateTransformFlags(updated);
         }
 
+
+        function shouldEmitUnderscoreUnderscoreESModule() {
+            if (!currentModuleInfo.exportEquals && isExternalModule(currentSourceFile)) {
+                return true;
+            }
+            return false;
+        }
+
         /**
          * Transforms a SourceFile into a CommonJS module.
          *
@@ -85,7 +91,7 @@ namespace ts {
             const statements: Statement[] = [];
             const statementOffset = addPrologueDirectives(statements, node.statements, /*ensureUseStrict*/ !compilerOptions.noImplicitUseStrict, sourceElementVisitor);
 
-            if (!currentModuleInfo.exportEquals) {
+            if (shouldEmitUnderscoreUnderscoreESModule()) {
                 append(statements, createUnderscoreUnderscoreESModule());
             }
 
@@ -378,7 +384,7 @@ namespace ts {
             const statements: Statement[] = [];
             const statementOffset = addPrologueDirectives(statements, node.statements, /*ensureUseStrict*/ !compilerOptions.noImplicitUseStrict, sourceElementVisitor);
 
-            if (!currentModuleInfo.exportEquals) {
+            if (shouldEmitUnderscoreUnderscoreESModule()) {
                 append(statements, createUnderscoreUnderscoreESModule());
             }
 

tests/baselines/reference/importHelpersInIsolatedModules.js

@@ -69,7 +69,6 @@ C = tslib_1.__decorate([
 ], C);
 //// [script.js]
 "use strict";
-Object.defineProperty(exports, "__esModule", { value: true });
 var tslib_1 = require("tslib");
 var A = (function () {
     function A() {

tests/baselines/reference/isolatedModulesPlainFile-AMD.js

@@ -7,6 +7,5 @@ run(1);
 //// [isolatedModulesPlainFile-AMD.js]
 define(["require", "exports"], function (require, exports) {
     "use strict";
-    Object.defineProperty(exports, "__esModule", { value: true });
     run(1);
 });

tests/baselines/reference/isolatedModulesPlainFile-CommonJS.js

@@ -6,5 +6,4 @@ run(1);
 
 //// [isolatedModulesPlainFile-CommonJS.js]
 "use strict";
-Object.defineProperty(exports, "__esModule", { value: true });
 run(1);

tests/baselines/reference/isolatedModulesPlainFile-UMD.js

@@ -15,6 +15,5 @@ run(1);
     }
 })(function (require, exports) {
     "use strict";
-    Object.defineProperty(exports, "__esModule", { value: true });
     run(1);
 });