give .cjs ext for CommonJS files

Author: gfx

package.json

@@ -4,15 +4,15 @@
   "description": "MessagePack for ECMA-262/JavaScript/TypeScript",
   "author": "The MessagePack community",
   "license": "ISC",
-  "main": "./dist.cjs/index.js",
+  "main": "./dist.cjs/index.cjs",
   "module": "./dist.esm/index.mjs",
   "cdn": "./dist.umd/msgpack.min.js",
   "unpkg": "./dist.umd/msgpack.min.js",
   "types": "./dist.esm/index.d.ts",
   "sideEffects": false,
   "scripts": {
     "build": "npm publish --dry-run",
-    "prepare": "npm run clean && webpack --bail && tsc --build tsconfig.dist.cjs.json tsconfig.dist.esm.json && ts-node tools/esmify.ts dist.esm/*.js dist.esm/*/*.js",
+    "prepare": "npm run clean && webpack --bail && tsc --build tsconfig.dist.cjs.json tsconfig.dist.esm.json && tsimp tools/fix-ext.mts --mjs dist.esm/*.js dist.esm/*/*.js && tsimp tools/fix-ext.mts --cjs dist.cjs/*.js dist.cjs/*/*.js",
     "prepublishOnly": "npm run test:dist",
     "clean": "rimraf build dist dist.*",
     "test": "mocha 'test/**/*.test.ts'",
@@ -89,10 +89,10 @@
     "webpack-cli": "latest"
   },
   "files": [
-    "mod.ts",
     "src/**/*.*",
-    "dist/**/*.*",
+    "dist.cjs/**/*.*",
+    "dist.esm/**/*.*",
     "dist.umd/**/*.*",
-    "dist.esm/**/*.*"
+    "mod.ts"
   ]
 }

tools/esmify.ts

@@ -0,0 +1,28 @@
+import fs from "node:fs";
+
+const mode = process.argv[2]; // --cjs or --mjs
+const files = process.argv.slice(3);
+
+const ext = mode === "--cjs" ? "cjs" : "mjs";
+
+console.info(`Fixing ${mode} files with extension ${ext}`);
+
+for (const file of files) {
+  const fileMjs = file.replace(/\.js$/, `.${ext}`);
+  console.info(`Processing ${file} => ${fileMjs}`);
+  // .js => .mjs
+  const content = fs.readFileSync(file).toString("utf-8");
+  const newContent = content
+    .replace(/\bfrom "(\.\.?\/[^"]+).js";/g, `from "$1.${ext}";`)
+    .replace(/\bimport "(\.\.?\/[^"]+)";/g, 'import "$1.mjs";')
+    .replace(/\brequire\("(\.\.?\/[^"]+).js"\)/g, `require("$1.${ext}");`)
+    .replace(/\/\/# sourceMappingURL=(.+)\.js\.map$/, `//# sourceMappingURL=$1.${ext}.map`);
+  fs.writeFileSync(fileMjs, newContent);
+  fs.unlinkSync(file);
+
+  // .js.map => .mjs.map
+  const mapping = JSON.parse(fs.readFileSync(`${file}.map`).toString("utf-8"));
+  mapping.file = mapping.file.replace(/\.js$/, ext);
+  fs.writeFileSync(`${fileMjs}.map`, JSON.stringify(mapping));
+  fs.unlinkSync(`${file}.map`);
+}