change the output file structure and extension

Author: NShahri

package.json

@@ -17,9 +17,9 @@
     "url": "http://github.com/graphql/dataloader.git"
   },
   "type": "module",
-  "main": "dist/cjs/index.js",
-  "module": "dist/esm/index.js",
-  "typings": "dist/esm/index.d.ts",
+  "main": "dist/index.js",
+  "module": "dist/index.mjs",
+  "typings": "dist/index.d.ts",
   "scripts": {
     "test": "npm run lint && npm run check && npm run testonly",
     "test:ci": "npm run lint && npm run check && npm run testonly -- --coverage",
@@ -28,6 +28,7 @@
     "build:esm": "tsc -p tsconfig.esm.json",
     "build:cjs": "tsc -p tsconfig.cjs.json",
     "build": "npm run build:esm && npm run build:cjs",
+    "postbuild": "node --experimental-strip-types ./post-build.ts",
     "watch": "node --watch-path=src --experimental-strip-types src/index.ts",
     "testonly": "NODE_OPTIONS=\"$NODE_OPTIONS --experimental-vm-modules\" jest ",
     "prerelease": ". ./resources/prepublish.sh",

post-build.ts

@@ -0,0 +1,38 @@
+import { readdirSync, renameSync, rmSync } from 'fs';
+import { join, basename } from 'path';
+
+function removeAllFiles(dirPath: string) {
+  const files = readdirSync(dirPath, { withFileTypes: true })
+    .filter(f => f.isFile())
+    .map(f => join(f.parentPath, f.name));
+  files.forEach(file => {
+    rmSync(file, { recursive: true, force: true });
+  });
+}
+
+function moveAndRename(srcDir: string, destDir: string, newExt: string) {
+  const files = readdirSync(srcDir, { withFileTypes: true })
+    .filter(f => f.isFile())
+    .map(f => join(f.parentPath, f.name));
+  files.forEach(file => {
+    const destFilePath = join(
+      destDir,
+      basename(file)
+        .replace(/\.js\.map$/, `${newExt}.map`)
+        .replace(/\.js$/, newExt),
+    );
+
+    renameSync(file, destFilePath);
+    console.log(`Moved and renamed: ${file} -> ${destFilePath}`);
+  });
+
+  rmSync(srcDir, { recursive: true, force: true });
+}
+
+const srcDirCjs = join(import.meta.dirname, './dist/cjs');
+const srcDirEsm = join(import.meta.dirname, './dist/esm');
+const destDir = join(import.meta.dirname, './dist');
+
+removeAllFiles(destDir);
+moveAndRename(srcDirCjs, destDir, '.js');
+moveAndRename(srcDirEsm, destDir, '.mjs');