fix(vite): support commonjs module.exports assignment

Author: marvinhagemeister

packages/plugin-vite/src/plugins/patches/commonjs.ts

@@ -54,6 +54,45 @@ export function cjsPlugin(
           }
 
           if (exported.size > 0 || exportedNs.size > 0) {
+            path.unshiftContainer(
+              "body",
+              t.expressionStatement(
+                t.callExpression(
+                  t.memberExpression(
+                    t.identifier("Object"),
+                    t.identifier("defineProperty"),
+                  ),
+                  [
+                    t.identifier("module"),
+                    t.stringLiteral("exports"),
+                    t.objectExpression([
+                      t.objectMethod(
+                        "method",
+                        t.identifier("get"),
+                        [],
+                        t.blockStatement([
+                          t.returnStatement(t.identifier("exports")),
+                        ]),
+                      ),
+                      t.objectMethod(
+                        "method",
+                        t.identifier("set"),
+                        [t.identifier("value")],
+                        t.blockStatement([
+                          t.expressionStatement(
+                            t.assignmentExpression(
+                              "=",
+                              t.identifier("exports"),
+                              t.identifier("value"),
+                            ),
+                          ),
+                        ]),
+                      ),
+                    ]),
+                  ],
+                ),
+              ),
+            );
             path.unshiftContainer(
               "body",
               t.variableDeclaration("var", [
@@ -63,14 +102,7 @@ export function cjsPlugin(
                 ),
                 t.variableDeclarator(
                   t.identifier("module"),
-                  t.objectExpression([
-                    t.objectProperty(
-                      t.identifier("exports"),
-                      t.identifier("exports"),
-                      false,
-                      true,
-                    ),
-                  ]),
+                  t.objectExpression([]),
                 ),
               ]),
             );
@@ -124,24 +156,11 @@ export function cjsPlugin(
                   id,
                   t.logicalExpression(
                     "??",
-                    t.logicalExpression(
-                      "??",
-                      t.memberExpression(
-                        t.memberExpression(
-                          t.identifier("module"),
-                          t.identifier("exports"),
-                        ),
-                        t.identifier("default"),
-                      ),
-                      t.memberExpression(
-                        t.identifier("exports"),
-                        t.identifier("default"),
-                      ),
-                    ),
                     t.memberExpression(
-                      t.identifier("module"),
                       t.identifier("exports"),
+                      t.identifier("default"),
                     ),
+                    t.identifier("exports"),
                   ),
                 ),
               ]),

packages/plugin-vite/src/plugins/patches/commonjs_test.ts

@@ -14,12 +14,17 @@ function runTest(options: { input: string; expected: string }) {
 }
 
 const INIT = `var exports = {},
-  module = {
-    exports
-  };`;
+  module = {};
+Object.defineProperty(module, "exports", {
+  get() {
+    return exports;
+  },
+  set(value) {
+    exports = value;
+  }
+});`;
 
-const DEFAULT_EXPORT =
-  `const _default = module.exports.default ?? exports.default ?? module.exports;`;
+const DEFAULT_EXPORT = `const _default = exports.default ?? exports;`;
 const DEFAULT_EXPORT_END = `export default _default;`;
 
 Deno.test("commonjs - module.exports default", () => {
@@ -451,3 +456,18 @@ Object.assign(_default, _ns);
 ${DEFAULT_EXPORT_END}`,
   });
 });
+
+Deno.test("commonjs - assign module.exports", () => {
+  runTest({
+    input: `module.exports = { foo: 1 };`,
+    expected: `${INIT}
+module.exports = {
+  foo: 1
+};
+var _foo = exports.foo;
+export { _foo as foo };
+${DEFAULT_EXPORT}
+_default.foo = _foo;
+${DEFAULT_EXPORT_END}`,
+  });
+});