[infra] Remove package.json module field (#46620)

Author: Janpot

docs/data/material/guides/minimizing-bundle-size/minimizing-bundle-size.md

@@ -67,3 +67,16 @@ To prevent VS Code from automatically importing from `@mui/material`, you can u
 ## Using Next.js 13.5 or later?
 
 If you're on **Next.js 13.5 or newer**, you're in good hands. These versions include automatic import optimization via the `optimizePackageImports` option. This removes the need for manual configuration or Babel plugins to optimize imports.
+
+## Using parcel
+
+Parcel, by default, doesn't resolve package.json `"exports"`. This makes it always resolve to the commonjs version of our library. To make it optimally make use of our ESM version, make sure to [enable the `packageExports` option](https://parceljs.org/features/dependency-resolution/#enabling-package-exports).
+
+```json
+// ./package.json
+{
+  "@parcel/resolver-default": {
+    "packageExports": true
+  }
+}
+```

scripts/copyFilesUtils.mjs

@@ -138,8 +138,7 @@ function createExportFor(exportName, conditions) {
   };
 }
 
-// TODO: remove useEsmExports paramater once X is on the ESM-exports package layout (default to true)
-export async function createPackageFile(useEsmExports = false) {
+export async function createPackageFile() {
   const packageData = await fse.readFile(path.resolve(packagePath, './package.json'), 'utf8');
   const { nyc, scripts, devDependencies, workspaces, ...packageDataOther } =
     JSON.parse(packageData);
@@ -170,32 +169,12 @@ export async function createPackageFile(useEsmExports = false) {
     }
   }
 
-  const newPackageData = useEsmExports
-    ? {
-        ...packageDataOther,
-        private: false,
-        ...(packageDataOther.main
-          ? {
-              main: './index.js',
-              module: './esm/index.js',
-            }
-          : {}),
-        exports: packageExports,
-      }
-    : {
-        ...packageDataOther,
-        private: false,
-        ...(packageDataOther.main
-          ? {
-              main: fse.existsSync(path.resolve(buildPath, './node/index.js'))
-                ? './node/index.js'
-                : './index.js',
-              module: fse.existsSync(path.resolve(buildPath, './esm/index.js'))
-                ? './esm/index.js'
-                : './index.js',
-            }
-          : {}),
-      };
+  const newPackageData = {
+    ...packageDataOther,
+    private: false,
+    ...(packageDataOther.main ? { main: './index.js' } : {}),
+    exports: packageExports,
+  };
 
   const typeDefinitionsFilePath = path.resolve(buildPath, './index.d.ts');
   if (await fse.pathExists(typeDefinitionsFilePath)) {