fix: improve esMododule exports

README.md

@@ -407,6 +407,7 @@ module.exports = {
 - **[`publicPath`](#publicPath)**
 - **[`emit`](#emit)**
 - **[`esModule`](#esModule)**
+- **[`defaultExport`](#defaultExport)**
 
 #### `publicPath`
 
@@ -549,6 +550,60 @@ module.exports = {
 };
 ```
 
+#### `defaultExport`
+
+Type:
+
+```ts
+type defaultExport = boolean;
+```
+
+Default: `false`
+
+> **Note**
+>
+> This option will work only when you set `namedExport` to `true` in `css-loader`
+
+By default, `mini-css-extract-plugin` generates JS modules based on the `esModule` and `namedExport` options in `css-loader`.
+Using the `esModule` and `namedExport` options will allow you to better optimize your code.
+If you set `esModule: true` and `namedExport: true` for `css-loader` `mini-css-extract-plugin` will generate **only** a named export.
+Our official recommendation is to use only named export for better future compatibility.
+But for some applications, it is not easy to quickly rewrite the code from the default export to a named export.
+
+In case you need both default and named exports, you can enable this option:
+
+**webpack.config.js**
+
+```js
+const MiniCssExtractPlugin = require("mini-css-extract-plugin");
+
+module.exports = {
+  plugins: [new MiniCssExtractPlugin()],
+  module: {
+    rules: [
+      {
+        test: /\.css$/i,
+        use: [
+          {
+            loader: MiniCssExtractPlugin.loader,
+            options: {
+              defaultExport: true,
+            },
+          },
+          {
+            loader: "css-loader",
+            esModule: true,
+            modules: {
+              namedExport: true,
+            },
+          },
+        ],
+      },
+    ],
+  },
+};
+```
+
 ## Examples
 
 ### Recommended

src/index.js

@@ -37,6 +37,7 @@ const {
  * @property {boolean} [emit]
  * @property {boolean} [esModule]
  * @property {string} [layer]
+ * @property {boolean} [defaultExport]
  */
 
 /**

src/loader-options.json

@@ -27,6 +27,11 @@
     },
     "layer": {
       "type": "string"
+    },
+    "defaultExport": {
+      "type": "boolean",
+      "description": "Duplicate the named export with CSS modules locals to the default export (only when `esModules: true` for css-loader).",
+      "link": "https://github.com/webpack-contrib/mini-css-extract-plugin#defaultexports"
     }
   }
 }

src/loader.js

@@ -272,7 +272,16 @@ function pitch(request) {
             .map(([id, key]) => `${id} as ${JSON.stringify(key)}`)
             .join(", ")} }`;
 
-          return `${localsString}\n${exportsString}\n`;
+          const defaultExport =
+            typeof options.defaultExport !== "undefined"
+              ? options.defaultExport
+              : false;
+
+          return defaultExport
+            ? `${localsString}\n${exportsString}\nexport default { ${identifiers
+                .map(([id, key]) => `${JSON.stringify(key)}: ${id}`)
+                .join(", ")} }\n`
+            : `${localsString}\n${exportsString}\n`;
         }
 
         return `\n${

test/__snapshots__/validate-loader-options.test.js.snap

@@ -1,5 +1,12 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
+exports[`validate options should throw an error on the "defaultExport" option with "1" value 1`] = `
+"Invalid options object. Mini CSS Extract Plugin Loader has been initialized using an options object that does not match the API schema.
+ - options.defaultExport should be a boolean.
+   -> Duplicate the named export with CSS modules locals to the default export (only when \`esModules: true\` for css-loader).
+   -> Read more at https://github.com/webpack-contrib/mini-css-extract-plugin#defaultexports"
+`;
+
 exports[`validate options should throw an error on the "esModule" option with "1" value 1`] = `
 "Invalid options object. Mini CSS Extract Plugin Loader has been initialized using an options object that does not match the API schema.
  - options.esModule should be a boolean.
@@ -21,47 +28,47 @@ exports[`validate options should throw an error on the "publicPath" option with
 exports[`validate options should throw an error on the "unknown" option with "/test/" value 1`] = `
 "Invalid options object. Mini CSS Extract Plugin Loader has been initialized using an options object that does not match the API schema.
  - options has an unknown property 'unknown'. These properties are valid:
-   object { publicPath?, emit?, esModule?, layer? }"
+   object { publicPath?, emit?, esModule?, layer?, defaultExport? }"
 `;
 
 exports[`validate options should throw an error on the "unknown" option with "[]" value 1`] = `
 "Invalid options object. Mini CSS Extract Plugin Loader has been initialized using an options object that does not match the API schema.
  - options has an unknown property 'unknown'. These properties are valid:
-   object { publicPath?, emit?, esModule?, layer? }"
+   object { publicPath?, emit?, esModule?, layer?, defaultExport? }"
 `;
 
 exports[`validate options should throw an error on the "unknown" option with "{"foo":"bar"}" value 1`] = `
 "Invalid options object. Mini CSS Extract Plugin Loader has been initialized using an options object that does not match the API schema.
  - options has an unknown property 'unknown'. These properties are valid:
-   object { publicPath?, emit?, esModule?, layer? }"
+   object { publicPath?, emit?, esModule?, layer?, defaultExport? }"
 `;
 
 exports[`validate options should throw an error on the "unknown" option with "{}" value 1`] = `
 "Invalid options object. Mini CSS Extract Plugin Loader has been initialized using an options object that does not match the API schema.
  - options has an unknown property 'unknown'. These properties are valid:
-   object { publicPath?, emit?, esModule?, layer? }"
+   object { publicPath?, emit?, esModule?, layer?, defaultExport? }"
 `;
 
 exports[`validate options should throw an error on the "unknown" option with "1" value 1`] = `
 "Invalid options object. Mini CSS Extract Plugin Loader has been initialized using an options object that does not match the API schema.
  - options has an unknown property 'unknown'. These properties are valid:
-   object { publicPath?, emit?, esModule?, layer? }"
+   object { publicPath?, emit?, esModule?, layer?, defaultExport? }"
 `;
 
 exports[`validate options should throw an error on the "unknown" option with "false" value 1`] = `
 "Invalid options object. Mini CSS Extract Plugin Loader has been initialized using an options object that does not match the API schema.
  - options has an unknown property 'unknown'. These properties are valid:
-   object { publicPath?, emit?, esModule?, layer? }"
+   object { publicPath?, emit?, esModule?, layer?, defaultExport? }"
 `;
 
 exports[`validate options should throw an error on the "unknown" option with "test" value 1`] = `
 "Invalid options object. Mini CSS Extract Plugin Loader has been initialized using an options object that does not match the API schema.
  - options has an unknown property 'unknown'. These properties are valid:
-   object { publicPath?, emit?, esModule?, layer? }"
+   object { publicPath?, emit?, esModule?, layer?, defaultExport? }"
 `;
 
 exports[`validate options should throw an error on the "unknown" option with "true" value 1`] = `
 "Invalid options object. Mini CSS Extract Plugin Loader has been initialized using an options object that does not match the API schema.
  - options has an unknown property 'unknown'. These properties are valid:
-   object { publicPath?, emit?, esModule?, layer? }"
+   object { publicPath?, emit?, esModule?, layer?, defaultExport? }"
 `;

test/cases/es-named-and-default-export/expected/main.css

@@ -0,0 +1,12 @@
+.foo__style__a-class {
+  background: red;
+}
+
+.foo__style__b__class {
+  color: green;
+}
+
+.foo__style__cClass {
+  color: blue;
+}
+

test/cases/es-named-and-default-export/expected/main.js

@@ -0,0 +1,93 @@
+/******/ (() => { // webpackBootstrap
+/******/ 	"use strict";
+/******/ 	var __webpack_modules__ = ([
+/* 0 */,
+/* 1 */
+/***/ ((__unused_webpack_module, __webpack_exports__, __webpack_require__) => {
+
+__webpack_require__.r(__webpack_exports__);
+/* harmony export */ __webpack_require__.d(__webpack_exports__, {
+/* harmony export */   "a-class": () => (/* binding */ _1),
+/* harmony export */   b__class: () => (/* binding */ _2),
+/* harmony export */   cClass: () => (/* binding */ _3),
+/* harmony export */   "default": () => (__WEBPACK_DEFAULT_EXPORT__)
+/* harmony export */ });
+// extracted by mini-css-extract-plugin
+var _1 = "foo__style__a-class";
+var _2 = "foo__style__b__class";
+var _3 = "foo__style__cClass";
+
+/* harmony default export */ const __WEBPACK_DEFAULT_EXPORT__ = ({ "a-class": _1, "b__class": _2, "cClass": _3 });
+
+
+/***/ })
+/******/ 	]);
+/************************************************************************/
+/******/ 	// The module cache
+/******/ 	var __webpack_module_cache__ = {};
+/******/ 	
+/******/ 	// The require function
+/******/ 	function __webpack_require__(moduleId) {
+/******/ 		// Check if module is in cache
+/******/ 		var cachedModule = __webpack_module_cache__[moduleId];
+/******/ 		if (cachedModule !== undefined) {
+/******/ 			return cachedModule.exports;
+/******/ 		}
+/******/ 		// Create a new module (and put it into the cache)
+/******/ 		var module = __webpack_module_cache__[moduleId] = {
+/******/ 			// no module.id needed
+/******/ 			// no module.loaded needed
+/******/ 			exports: {}
+/******/ 		};
+/******/ 	
+/******/ 		// Execute the module function
+/******/ 		__webpack_modules__[moduleId](module, module.exports, __webpack_require__);
+/******/ 	
+/******/ 		// Return the exports of the module
+/******/ 		return module.exports;
+/******/ 	}
+/******/ 	
+/************************************************************************/
+/******/ 	/* webpack/runtime/define property getters */
+/******/ 	(() => {
+/******/ 		// define getter functions for harmony exports
+/******/ 		__webpack_require__.d = (exports, definition) => {
+/******/ 			for(var key in definition) {
+/******/ 				if(__webpack_require__.o(definition, key) && !__webpack_require__.o(exports, key)) {
+/******/ 					Object.defineProperty(exports, key, { enumerable: true, get: definition[key] });
+/******/ 				}
+/******/ 			}
+/******/ 		};
+/******/ 	})();
+/******/ 	
+/******/ 	/* webpack/runtime/hasOwnProperty shorthand */
+/******/ 	(() => {
+/******/ 		__webpack_require__.o = (obj, prop) => (Object.prototype.hasOwnProperty.call(obj, prop))
+/******/ 	})();
+/******/ 	
+/******/ 	/* webpack/runtime/make namespace object */
+/******/ 	(() => {
+/******/ 		// define __esModule on exports
+/******/ 		__webpack_require__.r = (exports) => {
+/******/ 			if(typeof Symbol !== 'undefined' && Symbol.toStringTag) {
+/******/ 				Object.defineProperty(exports, Symbol.toStringTag, { value: 'Module' });
+/******/ 			}
+/******/ 			Object.defineProperty(exports, '__esModule', { value: true });
+/******/ 		};
+/******/ 	})();
+/******/ 	
+/************************************************************************/
+var __webpack_exports__ = {};
+// This entry need to be wrapped in an IIFE because it need to be isolated against other modules in the chunk.
+(() => {
+__webpack_require__.r(__webpack_exports__);
+/* harmony import */ var _style_css__WEBPACK_IMPORTED_MODULE_0__ = __webpack_require__(1);
+
+
+// eslint-disable-next-line no-console
+console.log({ css: _style_css__WEBPACK_IMPORTED_MODULE_0__["default"], aClass: _style_css__WEBPACK_IMPORTED_MODULE_0__["a-class"], bClass: _style_css__WEBPACK_IMPORTED_MODULE_0__.b__class, cClass: _style_css__WEBPACK_IMPORTED_MODULE_0__.cClass });
+
+})();
+
+/******/ })()
+;

test/cases/es-named-and-default-export/index.js

@@ -0,0 +1,8 @@
+import css, {
+  "a-class" as aClass,
+  "b__class" as bClass,
+  cClass,
+} from "./style.css";
+
+// eslint-disable-next-line no-console
+console.log({ css, aClass, bClass, cClass });

test/cases/es-named-and-default-export/style.css

@@ -0,0 +1,11 @@
+.a-class {
+  background: red;
+}
+
+.b__class {
+  color: green;
+}
+
+.cClass {
+  color: blue;
+}

test/cases/es-named-and-default-export/webpack.config.js

@@ -0,0 +1,36 @@
+import Self from "../../../src";
+
+module.exports = {
+  entry: "./index.js",
+  module: {
+    rules: [
+      {
+        test: /\.css$/,
+        use: [
+          {
+            loader: Self.loader,
+            options: {
+              defaultExport: true,
+            },
+          },
+          {
+            loader: "css-loader",
+            options: {
+              esModule: true,
+              modules: {
+                namedExport: true,
+                exportLocalsConvention: "asIs",
+                localIdentName: "foo__[name]__[local]",
+              },
+            },
+          },
+        ],
+      },
+    ],
+  },
+  plugins: [
+    new Self({
+      filename: "[name].css",
+    }),
+  ],
+};

test/validate-loader-options.test.js

@@ -10,6 +10,10 @@ describe("validate options", () => {
       success: [true, false],
       failure: [1],
     },
+    defaultExport: {
+      success: [true, false],
+      failure: [1],
+    },
     unknown: {
       success: [],
       failure: [1, true, false, "test", /test/, [], {}, { foo: "bar" }],

types/index.d.ts

@@ -148,6 +148,7 @@ type PluginOptions = {
  * @property {boolean} [emit]
  * @property {boolean} [esModule]
  * @property {string} [layer]
+ * @property {boolean} [defaultExport]
  */
 /**
  * @typedef {Object} PluginOptions
@@ -200,6 +201,7 @@ type LoaderOptions = {
   emit?: boolean | undefined;
   esModule?: boolean | undefined;
   layer?: string | undefined;
+  defaultExport?: boolean | undefined;
 };
 type NormalizedPluginOptions = {
   filename: Required<Configuration>["output"]["filename"];