esm: add __dirname and __filename

doc/api/esm.md

@@ -308,6 +308,31 @@ modules it can be used to load ES modules.
 The `import.meta` meta property is an `Object` that contains the following
 properties.
 
+### `import.meta.__dirname`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+* {string} The directory name of the current module. This is the same as the
+  [`path.dirname()`][] of the [`import.meta.__filename`][].
+
+> **Caveat** only local modules support this property. Network modules will
+> not provide it.
+
+### `import.meta.__filename`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+* {string} The file name of the current module. This is the current module
+  file's absolute path with symlinks resolved. This is the same as the
+  [`url.fileURLToPath()`][] of the [`import.meta.url`][].
+
+> **Caveat** only local modules support this property. Network modules will
+> not provide it.
+
 ### `import.meta.url`
 
 * {string} The absolute `file:` URL of the module.
@@ -483,13 +508,6 @@ In most cases, the ES module `import` can be used to load CommonJS modules.
 If needed, a `require` function can be constructed within an ES module using
 [`module.createRequire()`][].
 
-#### No `__filename` or `__dirname`
-
-These CommonJS variables are not available in ES modules.
-
-`__filename` and `__dirname` use cases can be replicated via
-[`import.meta.url`][].
-
 #### No Addon Loading
 
 [Addons][] are not currently supported with ES module imports.
@@ -1606,17 +1624,21 @@ for ESM specifiers is [commonjs-extension-resolution-loader][].
 [`data:` URLs]: https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/Data_URIs
 [`export`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/export
 [`import()`]: #import-expressions
+[`import.meta.__dirname`]: #importmeta__dirname
+[`import.meta.__filename`]: #importmeta__filename
 [`import.meta.resolve`]: #importmetaresolvespecifier-parent
 [`import.meta.url`]: #importmetaurl
 [`import`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/import
 [`module.createRequire()`]: module.md#modulecreaterequirefilename
 [`module.register()`]: module.md#moduleregister
 [`module.syncBuiltinESMExports()`]: module.md#modulesyncbuiltinesmexports
 [`package.json`]: packages.md#nodejs-packagejson-field-definitions
+[`path.dirname()`]: path.md#dirname
 [`port.ref()`]: https://nodejs.org/dist/latest-v17.x/docs/api/worker_threads.html#portref
 [`port.unref()`]: https://nodejs.org/dist/latest-v17.x/docs/api/worker_threads.html#portunref
 [`process.dlopen`]: process.md#processdlopenmodule-filename-flags
 [`string`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String
+[`url.fileURLToPath()`]: url.md#fileurltopath
 [`util.TextDecoder`]: util.md#class-utiltextdecoder
 [cjs-module-lexer]: https://github.com/nodejs/cjs-module-lexer/tree/1.2.2
 [commonjs-extension-resolution-loader]: https://github.com/nodejs/loaders-test/tree/main/commonjs-extension-resolution-loader

lib/internal/modules/esm/initialize_import_meta.js

@@ -1,6 +1,8 @@
 'use strict';
 
 const { getOptionValue } = require('internal/options');
+const { fileURLToPath } = require('url');
+const { dirname } = require('path');
 const experimentalImportMetaResolve = getOptionValue('--experimental-import-meta-resolve');
 
 /**
@@ -32,12 +34,16 @@ function createImportMetaResolve(defaultParentUrl, loader) {
  * @param {object} meta
  * @param {{url: string}} context
  * @param {typeof import('./loader.js').ModuleLoader} loader Reference to the current module loader
- * @returns {{url: string, resolve?: Function}}
+ * @returns {{__dirname?: string, __filename?: string, url: string, resolve?: Function}}
  */
 function initializeImportMeta(meta, context, loader) {
   const { url } = context;
 
   // Alphabetical
+  const moduleMeta = resolveModuleMeta(url);
+  meta.__dirname = moduleMeta.__dirname;
+  meta.__filename = moduleMeta.__filename;
+
   if (experimentalImportMetaResolve && loader.loaderType !== 'internal') {
     meta.resolve = createImportMetaResolve(url, loader);
   }
@@ -47,6 +53,26 @@ function initializeImportMeta(meta, context, loader) {
   return meta;
 }
 
+/**
+ * Inspect the module URL and convert it to `__dirname` and `__filename`
+ * references if it does not point to a network module.
+ * @param {string} url
+ * @returns {{__dirname?: string, __filename?: string}}
+ */
+function resolveModuleMeta(url) {
+  if (url.slice(0, 7) !== 'file://') {
+    // These only make sense for locally loaded modules,
+    // i.e. network modules are not supported.
+    return { __dirname: undefined, __filename: undefined };
+  }
+
+  const filePath = fileURLToPath(url);
+  return {
+    __dirname: dirname(filePath),
+    __filename: filePath,
+  };
+}
+
 module.exports = {
   initializeImportMeta,
 };

test/es-module/test-esm-import-meta.mjs

@@ -3,7 +3,7 @@ import assert from 'assert';
 
 assert.strictEqual(Object.getPrototypeOf(import.meta), null);
 
-const keys = ['url'];
+const keys = ['__dirname', '__filename', 'url'];
 assert.deepStrictEqual(Reflect.ownKeys(import.meta), keys);
 
 const descriptors = Object.getOwnPropertyDescriptors(import.meta);
@@ -18,3 +18,9 @@ for (const descriptor of Object.values(descriptors)) {
 
 const urlReg = /^file:\/\/\/.*\/test\/es-module\/test-esm-import-meta\.mjs$/;
 assert(import.meta.url.match(urlReg));
+
+const dirReg = /^\/.*\/test\/es-module$/;
+assert(import.meta.__dirname.match(dirReg));
+
+const fileReg = /^\/.*\/test\/es-module\/test-esm-import-meta\.mjs$/;
+assert(import.meta.__filename.match(fileReg));