esm: module.exports on CJS modules

Author: guybedford

lib/internal/modules/esm/translators.js

@@ -188,10 +188,13 @@ function createCJSModuleWrap(url, source, isMain, format, loadCJS = loadCJSModul
   const { exportNames, module } = cjsPreparseModuleExports(filename, source, format);
   cjsCache.set(url, module);
 
-  const wrapperNames = [...exportNames, 'module.exports'];
+  const wrapperNames = [...exportNames];
   if (!exportNames.has('default')) {
     ArrayPrototypePush(wrapperNames, 'default');
   }
+  if (!exportNames.has('module.exports')) {
+    ArrayPrototypePush(wrapperNames, 'module.exports');
+  }
 
   if (isMain) {
     setOwnProperty(process, 'mainModule', module);
@@ -212,7 +215,8 @@ function createCJSModuleWrap(url, source, isMain, format, loadCJS = loadCJSModul
       ({ exports } = module);
     }
     for (const exportName of exportNames) {
-      if (!ObjectPrototypeHasOwnProperty(exports, exportName) || exportName === 'default') {
+      if (exportName === 'default' || exportName === 'module.exports' ||
+          !ObjectPrototypeHasOwnProperty(exports, exportName)) {
         continue;
       }
       // We might trigger a getter -> dont fail.

test/fixtures/es-modules/exports-cases.js

@@ -1,9 +1,10 @@
-if (global.maybe)
-  module.exports = require('../is-object');
-exports['invalid identifier'] = 'yes';
-module.exports['?invalid'] = 'yes';
-module.exports['π'] = 'yes';
-exports['\u{D83C}'] = 'no';
-exports['\u{D83C}\u{DF10}'] = 'yes';
-exports.package  = 10; // reserved word
-Object.defineProperty(exports, 'z', { value: 'yes' });
+if (global.maybe)
+  module.exports = require('../is-object');
+exports['invalid identifier'] = 'yes';
+module.exports['?invalid'] = 'yes';
+module.exports['π'] = 'yes';
+exports['\u{D83C}'] = 'no';
+exports['\u{D83C}\u{DF10}'] = 'yes';
+exports.package  = 10; // reserved word
+Object.defineProperty(exports, 'z', { value: 'yes' });
+exports['module.exports'] = 5;