Add CommonJS Backward compatibility entry points

README.md

@@ -25,6 +25,9 @@ The [`music-metadata`](https://github.com/Borewit/music-metadata) module is idea
 Module: version 8 migrated from [CommonJS](https://en.wikipedia.org/wiki/CommonJS) to [pure ECMAScript Module (ESM)](https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c).
 The distributed JavaScript codebase is compliant with the [ECMAScript 2020 (11th Edition)](https://en.wikipedia.org/wiki/ECMAScript_version_history#11th_Edition_%E2%80%93_ECMAScript_2020) standard.
 
+> [!NOTE]
+> See also [CommonJS Backward Compatibility](#commonjs-backward-compatibility)
+
 This module requires a [Node.js ≥ 16](https://nodejs.org/en/about/previous-releases) engine.
 It can also be used in a browser environment when bundled with a module bundler.
 
@@ -764,6 +767,23 @@ Dependency list:
 - [@tokenizer-token](https://github.com/Borewit/tokenizer-token)
 - [peek-readable](https://github.com/Borewit/peek-readable)
 
+## CommonJS Backward compatibility
+
+For legacy CommonJS projects needing to load the `music-metadata` ESM module, you can use the `loadMusicMetadata` function:
+```js
+const { loadMusicMetadata } = require('music-metadata');
+
+(async () => {
+  // Dynamically loads the ESM module in a CommonJS project
+  const mm = await loadMusicMetadata();
+
+  const metadata = await mm.parseFile('/path/to/your/file');
+})();
+
+```
+
+> [!NOTE]
+> The `loadMusicMetadata` function is experimental and is not currently covered by any TypeScript typings.
 
 ## Frequently Asked Questions
 

lib/default.cjs

@@ -0,0 +1,5 @@
+// CommonJS core (default) entry point
+"use strict";
+module.exports = {
+  loadMusicMetadata: () => import('./core.js'),
+};

lib/node.cjs

@@ -0,0 +1,5 @@
+// CommonJS Node entry point
+"use strict";
+module.exports = {
+  loadMusicMetadata: () => import('./index.js'),
+};

package.json

@@ -19,14 +19,23 @@
   "type": "module",
   "exports": {
     ".": {
-      "node": "./lib/index.js",
-      "default": "./lib/core.js"
+      "node": {
+        "import": "./lib/index.js",
+        "require": "./lib/node.cjs",
+        "types": "./lib/index.d.ts"
+      },
+      "default": {
+        "import": "./lib/core.js",
+        "require": "./lib/default.cjs",
+        "types": "./lib/core.d.ts"
+      }
     }
   },
   "types": "lib/index.d.ts",
   "files": [
     "lib/**/*.js",
-    "lib/**/*.d.ts"
+    "lib/**/*.d.ts",
+    "lib/*.cjs"
   ],
   "keywords": [
     "music",