fix(rsbuild-plugin): correct ESM output extension (#3870)

Author: fi3ework

packages/rsbuild-plugin/package.json

@@ -15,22 +15,22 @@
   "exports": {
     ".": {
       "types": "./dist/index.cjs.d.ts",
-      "import": "./dist/index.esm.js",
+      "import": "./dist/index.esm.mjs",
       "require": "./dist/index.cjs.js"
     },
     "./utils": {
       "types": "./dist/utils.cjs.d.ts",
-      "import": "./dist/utils.esm.js",
+      "import": "./dist/utils.esm.mjs",
       "require": "./dist/utils.cjs.js"
     },
     "./constant": {
       "types": "./dist/constant.cjs.d.ts",
-      "import": "./dist/constant.esm.js",
+      "import": "./dist/constant.esm.mjs",
       "require": "./dist/constant.cjs.js"
     }
   },
   "main": "./dist/index.cjs.js",
-  "module": "./dist/index.esm.js",
+  "module": "./dist/index.esm.mjs",
   "typesVersions": {
     "*": {
       ".": [

packages/rsbuild-plugin/rollup.config.js

@@ -16,5 +16,13 @@ module.exports = (rollupConfig, _projectOptions) => {
     utils: 'packages/rsbuild-plugin/src/utils/index.ts',
     constant: 'packages/rsbuild-plugin/src/constant.ts',
   };
+
+  rollupConfig.output.forEach((output) => {
+    output.entryFileNames = `[name].${output.format === 'esm' ? 'esm' : 'cjs'}.${
+      output.format === 'esm' ? 'mjs' : 'js'
+    }`;
+  });
+
+  // rollupConfig
   return rollupConfig;
 };