diff --git a/lib/internal/dns/promises.js b/lib/internal/dns/promises.js
index 79be8591bbcad2..1169b2735d4efe 100644
--- a/lib/internal/dns/promises.js
+++ b/lib/internal/dns/promises.js
@@ -113,6 +113,19 @@ function onlookupall(err, addresses) {
   }
 }
 
+/**
+ * Creates a promise that resolves with the IP address of the given hostname.
+ * @param {0 | 4 | 6} family - The IP address family (4 or 6, or 0 for both).
+ * @param {string} hostname - The hostname to resolve.
+ * @param {boolean} all - Whether to resolve with all IP addresses for the hostname.
+ * @param {number} hints - One or more supported getaddrinfo flags (supply multiple via
+ * bitwise OR).
+ * @param {boolean} verbatim - Whether to use the hostname verbatim.
+ * @returns {Promise<DNSLookupResult | DNSLookupResult[]>} The IP address(es) of the hostname.
+ * @typedef {object} DNSLookupResult
+ * @property {string} address - The IP address.
+ * @property {0 | 4 | 6} family - The IP address type. 4 for IPv4 or 6 for IPv6, or 0 (for both).
+ */
 function createLookupPromise(family, hostname, all, hints, verbatim) {
   return new Promise((resolve, reject) => {
     if (!hostname) {
@@ -154,6 +167,17 @@ function createLookupPromise(family, hostname, all, hints, verbatim) {
 }
 
 const validFamilies = [0, 4, 6];
+/**
+ * Get the IP address for a given hostname.
+ * @param {string} hostname - The hostname to resolve (ex. 'nodejs.org').
+ * @param {object} [options] - Optional settings.
+ * @param {boolean} [options.all=false] - Whether to return all or just the first resolved address.
+ * @param {0 | 4 | 6} [options.family=0] - The record family. Must be 4, 6, or 0 (for both).
+ * @param {number} [options.hints] - One or more supported getaddrinfo flags (supply multiple via
+ * bitwise OR).
+ * @param {boolean} [options.verbatim=false] - Return results in same order DNS resolved them;
+ * otherwise IPv4 then IPv6. New code should supply `true`.
+ */
 function lookup(hostname, options) {
   let hints = 0;
   let family = 0;
diff --git a/lib/internal/modules/cjs/loader.js b/lib/internal/modules/cjs/loader.js
index 108d2b7ffbd5de..db31feb93ee724 100644
--- a/lib/internal/modules/cjs/loader.js
+++ b/lib/internal/modules/cjs/loader.js
@@ -155,6 +155,11 @@ let requireDepth = 0;
 let isPreloading = false;
 let statCache = null;
 
+/**
+ * Our internal implementation of `require`.
+ * @param {Module} module Parent module of what is being required
+ * @param {string} id Specifier of the child module being imported
+ */
 function internalRequire(module, id) {
   validateString(id, 'id');
   if (id === '') {
@@ -169,6 +174,10 @@ function internalRequire(module, id) {
   }
 }
 
+/**
+ * Get a path's properties, using an in-memory cache to minimize lookups.
+ * @param {string} filename Absolute path to the file
+ */
 function stat(filename) {
   filename = path.toNamespacedPath(filename);
   if (statCache !== null) {
@@ -195,6 +204,12 @@ ObjectDefineProperty(Module, '_stat', {
   configurable: true,
 });
 
+/**
+ * Update the parent's children array with the child module.
+ * @param {Module} parent Module requiring the children
+ * @param {Module} child Module being required
+ * @param {boolean} scan Add the child to the parent's children if not already present
+ */
 function updateChildren(parent, child, scan) {
   const children = parent?.children;
   if (children && !(scan && ArrayPrototypeIncludes(children, child))) {
@@ -202,19 +217,34 @@ function updateChildren(parent, child, scan) {
   }
 }
 
+/**
+ * Tell the watch mode that a module was required.
+ * @param {string} filename Absolute path of the module
+ */
 function reportModuleToWatchMode(filename) {
   if (shouldReportRequiredModules() && process.send) {
     process.send({ 'watch:require': [filename] });
   }
 }
 
+/**
+ * Tell the watch mode that a module was not found.
+ * @param {string} basePath The absolute path that errored
+ * @param {string[]} extensions The extensions that were tried
+ */
 function reportModuleNotFoundToWatchMode(basePath, extensions) {
   if (shouldReportRequiredModules() && process.send) {
     process.send({ 'watch:require': ArrayPrototypeMap(extensions, (ext) => path.resolve(`${basePath}${ext}`)) });
   }
 }
 
+/** @type {Map<Module, Module>} */
 const moduleParentCache = new SafeWeakMap();
+/**
+ * Create a new module instance.
+ * @param {string} id
+ * @param {Module} parent
+ */
 function Module(id = '', parent) {
   this.id = id;
   this.path = path.dirname(id);
@@ -237,16 +267,24 @@ function Module(id = '', parent) {
   this[require_private_symbol] = internalRequire;
 }
 
+/** @type {Record<string, Module>} */
 Module._cache = { __proto__: null };
+/** @type {Record<string, string>} */
 Module._pathCache = { __proto__: null };
+/** @type {Record<string, (module: Module, filename: string) => void>} */
 Module._extensions = { __proto__: null };
+/** @type {string[]} */
 let modulePaths = [];
+/** @type {string[]} */
 Module.globalPaths = [];
 
 let patched = false;
 
-// eslint-disable-next-line func-style
-let wrap = function(script) {
+/**
+ * Add the CommonJS wrapper around a module's source code.
+ * @param {string} script Module source code
+ */
+let wrap = function(script) { // eslint-disable-line func-style
   return Module.wrapper[0] + script + Module.wrapper[1];
 };
 
@@ -297,10 +335,17 @@ const isPreloadingDesc = { get() { return isPreloading; } };
 ObjectDefineProperty(Module.prototype, 'isPreloading', isPreloadingDesc);
 ObjectDefineProperty(BuiltinModule.prototype, 'isPreloading', isPreloadingDesc);
 
+/**
+ * Get the parent of the current module from our cache.
+ */
 function getModuleParent() {
   return moduleParentCache.get(this);
 }
 
+/**
+ * Set the parent of the current module in our cache.
+ * @param {Module} value
+ */
 function setModuleParent(value) {
   moduleParentCache.set(this, value);
 }
@@ -327,7 +372,10 @@ ObjectDefineProperty(Module.prototype, 'parent', {
 Module._debug = pendingDeprecate(debug, 'Module._debug is deprecated.', 'DEP0077');
 Module.isBuiltin = BuiltinModule.isBuiltin;
 
-// This function is called during pre-execution, before any user code is run.
+/**
+ * Prepare to run CommonJS code.
+ * This function is called during pre-execution, before any user code is run.
+ */
 function initializeCJS() {
   // This need to be done at runtime in case --expose-internals is set.
   const builtinModules = BuiltinModule.getCanBeRequiredByUsersWithoutSchemeList();
@@ -375,6 +423,11 @@ ObjectDefineProperty(Module, '_readPackage', {
   configurable: true,
 });
 
+/**
+ * Get the nearest parent package.json file from a given path.
+ * Return the package.json data and the path to the package.json file, or false.
+ * @param {string} checkPath The path to start searching from.
+ */
 function readPackageScope(checkPath) {
   const rootSeparatorIndex = StringPrototypeIndexOf(checkPath, sep);
   let separatorIndex;
@@ -401,6 +454,13 @@ function readPackageScope(checkPath) {
   return false;
 }
 
+/**
+ * Try to load a specifier as a package.
+ * @param {string} requestPath The path to what we are trying to load
+ * @param {string[]} exts File extensions to try appending in order to resolve the file
+ * @param {boolean} isMain Whether the file is the main entry point of the app
+ * @param {string} originalPath The specifier passed to `require`
+ */
 function tryPackage(requestPath, exts, isMain, originalPath) {
   const pkg = _readPackage(requestPath).main;
 
@@ -438,15 +498,20 @@ function tryPackage(requestPath, exts, isMain, originalPath) {
   return actual;
 }
 
-// In order to minimize unnecessary lstat() calls,
-// this cache is a list of known-real paths.
-// Set to an empty Map to reset.
+/**
+ * Cache for storing resolved real paths of modules.
+ * In order to minimize unnecessary lstat() calls, this cache is a list of known-real paths.
+ * Set to an empty Map to reset.
+ * @type {Map<string, string>}
+ */
 const realpathCache = new SafeMap();
 
-// Check if the file exists and is not a directory
-// if using --preserve-symlinks and isMain is false,
-// keep symlinks intact, otherwise resolve to the
-// absolute realpath.
+/**
+ * Check if the file exists and is not a directory if using `--preserve-symlinks` and `isMain` is false, keep symlinks
+ * intact, otherwise resolve to the absolute realpath.
+ * @param {string} requestPath The path to the file to load.
+ * @param {boolean} isMain Whether the file is the main module.
+ */
 function tryFile(requestPath, isMain) {
   const rc = _stat(requestPath);
   if (rc !== 0) { return; }
@@ -456,16 +521,26 @@ function tryFile(requestPath, isMain) {
   return toRealPath(requestPath);
 }
 
+
+/**
+ * Resolves the path of a given `require` specifier, following symlinks.
+ * @param {string} requestPath The `require` specifier
+ */
 function toRealPath(requestPath) {
   return fs.realpathSync(requestPath, {
     [internalFS.realpathCacheKey]: realpathCache,
   });
 }
 
-// Given a path, check if the file exists with any of the set extensions
-function tryExtensions(p, exts, isMain) {
+/**
+ * Given a path, check if the file exists with any of the set extensions.
+ * @param {string} basePath The path and filename without extension
+ * @param {string[]} exts The extensions to try
+ * @param {boolean} isMain Whether the module is the main module
+ */
+function tryExtensions(basePath, exts, isMain) {
   for (let i = 0; i < exts.length; i++) {
-    const filename = tryFile(p + exts[i], isMain);
+    const filename = tryFile(basePath + exts[i], isMain);
 
     if (filename) {
       return filename;
@@ -474,8 +549,10 @@ function tryExtensions(p, exts, isMain) {
   return false;
 }
 
-// Find the longest (possibly multi-dot) extension registered in
-// Module._extensions
+/**
+ * Find the longest (possibly multi-dot) extension registered in `Module._extensions`.
+ * @param {string} filename The filename to find the longest registered extension for.
+ */
 function findLongestRegisteredExtension(filename) {
   const name = path.basename(filename);
   let currentExtension;
@@ -490,6 +567,10 @@ function findLongestRegisteredExtension(filename) {
   return '.js';
 }
 
+/**
+ * Tries to get the absolute file path of the parent module.
+ * @param {Module} parent The parent module object.
+ */
 function trySelfParentPath(parent) {
   if (!parent) { return false; }
 
@@ -504,6 +585,11 @@ function trySelfParentPath(parent) {
   }
 }
 
+/**
+ * Attempt to resolve a module request using the parent module package metadata.
+ * @param {string} parentPath The path of the parent module
+ * @param {string} request The module request to resolve
+ */
 function trySelf(parentPath, request) {
   if (!parentPath) { return false; }
 
@@ -534,10 +620,18 @@ function trySelf(parentPath, request) {
   }
 }
 
-// This only applies to requests of a specific form:
-// 1. name/.*
-// 2. @scope/name/.*
+/**
+ * This only applies to requests of a specific form:
+ * 1. `name/.*`
+ * 2. `@scope/name/.*`
+ */
 const EXPORTS_PATTERN = /^((?:@[^/\\%]+\/)?[^./\\%][^/\\%]*)(\/.*)?$/;
+
+/**
+ * Resolves the exports for a given module path and request.
+ * @param {string} nmPath The path to the module.
+ * @param {string} request The request for the module.
+ */
 function resolveExports(nmPath, request) {
   // The implementation's behavior is meant to mirror resolution in ESM.
   const { 1: name, 2: expansion = '' } =
@@ -561,9 +655,10 @@ function resolveExports(nmPath, request) {
 }
 
 /**
- * @param {string} request a relative or absolute file path
- * @param {Array<string>} paths file system directories to search as file paths
- * @param {boolean} isMain if the request is the main app entry point
+ * Get the absolute path to a module.
+ * @param {string} request Relative or absolute file path
+ * @param {Array<string>} paths Folders to search as file paths
+ * @param {boolean} isMain Whether the request is the main app entry point
  * @returns {string | false}
  */
 Module._findPath = function(request, paths, isMain) {
@@ -689,11 +784,14 @@ Module._findPath = function(request, paths, isMain) {
   return false;
 };
 
-// 'node_modules' character codes reversed
+/** `node_modules` character codes reversed */
 const nmChars = [ 115, 101, 108, 117, 100, 111, 109, 95, 101, 100, 111, 110 ];
 const nmLen = nmChars.length;
 if (isWindows) {
-  // 'from' is the __dirname of the module.
+  /**
+   * Get the paths to the `node_modules` folder for a given path.
+   * @param {string} from `__dirname` of the module
+   */
   Module._nodeModulePaths = function(from) {
     // Guarantee that 'from' is absolute.
     from = path.resolve(from);
@@ -710,6 +808,7 @@ if (isWindows) {
       return [from + 'node_modules'];
     }
 
+    /** @type {string[]} */
     const paths = [];
     for (let i = from.length - 1, p = 0, last = from.length; i >= 0; --i) {
       const code = StringPrototypeCharCodeAt(from, i);
@@ -741,7 +840,10 @@ if (isWindows) {
     return paths;
   };
 } else { // posix
-  // 'from' is the __dirname of the module.
+  /**
+   * Get the paths to the `node_modules` folder for a given path.
+   * @param {string} from `__dirname` of the module
+   */
   Module._nodeModulePaths = function(from) {
     // Guarantee that 'from' is absolute.
     from = path.resolve(from);
@@ -754,6 +856,7 @@ if (isWindows) {
     // note: this approach *only* works when the path is guaranteed
     // to be absolute.  Doing a fully-edge-case-correct path.split
     // that works on both Windows and Posix is non-trivial.
+    /** @type {string[]} */
     const paths = [];
     for (let i = from.length - 1, p = 0, last = from.length; i >= 0; --i) {
       const code = StringPrototypeCharCodeAt(from, i);
@@ -782,6 +885,11 @@ if (isWindows) {
   };
 }
 
+/**
+ * Get the paths for module resolution.
+ * @param {string} request
+ * @param {Module} parent
+ */
 Module._resolveLookupPaths = function(request, parent) {
   if (BuiltinModule.normalizeRequirableId(request)) {
     debug('looking for %j in []', request);
@@ -795,6 +903,7 @@ Module._resolveLookupPaths = function(request, parent) {
       StringPrototypeCharAt(request, 1) !== '/' &&
       (!isWindows || StringPrototypeCharAt(request, 1) !== '\\'))) {
 
+    /** @type {string[]} */
     let paths;
     if (parent?.paths?.length) {
       paths = ArrayPrototypeSlice(modulePaths);
@@ -824,6 +933,10 @@ Module._resolveLookupPaths = function(request, parent) {
   return parentDir;
 };
 
+/**
+ * Emits a warning when a non-existent property of module exports is accessed inside a circular dependency.
+ * @param {string} prop The name of the non-existent property.
+ */
 function emitCircularRequireWarning(prop) {
   process.emitWarning(
     `Accessing non-existent property '${String(prop)}' of module exports ` +
@@ -854,6 +967,12 @@ const CircularRequirePrototypeWarningProxy = new Proxy({}, {
   },
 });
 
+/**
+ * Returns the exports object for a module that has a circular `require`.
+ * If the exports object is a plain object, it is wrapped in a proxy that warns
+ * about circular dependencies.
+ * @param {Module} module The module instance
+ */
 function getExportsForCircularRequire(module) {
   if (module.exports &&
       !isProxy(module.exports) &&
@@ -871,13 +990,17 @@ function getExportsForCircularRequire(module) {
   return module.exports;
 }
 
-// Check the cache for the requested file.
-// 1. If a module already exists in the cache: return its exports object.
-// 2. If the module is native: call
-//    `BuiltinModule.prototype.compileForPublicLoader()` and return the exports.
-// 3. Otherwise, create a new module for the file and save it to the cache.
-//    Then have it load  the file contents before returning its exports
-//    object.
+/**
+ * Load a module from cache if it exists, otherwise create a new module instance.
+ * 1. If a module already exists in the cache: return its exports object.
+ * 2. If the module is native: call
+ *    `BuiltinModule.prototype.compileForPublicLoader()` and return the exports.
+ * 3. Otherwise, create a new module for the file and save it to the cache.
+ *    Then have it load the file contents before returning its exports object.
+ * @param {string} request Specifier of module to load via `require`
+ * @param {string} parent Absolute path of the module importing the child
+ * @param {boolean} isMain Whether the module is the main entry point
+ */
 Module._load = function(request, parent, isMain) {
   let relResolveCacheIdentifier;
   if (parent) {
@@ -977,6 +1100,15 @@ Module._load = function(request, parent, isMain) {
   return module.exports;
 };
 
+/**
+ * Given a `require` string and its context, get its absolute file path.
+ * @param {string} request The specifier to resolve
+ * @param {Module} parent The module containing the `require` call
+ * @param {boolean} isMain Whether the module is the main entry point
+ * @param {ResolveFilenameOptions} options Options object
+ * @typedef {object} ResolveFilenameOptions
+ * @property {string[]} paths Paths to search for modules in
+ */
 Module._resolveFilename = function(request, parent, isMain, options) {
   if (BuiltinModule.normalizeRequirableId(request)) {
     return request;
@@ -1069,6 +1201,14 @@ Module._resolveFilename = function(request, parent, isMain, options) {
   throw err;
 };
 
+/**
+ * Finishes resolving an ES module specifier into an absolute file path.
+ * @param {string} resolved The resolved module specifier
+ * @param {string} parentPath The path of the parent module
+ * @param {string} pkgPath The path of the package.json file
+ * @throws {ERR_INVALID_MODULE_SPECIFIER} If the resolved module specifier contains encoded `/` or `\\` characters
+ * @throws {Error} If the module cannot be found
+ */
 function finalizeEsmResolution(resolved, parentPath, pkgPath) {
   const { encodedSepRegEx } = require('internal/modules/esm/resolve');
   if (RegExpPrototypeExec(encodedSepRegEx, resolved) !== null) {
@@ -1085,6 +1225,11 @@ function finalizeEsmResolution(resolved, parentPath, pkgPath) {
   throw err;
 }
 
+/**
+ * Creates an error object for when a requested ES module cannot be found.
+ * @param {string} request The name of the requested module
+ * @param {string} [path] The path to the requested module
+ */
 function createEsmNotFoundErr(request, path) {
   // eslint-disable-next-line no-restricted-syntax
   const err = new Error(`Cannot find module '${request}'`);
@@ -1096,7 +1241,10 @@ function createEsmNotFoundErr(request, path) {
   return err;
 }
 
-// Given a file name, pass it to the proper extension handler.
+/**
+ * Given a file name, pass it to the proper extension handler.
+ * @param {string} filename The `require` specifier
+ */
 Module.prototype.load = function(filename) {
   debug('load %j for module %j', filename, this.id);
 
@@ -1124,9 +1272,12 @@ Module.prototype.load = function(filename) {
   }
 };
 
-// Loads a module at the given file path. Returns that module's
-// `exports` property.
-// Note: when using the experimental policy mechanism this function is overridden
+/**
+ * Loads a module at the given file path. Returns that module's `exports` property.
+ * Note: when using the experimental policy mechanism this function is overridden.
+ * @param {string} id
+ * @throws {ERR_INVALID_ARG_TYPE} When `id` is not a string
+ */
 Module.prototype.require = function(id) {
   validateString(id, 'id');
   if (id === '') {
@@ -1141,11 +1292,23 @@ Module.prototype.require = function(id) {
   }
 };
 
-// Resolved path to process.argv[1] will be lazily placed here
-// (needed for setting breakpoint when called with --inspect-brk)
+/**
+ * Resolved path to `process.argv[1]` will be lazily placed here
+ * (needed for setting breakpoint when called with `--inspect-brk`).
+ * @type {string | undefined}
+ */
 let resolvedArgv;
 let hasPausedEntry = false;
+/** @type {import('vm').Script} */
 let Script;
+
+/**
+ * Wraps the given content in a script and runs it in a new context.
+ * @param {string} filename The name of the file being loaded
+ * @param {string} content The content of the file being loaded
+ * @param {Module} cjsModuleInstance The CommonJS loader instance
+ * @param {object} codeCache The SEA code cache
+ */
 function wrapSafe(filename, content, cjsModuleInstance, codeCache) {
   if (patched) {
     const wrapper = Module.wrap(content);
@@ -1211,10 +1374,12 @@ function wrapSafe(filename, content, cjsModuleInstance, codeCache) {
   }
 }
 
-// Run the file contents in the correct scope or sandbox. Expose
-// the correct helper variables (require, module, exports) to
-// the file.
-// Returns exception, if any.
+/**
+ * Run the file contents in the correct scope or sandbox. Expose the correct helper variables (`require`, `module`,
+ * `exports`) to the file. Returns exception, if any.
+ * @param {string} content The source code of the module
+ * @param {string} filename The file path of the module
+ */
 Module.prototype._compile = function(content, filename) {
   let moduleURL;
   let redirects;
@@ -1269,7 +1434,11 @@ Module.prototype._compile = function(content, filename) {
   return result;
 };
 
-// Native extension for .js
+/**
+ * Native handler for `.js` files.
+ * @param {Module} module The module to compile
+ * @param {string} filename The file path of the module
+ */
 Module._extensions['.js'] = function(module, filename) {
   // If already analyzed the source, then it will be cached.
   const cached = cjsParseCache.get(module);
@@ -1318,8 +1487,11 @@ Module._extensions['.js'] = function(module, filename) {
   module._compile(content, filename);
 };
 
-
-// Native extension for .json
+/**
+ * Native handler for `.json` files.
+ * @param {Module} module The module to compile
+ * @param {string} filename The file path of the module
+ */
 Module._extensions['.json'] = function(module, filename) {
   const content = fs.readFileSync(filename, 'utf8');
 
@@ -1337,8 +1509,11 @@ Module._extensions['.json'] = function(module, filename) {
   }
 };
 
-
-// Native extension for .node
+/**
+ * Native handler for `.node` files.
+ * @param {Module} module The module to compile
+ * @param {string} filename The file path of the module
+ */
 Module._extensions['.node'] = function(module, filename) {
   const manifest = policy()?.manifest;
   if (manifest) {
@@ -1350,6 +1525,10 @@ Module._extensions['.node'] = function(module, filename) {
   return process.dlopen(module, path.toNamespacedPath(filename));
 };
 
+/**
+ * Creates a `require` function that can be used to load modules from the specified path.
+ * @param {string} filename The path to the module
+ */
 function createRequireFromPath(filename) {
   // Allow a directory to be passed as the filename
   const trailingSlash =
@@ -1370,6 +1549,12 @@ function createRequireFromPath(filename) {
 const createRequireError = 'must be a file URL object, file URL string, or ' +
   'absolute path string';
 
+/**
+ * Creates a new `require` function that can be used to load modules.
+ * @param {string | URL} filename The path or URL to the module context for this `require`
+ * @throws {ERR_INVALID_ARG_VALUE} If `filename` is not a string or URL, or if it is a relative path that cannot be
+ * resolved to an absolute path.
+ */
 function createRequire(filename) {
   let filepath;
 
@@ -1391,6 +1576,9 @@ function createRequire(filename) {
 
 Module.createRequire = createRequire;
 
+/**
+ * Define the paths to use for resolving a module.
+ */
 Module._initPaths = function() {
   const homeDir = isWindows ? process.env.USERPROFILE : safeGetenv('HOME');
   const nodePath = isWindows ? process.env.NODE_PATH : safeGetenv('NODE_PATH');
@@ -1421,6 +1609,10 @@ Module._initPaths = function() {
   Module.globalPaths = ArrayPrototypeSlice(modulePaths);
 };
 
+/**
+ * Handle modules loaded via `--require`.
+ * @param {string[]} requests The values of `--require`
+ */
 Module._preloadModules = function(requests) {
   if (!ArrayIsArray(requests)) { return; }
 
@@ -1444,6 +1636,10 @@ Module._preloadModules = function(requests) {
   isPreloading = false;
 };
 
+/**
+ * If the user has overridden an export from a builtin module, this function can ensure that the override is used in
+ * both CommonJS and ES module contexts.
+ */
 Module.syncBuiltinESMExports = function syncBuiltinESMExports() {
   for (const mod of BuiltinModule.map.values()) {
     if (BuiltinModule.canBeRequiredWithoutScheme(mod.id)) {
diff --git a/lib/internal/modules/esm/create_dynamic_module.js b/lib/internal/modules/esm/create_dynamic_module.js
index 7df2290d4a8e6d..2eac81a82211ee 100644
--- a/lib/internal/modules/esm/create_dynamic_module.js
+++ b/lib/internal/modules/esm/create_dynamic_module.js
@@ -11,12 +11,21 @@ let debug = require('internal/util/debuglog').debuglog('esm', (fn) => {
   debug = fn;
 });
 
+/**
+ * Creates an import statement for a given module path and index.
+ * @param {string} impt - The module path to import.
+ * @param {number} index - The index of the import statement.
+ */
 function createImport(impt, index) {
   const imptPath = JSONStringify(impt);
   return `import * as $import_${index} from ${imptPath};
 import.meta.imports[${imptPath}] = $import_${index};`;
 }
 
+/**
+ * Creates an export for a given module.
+ * @param {string} expt - The name of the export.
+ */
 function createExport(expt) {
   const name = `${expt}`;
   return `let $${name};
@@ -27,6 +36,17 @@ import.meta.exports.${name} = {
 };`;
 }
 
+/**
+ * Creates a dynamic module with the given imports, exports, URL, and evaluate function.
+ * @param {string[]} imports - An array of imports.
+ * @param {string[]} exports - An array of exports.
+ * @param {string} [url=''] - The URL of the module.
+ * @param {(reflect: DynamicModuleReflect) => void} evaluate - The function to evaluate the module.
+ * @typedef {object} DynamicModuleReflect
+ * @property {string[]} imports - The imports of the module.
+ * @property {string[]} exports - The exports of the module.
+ * @property {(cb: (reflect: DynamicModuleReflect) => void) => void} onReady - Callback to evaluate the module.
+ */
 const createDynamicModule = (imports, exports, url = '', evaluate) => {
   debug('creating ESM facade for %s with exports: %j', url, exports);
   const source = `
@@ -38,6 +58,7 @@ import.meta.done();
   const m = new ModuleWrap(`${url}`, undefined, source, 0, 0);
 
   const readyfns = new SafeSet();
+  /** @type {DynamicModuleReflect} */
   const reflect = {
     exports: { __proto__: null },
     onReady: (cb) => { readyfns.add(cb); },
diff --git a/lib/internal/modules/esm/fetch_module.js b/lib/internal/modules/esm/fetch_module.js
index ca5c9c83c316de..21b7456899604f 100644
--- a/lib/internal/modules/esm/fetch_module.js
+++ b/lib/internal/modules/esm/fetch_module.js
@@ -44,37 +44,56 @@ const cacheForGET = new SafeMap();
 // [2] Creating a new agent instead of using the gloabl agent improves
 // performance and precludes the agent becoming tainted.
 
+/** @type {import('https').Agent} The Cached HTTP Agent for **secure** HTTP requests. */
 let HTTPSAgent;
-function HTTPSGet(url, opts) {
+/**
+ * Make a HTTPs GET request (handling agent setup if needed, caching the agent to avoid
+ * redudant instantiations).
+ * @param {Parameters<import('https').get>[0]} input - The URI to fetch.
+ * @param {Parameters<import('https').get>[1]} options - See https.get() options.
+ */
+function HTTPSGet(input, options) {
   const https = require('https'); // [1]
   HTTPSAgent ??= new https.Agent({ // [2]
     keepAlive: true,
   });
-  return https.get(url, {
+  return https.get(input, {
     agent: HTTPSAgent,
-    ...opts,
+    ...options,
   });
 }
 
+/** @type {import('https').Agent} The Cached HTTP Agent for **insecure** HTTP requests. */
 let HTTPAgent;
-function HTTPGet(url, opts) {
+/**
+ * Make a HTTP GET request (handling agent setup if needed, caching the agent to avoid
+ * redudant instantiations).
+ * @param {Parameters<import('http').get>[0]} input - The URI to fetch.
+ * @param {Parameters<import('http').get>[1]} options - See http.get() options.
+ */
+function HTTPGet(input, options) {
   const http = require('http'); // [1]
   HTTPAgent ??= new http.Agent({ // [2]
     keepAlive: true,
   });
-  return http.get(url, {
+  return http.get(input, {
     agent: HTTPAgent,
-    ...opts,
+    ...options,
   });
 }
 
-function dnsLookup(name, opts) {
+/** @type {import('../../dns/promises.js').lookup} */
+function dnsLookup(hostname, options) {
   // eslint-disable-next-line no-func-assign
   dnsLookup = require('dns/promises').lookup;
-  return dnsLookup(name, opts);
+  return dnsLookup(hostname, options);
 }
 
 let zlib;
+/**
+ * Create a decompressor for the Brotli format.
+ * @returns {import('zlib').BrotliDecompress}
+ */
 function createBrotliDecompress() {
   zlib ??= require('zlib'); // [1]
   // eslint-disable-next-line no-func-assign
@@ -82,6 +101,10 @@ function createBrotliDecompress() {
   return createBrotliDecompress();
 }
 
+/**
+ * Create an unzip handler.
+ * @returns {import('zlib').Unzip}
+ */
 function createUnzip() {
   zlib ??= require('zlib'); // [1]
   // eslint-disable-next-line no-func-assign
diff --git a/lib/internal/modules/esm/handle_process_exit.js b/lib/internal/modules/esm/handle_process_exit.js
index 9d6b609ef1cfc3..4689ef6bb204c0 100644
--- a/lib/internal/modules/esm/handle_process_exit.js
+++ b/lib/internal/modules/esm/handle_process_exit.js
@@ -2,9 +2,11 @@
 
 const { exitCodes: { kUnfinishedTopLevelAwait } } = internalBinding('errors');
 
-// Handle a Promise from running code that potentially does Top-Level Await.
-// In that case, it makes sense to set the exit code to a specific non-zero
-// value if the main code never finishes running.
+/**
+ * Handle a Promise from running code that potentially does Top-Level Await.
+ * In that case, it makes sense to set the exit code to a specific non-zero value
+ * if the main code never finishes running.
+ */
 function handleProcessExit() {
   process.exitCode ??= kUnfinishedTopLevelAwait;
 }
diff --git a/lib/internal/modules/esm/loader.js b/lib/internal/modules/esm/loader.js
index 7712e6359882f1..8cbd255a5550ba 100644
--- a/lib/internal/modules/esm/loader.js
+++ b/lib/internal/modules/esm/loader.js
@@ -21,16 +21,28 @@ const {
 } = require('internal/modules/esm/utils');
 let defaultResolve, defaultLoad, defaultLoadSync, importMetaInitializer;
 
+/**
+ * Lazy loads the module_map module and returns a new instance of ResolveCache.
+ * @returns {import('./module_map.js').ResolveCache')}
+ */
 function newResolveCache() {
   const { ResolveCache } = require('internal/modules/esm/module_map');
   return new ResolveCache();
 }
 
+/**
+ * Generate a load cache (to store the final result of a load-chain for a particular module).
+ * @returns {import('./module_map.js').LoadCache')}
+ */
 function newLoadCache() {
   const { LoadCache } = require('internal/modules/esm/module_map');
   return new LoadCache();
 }
 
+/**
+ * Lazy-load translators to avoid potentially unnecessary work at startup (ex if ESM is not used).
+ * @returns {import('./translators.js').Translators}
+ */
 function getTranslators() {
   const { translators } = require('internal/modules/esm/translators');
   return translators;
diff --git a/lib/internal/modules/esm/package_config.js b/lib/internal/modules/esm/package_config.js
index 4ca701d4810f74..5da47764c9de2c 100644
--- a/lib/internal/modules/esm/package_config.js
+++ b/lib/internal/modules/esm/package_config.js
@@ -7,8 +7,23 @@ const { URL, fileURLToPath } = require('internal/url');
 const packageJsonReader = require('internal/modules/package_json_reader');
 
 /**
- * @param {URL | string} resolved
- * @returns {PackageConfig}
+ * @typedef {object} PackageConfig
+ * @property {string} pjsonPath - The path to the package.json file.
+ * @property {boolean} exists - Whether the package.json file exists.
+ * @property {'none' | 'commonjs' | 'module'} type - The type of the package.
+ * @property {string} [name] - The name of the package.
+ * @property {string} [main] - The main entry point of the package.
+ * @property {PackageTarget} [exports] - The exports configuration of the package.
+ * @property {Record<string, string | Record<string, string>>} [imports] - The imports configuration of the package.
+ */
+/**
+ * @typedef {string | string[] | Record<string, string | Record<string, string>>} PackageTarget
+ */
+
+/**
+ * Returns the package configuration for the given resolved URL.
+ * @param {URL | string} resolved - The resolved URL.
+ * @returns {PackageConfig} - The package configuration.
  */
 function getPackageScopeConfig(resolved) {
   let packageJSONUrl = new URL('./package.json', resolved);
diff --git a/lib/internal/modules/esm/resolve.js b/lib/internal/modules/esm/resolve.js
index 8f3b289126bb82..84276919640118 100644
--- a/lib/internal/modules/esm/resolve.js
+++ b/lib/internal/modules/esm/resolve.js
@@ -66,6 +66,13 @@ const { internalModuleStat } = internalBinding('fs');
 
 const emittedPackageWarnings = new SafeSet();
 
+/**
+ * Emits a deprecation warning for the use of a deprecated trailing slash pattern mapping in the "exports" field
+ * module resolution of a package.
+ * @param {string} match - The deprecated trailing slash pattern mapping.
+ * @param {string} pjsonUrl - The URL of the package.json file.
+ * @param {string} base - The URL of the module that imported the package.
+ */
 function emitTrailingSlashPatternDeprecation(match, pjsonUrl, base) {
   const pjsonPath = fileURLToPath(pjsonUrl);
   if (emittedPackageWarnings.has(pjsonPath + '|' + match)) { return; }
@@ -82,6 +89,16 @@ function emitTrailingSlashPatternDeprecation(match, pjsonUrl, base) {
 
 const doubleSlashRegEx = /[/\\][/\\]/;
 
+/**
+ * Emits a deprecation warning for invalid segment in module resolution.
+ * @param {string} target - The target module.
+ * @param {string} request - The requested module.
+ * @param {string} match - The matched module.
+ * @param {string} pjsonUrl - The package.json URL.
+ * @param {boolean} internal - Whether the module is in the "imports" or "exports" field.
+ * @param {string} base - The base URL.
+ * @param {boolean} isTarget - Whether the target is a module.
+ */
 function emitInvalidSegmentDeprecation(target, request, match, pjsonUrl, internal, base, isTarget) {
   const pjsonPath = fileURLToPath(pjsonUrl);
   const double = RegExpPrototypeExec(doubleSlashRegEx, isTarget ? target : request) !== null;
@@ -97,11 +114,12 @@ function emitInvalidSegmentDeprecation(target, request, match, pjsonUrl, interna
 }
 
 /**
- * @param {URL} url
- * @param {URL} packageJSONUrl
- * @param {string | URL | undefined} base
- * @param {string} [main]
- * @returns {void}
+ * Emits a deprecation warning if the given URL is a module and
+ * the package.json file does not define a "main" or "exports" field.
+ * @param {URL} url - The URL of the module being resolved.
+ * @param {URL} packageJSONUrl - The URL of the package.json file for the module.
+ * @param {string | URL} [base] - The base URL for the module being resolved.
+ * @param {string} [main] - The "main" field from the package.json file.
  */
 function emitLegacyIndexDeprecation(url, packageJSONUrl, base, main) {
   const format = defaultGetFormatWithoutErrors(url);
@@ -195,10 +213,15 @@ function legacyMainResolve(packageJSONUrl, packageConfig, base) {
 
 const encodedSepRegEx = /%2F|%5C/i;
 /**
- * @param {URL} resolved
- * @param {string | URL | undefined} base
- * @param {boolean} preserveSymlinks
- * @returns {URL | undefined}
+ * Finalizes the resolution of a module specifier by checking if the resolved pathname contains encoded "/" or "\\"
+ * characters, checking if the resolved pathname is a directory or file, and resolving any symlinks if necessary.
+ * @param {URL} resolved - The resolved URL object.
+ * @param {string | URL | undefined} base - The base URL object.
+ * @param {boolean} preserveSymlinks - Whether to preserve symlinks or not.
+ * @returns {URL} - The finalized URL object.
+ * @throws {ERR_INVALID_MODULE_SPECIFIER} - If the resolved pathname contains encoded "/" or "\\" characters.
+ * @throws {ERR_UNSUPPORTED_DIR_IMPORT} - If the resolved pathname is a directory.
+ * @throws {ERR_MODULE_NOT_FOUND} - If the resolved pathname is not a file.
  */
 function finalizeResolution(resolved, base, preserveSymlinks) {
   if (RegExpPrototypeExec(encodedSepRegEx, resolved.pathname) !== null) {
@@ -239,9 +262,11 @@ function finalizeResolution(resolved, base, preserveSymlinks) {
 }
 
 /**
- * @param {string} specifier
- * @param {URL} packageJSONUrl
- * @param {string | URL | undefined} base
+ * Returns an error object indicating that the specified import is not defined.
+ * @param {string} specifier - The import specifier that is not defined.
+ * @param {URL} packageJSONUrl - The URL of the package.json file, or null if not available.
+ * @param {string | URL | undefined} base - The base URL to use for resolving relative URLs.
+ * @returns {ERR_PACKAGE_IMPORT_NOT_DEFINED} - The error object.
  */
 function importNotDefined(specifier, packageJSONUrl, base) {
   return new ERR_PACKAGE_IMPORT_NOT_DEFINED(
@@ -250,9 +275,11 @@ function importNotDefined(specifier, packageJSONUrl, base) {
 }
 
 /**
- * @param {string} subpath
- * @param {URL} packageJSONUrl
- * @param {string | URL | undefined} base
+ * Returns an error object indicating that the specified subpath was not exported by the package.
+ * @param {string} subpath - The subpath that was not exported.
+ * @param {URL} packageJSONUrl - The URL of the package.json file.
+ * @param {string | URL | undefined} [base] - The base URL to use for resolving the subpath.
+ * @returns {ERR_PACKAGE_PATH_NOT_EXPORTED} - The error object.
  */
 function exportsNotFound(subpath, packageJSONUrl, base) {
   return new ERR_PACKAGE_PATH_NOT_EXPORTED(
@@ -261,12 +288,13 @@ function exportsNotFound(subpath, packageJSONUrl, base) {
 }
 
 /**
- *
- * @param {string} request
- * @param {string} match
- * @param {URL} packageJSONUrl
- * @param {boolean} internal
- * @param {string | URL | undefined} base
+ * Throws an error indicating that the given request is not a valid subpath match for the specified pattern.
+ * @param {string} request - The request that failed to match the pattern.
+ * @param {string} match - The pattern that the request was compared against.
+ * @param {URL} packageJSONUrl - The URL of the package.json file being resolved.
+ * @param {boolean} internal - Whether the resolution is for an "imports" or "exports" field in package.json.
+ * @param {string | URL | undefined} base - The base URL for the resolution.
+ * @throws {ERR_INVALID_MODULE_SPECIFIER} When the request is not a valid match for the pattern.
  */
 function throwInvalidSubpath(request, match, packageJSONUrl, internal, base) {
   const reason = `request is not a valid match in pattern "${match}" for the "${
@@ -276,6 +304,15 @@ function throwInvalidSubpath(request, match, packageJSONUrl, internal, base) {
                                          base && fileURLToPath(base));
 }
 
+/**
+ * Creates an error object for an invalid package target.
+ * @param {string} subpath - The subpath.
+ * @param {import('internal/modules/esm/package_config.js').PackageTarget} target - The target.
+ * @param {URL} packageJSONUrl - The URL of the package.json file.
+ * @param {boolean} internal - Whether the package is internal.
+ * @param {string | URL | undefined} base - The base URL.
+ * @returns {ERR_INVALID_PACKAGE_TARGET} - The error object.
+ */
 function invalidPackageTarget(
   subpath, target, packageJSONUrl, internal, base) {
   if (typeof target === 'object' && target !== null) {
@@ -294,17 +331,19 @@ const invalidPackageNameRegEx = /^\.|%|\\/;
 const patternRegEx = /\*/g;
 
 /**
- *
- * @param {string} target
- * @param {*} subpath
- * @param {*} match
- * @param {*} packageJSONUrl
- * @param {*} base
- * @param {*} pattern
- * @param {*} internal
- * @param {*} isPathMap
- * @param {*} conditions
- * @returns {URL}
+ * Resolves the package target string to a URL object.
+ * @param {string} target - The target string to resolve.
+ * @param {string} subpath - The subpath to append to the resolved URL.
+ * @param {RegExpMatchArray} match - The matched string array from the import statement.
+ * @param {string} packageJSONUrl - The URL of the package.json file.
+ * @param {string} base - The base URL to resolve the target against.
+ * @param {RegExp} pattern - The pattern to replace in the target string.
+ * @param {boolean} internal - Whether the target is internal to the package.
+ * @param {boolean} isPathMap - Whether the target is a path map.
+ * @param {string[]} conditions - The import conditions.
+ * @returns {URL} - The resolved URL object.
+ * @throws {ERR_INVALID_PACKAGE_TARGET} - If the target is invalid.
+ * @throws {ERR_INVALID_SUBPATH} - If the subpath is invalid.
  */
 function resolvePackageTargetString(
   target,
@@ -387,8 +426,9 @@ function resolvePackageTargetString(
 }
 
 /**
- * @param {string} key
- * @returns {boolean}
+ * Checks if the given key is a valid array index.
+ * @param {string} key - The key to check.
+ * @returns {boolean} - Returns `true` if the key is a valid array index, else `false`.
  */
 function isArrayIndex(key) {
   const keyNum = +key;
@@ -397,17 +437,17 @@ function isArrayIndex(key) {
 }
 
 /**
- *
- * @param {*} packageJSONUrl
- * @param {string|[string]} target
- * @param {*} subpath
- * @param {*} packageSubpath
- * @param {*} base
- * @param {*} pattern
- * @param {*} internal
- * @param {*} isPathMap
- * @param {*} conditions
- * @returns {URL|null}
+ * Resolves the target of a package based on the provided parameters.
+ * @param {string} packageJSONUrl - The URL of the package.json file.
+ * @param {import('internal/modules/esm/package_config.js').PackageTarget} target - The target to resolve.
+ * @param {string} subpath - The subpath to resolve.
+ * @param {string} packageSubpath - The subpath of the package to resolve.
+ * @param {string} base - The base path to resolve.
+ * @param {RegExp} pattern - The pattern to match.
+ * @param {boolean} internal - Whether the package is internal.
+ * @param {boolean} isPathMap - Whether the package is a path map.
+ * @param {Set<string>} conditions - The conditions to match.
+ * @returns {URL | null | undefined} - The resolved target, or null if not found, or undefined if not resolvable.
  */
 function resolvePackageTarget(packageJSONUrl, target, subpath, packageSubpath,
                               base, pattern, internal, isPathMap, conditions) {
@@ -478,11 +518,10 @@ function resolvePackageTarget(packageJSONUrl, target, subpath, packageSubpath,
 }
 
 /**
- *
- * @param {import('internal/modules/esm/package_config.js').Exports} exports
- * @param {URL} packageJSONUrl
- * @param {string | URL | undefined} base
- * @returns {boolean}
+ * Is the given exports object using the shorthand syntax?
+ * @param {import('internal/modules/esm/package_config.js').PackageConfig['exports']} exports
+ * @param {URL} packageJSONUrl The URL of the package.json file.
+ * @param {string | URL | undefined} base The base URL.
  */
 function isConditionalExportsMainSugar(exports, packageJSONUrl, base) {
   if (typeof exports === 'string' || ArrayIsArray(exports)) { return true; }
@@ -508,12 +547,13 @@ function isConditionalExportsMainSugar(exports, packageJSONUrl, base) {
 }
 
 /**
- * @param {URL} packageJSONUrl
- * @param {string} packageSubpath
- * @param {PackageConfig} packageConfig
- * @param {string | URL | undefined} base
- * @param {Set<string>} conditions
- * @returns {URL}
+ * Resolves the exports of a package.
+ * @param {URL} packageJSONUrl - The URL of the package.json file.
+ * @param {string} packageSubpath - The subpath of the package to resolve.
+ * @param {import('internal/modules/esm/package_config.js').PackageConfig} packageConfig - The package metadata.
+ * @param {string | URL | undefined} base - The base path to resolve from.
+ * @param {Set<string>} conditions - An array of conditions to match.
+ * @returns {URL} - The resolved package target.
  */
 function packageExportsResolve(
   packageJSONUrl, packageSubpath, packageConfig, base, conditions) {
@@ -592,6 +632,13 @@ function packageExportsResolve(
   throw exportsNotFound(packageSubpath, packageJSONUrl, base);
 }
 
+/**
+ * Compares two strings that may contain a wildcard character ('*') and returns a value indicating their order.
+ * @param {string} a - The first string to compare.
+ * @param {string} b - The second string to compare.
+ * @returns {number} - A negative number if `a` should come before `b`, a positive number if `a` should come after `b`,
+ * or 0 if they are equal.
+ */
 function patternKeyCompare(a, b) {
   const aPatternIndex = StringPrototypeIndexOf(a, '*');
   const bPatternIndex = StringPrototypeIndexOf(b, '*');
@@ -607,10 +654,13 @@ function patternKeyCompare(a, b) {
 }
 
 /**
- * @param {string} name
- * @param {string | URL | undefined} base
- * @param {Set<string>} conditions
- * @returns {URL}
+ * Resolves the given import name for a package.
+ * @param {string} name - The name of the import to resolve.
+ * @param {string | URL | undefined} base - The base URL to resolve the import from.
+ * @param {Set<string>} conditions - An object containing the import conditions.
+ * @throws {ERR_INVALID_MODULE_SPECIFIER} If the import name is not valid.
+ * @throws {ERR_PACKAGE_IMPORT_NOT_DEFINED} If the import name cannot be resolved.
+ * @returns {URL} The resolved import URL.
  */
 function packageImportsResolve(name, base, conditions) {
   if (name === '#' || StringPrototypeStartsWith(name, '#/') ||
@@ -673,8 +723,8 @@ function packageImportsResolve(name, base, conditions) {
 }
 
 /**
- * @param {URL} url
- * @returns {import('internal/modules/esm/package_config.js').PackageType}
+ * Returns the package type for a given URL.
+ * @param {URL} url - The URL to get the package type for.
  */
 function getPackageType(url) {
   const packageConfig = getPackageScopeConfig(url);
@@ -682,9 +732,9 @@ function getPackageType(url) {
 }
 
 /**
- * @param {string} specifier
- * @param {string | URL | undefined} base
- * @returns {{ packageName: string, packageSubpath: string, isScoped: boolean }}
+ * Parse a package name from a specifier.
+ * @param {string} specifier - The import specifier.
+ * @param {string | URL | undefined} base - The parent URL.
  */
 function parsePackageName(specifier, base) {
   let separatorIndex = StringPrototypeIndexOf(specifier, '/');
@@ -721,10 +771,11 @@ function parsePackageName(specifier, base) {
 }
 
 /**
- * @param {string} specifier
- * @param {string | URL | undefined} base
- * @param {Set<string>} conditions
- * @returns {resolved: URL, format? : string}
+ * Resolves a package specifier to a URL.
+ * @param {string} specifier - The package specifier to resolve.
+ * @param {string | URL | undefined} base - The base URL to use for resolution.
+ * @param {Set<string>} conditions - An object containing the conditions for resolution.
+ * @returns {URL} - The resolved URL.
  */
 function packageResolve(specifier, base, conditions) {
   if (BuiltinModule.canBeRequiredWithoutScheme(specifier)) {
@@ -785,13 +836,17 @@ function packageResolve(specifier, base, conditions) {
 }
 
 /**
- * @param {string} specifier
- * @returns {boolean}
+ * Checks if a specifier is a bare specifier.
+ * @param {string} specifier - The specifier to check.
  */
 function isBareSpecifier(specifier) {
   return specifier[0] && specifier[0] !== '/' && specifier[0] !== '.';
 }
 
+/**
+ * Determines whether a specifier is a relative path.
+ * @param {string} specifier - The specifier to check.
+ */
 function isRelativeSpecifier(specifier) {
   if (specifier[0] === '.') {
     if (specifier.length === 1 || specifier[1] === '/') { return true; }
@@ -802,6 +857,10 @@ function isRelativeSpecifier(specifier) {
   return false;
 }
 
+/**
+ * Determines whether a specifier should be treated as a relative or absolute path.
+ * @param {string} specifier - The specifier to check.
+ */
 function shouldBeTreatedAsRelativeOrAbsolutePath(specifier) {
   if (specifier === '') { return false; }
   if (specifier[0] === '/') { return true; }
@@ -809,11 +868,11 @@ function shouldBeTreatedAsRelativeOrAbsolutePath(specifier) {
 }
 
 /**
- * @param {string} specifier
- * @param {string | URL | undefined} base
- * @param {Set<string>} conditions
- * @param {boolean} preserveSymlinks
- * @returns {url: URL, format?: string}
+ * Resolves a module specifier to a URL.
+ * @param {string} specifier - The module specifier to resolve.
+ * @param {string | URL | undefined} base - The base URL to resolve against.
+ * @param {Set<string>} conditions - An object containing environment conditions.
+ * @param {boolean} preserveSymlinks - Whether to preserve symlinks in the resolved URL.
  */
 function moduleResolve(specifier, base, conditions, preserveSymlinks) {
   const isRemote = base.protocol === 'http:' ||
@@ -841,10 +900,9 @@ function moduleResolve(specifier, base, conditions, preserveSymlinks) {
 }
 
 /**
- * Try to resolve an import as a CommonJS module
- * @param {string} specifier
- * @param {string} parentURL
- * @returns {boolean|string}
+ * Try to resolve an import as a CommonJS module.
+ * @param {string} specifier - The specifier to resolve.
+ * @param {string} parentURL - The base URL.
  */
 function resolveAsCommonJS(specifier, parentURL) {
   try {
@@ -886,7 +944,14 @@ function resolveAsCommonJS(specifier, parentURL) {
   }
 }
 
-// TODO(@JakobJingleheimer): de-dupe `specifier` & `parsed`
+/**
+ * Throw an error if an import is not allowed.
+ * TODO(@JakobJingleheimer): de-dupe `specifier` & `parsed`
+ * @param {string} specifier - The import specifier.
+ * @param {URL} parsed - The parsed URL of the import specifier.
+ * @param {URL} parsedParentURL - The parsed URL of the parent module.
+ * @throws {ERR_NETWORK_IMPORT_DISALLOWED} - If the import is disallowed.
+ */
 function checkIfDisallowedImport(specifier, parsed, parsedParentURL) {
   if (parsedParentURL) {
     // Avoid accessing the `protocol` property due to the lazy getters.
@@ -932,6 +997,7 @@ function checkIfDisallowedImport(specifier, parsed, parsedParentURL) {
 
 /**
  * Validate user-input in `context` supplied by a custom loader.
+ * @param {string | URL | undefined} parentURL - The parent URL.
  */
 function throwIfInvalidParentURL(parentURL) {
   if (parentURL === undefined) {
@@ -942,7 +1008,15 @@ function throwIfInvalidParentURL(parentURL) {
   }
 }
 
-
+/**
+ * Resolves the given specifier using the provided context, which includes the parent URL and conditions.
+ * Throws an error if the parent URL is invalid or if the resolution is disallowed by the policy manifest.
+ * Otherwise, attempts to resolve the specifier and returns the resulting URL and format.
+ * @param {string} specifier - The specifier to resolve.
+ * @param {object} [context={}] - The context object containing the parent URL and conditions.
+ * @param {string} [context.parentURL] - The URL of the parent module.
+ * @param {string[]} [context.conditions] - The conditions for resolving the specifier.
+ */
 function defaultResolve(specifier, context = {}) {
   let { parentURL, conditions } = context;
   throwIfInvalidParentURL(parentURL);
diff --git a/lib/internal/modules/esm/translators.js b/lib/internal/modules/esm/translators.js
index 62d721552ef6af..bd67593f993e07 100644
--- a/lib/internal/modules/esm/translators.js
+++ b/lib/internal/modules/esm/translators.js
@@ -18,7 +18,11 @@ const {
   globalThis: { WebAssembly },
 } = primordials;
 
+/** @type {import('internal/util/types')} */
 let _TYPES = null;
+/**
+ * Lazily loads and returns the internal/util/types module.
+ */
 function lazyTypes() {
   if (_TYPES !== null) { return _TYPES; }
   return _TYPES = require('internal/util/types');
@@ -52,7 +56,13 @@ const asyncESM = require('internal/process/esm_loader');
 const { emitWarningSync } = require('internal/process/warning');
 const { internalCompileFunction } = require('internal/vm');
 
+/** @type {import('deps/cjs-module-lexer/lexer.js').parse} */
 let cjsParse;
+/**
+ * Initializes the CommonJS module lexer parser.
+ * If WebAssembly is available, it uses the optimized version from the dist folder.
+ * Otherwise, it falls back to the JavaScript version from the lexer folder.
+ */
 async function initCJSParse() {
   if (typeof WebAssembly === 'undefined') {
     cjsParse = require('internal/deps/cjs-module-lexer/lexer').parse;
@@ -73,6 +83,14 @@ exports.translators = translators;
 exports.enrichCJSError = enrichCJSError;
 
 let DECODER = null;
+/**
+ * Asserts that the given body is a buffer source (either a string, array buffer, or typed array).
+ * Throws an error if the body is not a buffer source.
+ * @param {string | ArrayBufferView | ArrayBuffer} body - The body to check.
+ * @param {boolean} allowString - Whether or not to allow a string as a valid buffer source.
+ * @param {string} hookName - The name of the hook being called.
+ * @throws {ERR_INVALID_RETURN_PROPERTY_VALUE} If the body is not a buffer source.
+ */
 function assertBufferSource(body, allowString, hookName) {
   if (allowString && typeof body === 'string') {
     return;
@@ -89,6 +107,11 @@ function assertBufferSource(body, allowString, hookName) {
   );
 }
 
+/**
+ * Converts a buffer or buffer-like object to a string.
+ * @param {string | ArrayBuffer | ArrayBufferView} body - The buffer or buffer-like object to convert to a string.
+ * @returns {string} The resulting string.
+ */
 function stringify(body) {
   if (typeof body === 'string') { return body; }
   assertBufferSource(body, false, 'transformSource');
@@ -97,6 +120,10 @@ function stringify(body) {
   return DECODER.decode(body);
 }
 
+/**
+ * Converts a URL to a file path if the URL protocol is 'file:'.
+ * @param {string} url - The URL to convert.
+ */
 function errPath(url) {
   const parsed = new URL(url);
   if (parsed.protocol === 'file:') {
@@ -105,6 +132,14 @@ function errPath(url) {
   return url;
 }
 
+/**
+ * Dynamically imports a module using the ESM loader.
+ * @param {string} specifier - The module specifier to import.
+ * @param {object} options - An object containing options for the import.
+ * @param {string} options.url - The URL of the module requesting the import.
+ * @param {Record<string, string>} [assertions] - An object containing assertions for the import.
+ * @returns {Promise<import('internal/modules/esm/loader.js').ModuleExports>} The imported module.
+ */
 async function importModuleDynamically(specifier, { url }, assertions) {
   return asyncESM.esmLoader.import(specifier, url, assertions);
 }
@@ -126,6 +161,7 @@ translators.set('module', async function moduleStrategy(url, source, isMain) {
 });
 
 /**
+ * Provide a more informative error for CommonJS imports.
  * @param {Error | any} err
  * @param {string} [content] Content of the file, if known.
  * @param {string} [filename] Useful only if `content` is unknown.
@@ -148,6 +184,10 @@ function enrichCJSError(err, content, filename) {
  * This translator creates its own version of the `require` function passed into CommonJS modules.
  * Any monkey patches applied to the CommonJS Loader will not affect this module.
  * Any `require` calls in this module will load all children in the same way.
+ * @param {import('internal/modules/cjs/loader').Module} module - The module to load.
+ * @param {string} source - The source code of the module.
+ * @param {string} url - The URL of the module.
+ * @param {string} filename - The filename of the module.
  */
 function loadCJSModule(module, source, url, filename) {
   let compiledWrapper;
@@ -212,6 +252,14 @@ function loadCJSModule(module, source, url, filename) {
 
 // TODO: can we use a weak map instead?
 const cjsCache = new SafeMap();
+/**
+ * Creates a ModuleWrap object for a CommonJS module.
+ * @param {string} url - The URL of the module.
+ * @param {string} source - The source code of the module.
+ * @param {boolean} isMain - Whether the module is the main module.
+ * @param {typeof loadCJSModule} [loadCJS=loadCJSModule] - The function to load the CommonJS module.
+ * @returns {ModuleWrap} The ModuleWrap object for the CommonJS module.
+ */
 function createCJSModuleWrap(url, source, isMain, loadCJS = loadCJSModule) {
   debug(`Translating CJSModule ${url}`);
 
@@ -299,6 +347,11 @@ translators.set('commonjs', async function commonjsStrategy(url, source,
 
 });
 
+/**
+ * Pre-parses a CommonJS module's exports and re-exports.
+ * @param {string} filename - The filename of the module.
+ * @param {string} [source] - The source code of the module.
+ */
 function cjsPreparseModuleExports(filename, source) {
   // TODO: Do we want to keep hitting the user mutable CJS loader here?
   let module = CJSModule._cache[filename];
diff --git a/lib/internal/modules/esm/utils.js b/lib/internal/modules/esm/utils.js
index 82d892a96f1936..b101bf6f69bac8 100644
--- a/lib/internal/modules/esm/utils.js
+++ b/lib/internal/modules/esm/utils.js
@@ -29,18 +29,28 @@ const {
 const assert = require('internal/assert');
 
 let defaultConditions;
+/**
+ * Returns the default conditions for ES module loading.
+ */
 function getDefaultConditions() {
   assert(defaultConditions !== undefined);
   return defaultConditions;
 }
 
+/** @type {Set<string>} */
 let defaultConditionsSet;
+/**
+ * Returns the default conditions for ES module loading, as a Set.
+ */
 function getDefaultConditionsSet() {
   assert(defaultConditionsSet !== undefined);
   return defaultConditionsSet;
 }
 
-// This function is called during pre-execution, before any user code is run.
+/**
+ * Initializes the default conditions for ESM module loading.
+ * This function is called during pre-execution, before any user code is run.
+ */
 function initializeDefaultConditions() {
   const userConditions = getOptionValue('--conditions');
   const noAddons = getOptionValue('--no-addons');
@@ -123,7 +133,11 @@ function registerModule(referrer, registry) {
   moduleRegistries.set(idSymbol, registry);
 }
 
-// The native callback
+/**
+ * Defines the `import.meta` object for a given module.
+ * @param {symbol} symbol - Reference to the module.
+ * @param {Record<string, string | Function>} meta - The import.meta object to initialize.
+ */
 function initializeImportMetaObject(symbol, meta) {
   if (moduleRegistries.has(symbol)) {
     const { initializeImportMeta, callbackReferrer } = moduleRegistries.get(symbol);
@@ -133,7 +147,14 @@ function initializeImportMetaObject(symbol, meta) {
   }
 }
 
-// The native callback
+/**
+ * Asynchronously imports a module dynamically using a callback function. The native callback.
+ * @param {symbol} symbol - Reference to the module.
+ * @param {string} specifier - The module specifier string.
+ * @param {Record<string, string>} assertions - The import assertions object.
+ * @returns {Promise<import('internal/modules/esm/loader.js').ModuleExports>} - The imported module object.
+ * @throws {ERR_VM_DYNAMIC_IMPORT_CALLBACK_MISSING} - If the callback function is missing.
+ */
 async function importModuleDynamicallyCallback(symbol, specifier, assertions) {
   if (moduleRegistries.has(symbol)) {
     const { importModuleDynamically, callbackReferrer } = moduleRegistries.get(symbol);
@@ -144,9 +165,13 @@ async function importModuleDynamicallyCallback(symbol, specifier, assertions) {
   throw new ERR_VM_DYNAMIC_IMPORT_CALLBACK_MISSING();
 }
 
-// This is configured during pre-execution. Specifically it's set to true for
-// the loader worker in internal/main/worker_thread.js.
 let _isLoaderWorker = false;
+/**
+ * Initializes handling of ES modules.
+ * This is configured during pre-execution. Specifically it's set to true for
+ * the loader worker in internal/main/worker_thread.js.
+ * @param {boolean} [isLoaderWorker=false] - A boolean indicating whether the loader is a worker or not.
+ */
 function initializeESM(isLoaderWorker = false) {
   _isLoaderWorker = isLoaderWorker;
   initializeDefaultConditions();
@@ -156,10 +181,17 @@ function initializeESM(isLoaderWorker = false) {
   setImportModuleDynamicallyCallback(importModuleDynamicallyCallback);
 }
 
+/**
+ * Determine whether the current process is a loader worker.
+ * @returns {boolean} Whether the current process is a loader worker.
+ */
 function isLoaderWorker() {
   return _isLoaderWorker;
 }
 
+/**
+ * Register module customization hooks.
+ */
 async function initializeHooks() {
   const customLoaderURLs = getOptionValue('--experimental-loader');
 
diff --git a/lib/internal/modules/esm/worker.js b/lib/internal/modules/esm/worker.js
index 5ff9ca4e87a415..433cb9446a2897 100644
--- a/lib/internal/modules/esm/worker.js
+++ b/lib/internal/modules/esm/worker.js
@@ -32,6 +32,11 @@ const {
 const { initializeHooks } = require('internal/modules/esm/utils');
 const { isMarkedAsUntransferable } = require('internal/buffer');
 
+/**
+ * Transfers an ArrayBuffer, TypedArray, or DataView to a worker thread.
+ * @param {boolean} hasError - Whether an error occurred during transfer.
+ * @param {ArrayBuffer | TypedArray | DataView} source - The data to transfer.
+ */
 function transferArrayBuffer(hasError, source) {
   if (hasError || source == null) { return; }
   let arrayBuffer;
@@ -47,6 +52,11 @@ function transferArrayBuffer(hasError, source) {
   }
 }
 
+/**
+ * Wraps a message with a status and body, and serializes the body if necessary.
+ * @param {string} status - The status of the message.
+ * @param {unknown} body - The body of the message.
+ */
 function wrapMessage(status, body) {
   if (status === 'success' || body === null ||
      (typeof body !== 'object' &&
@@ -73,6 +83,14 @@ function wrapMessage(status, body) {
   };
 }
 
+/**
+ * Initializes a worker thread for a customized module loader.
+ * @param {SharedArrayBuffer} lock - The lock used to synchronize communication between the worker and the main thread.
+ * @param {MessagePort} syncCommPort - The message port used for synchronous communication between the worker and the
+ * main thread.
+ * @param {(err: Error, origin?: string) => void} errorHandler - The function to use for uncaught exceptions.
+ * @returns {Promise<void>} A promise that resolves when the worker thread has been initialized.
+ */
 async function customizedModuleWorker(lock, syncCommPort, errorHandler) {
   let hooks;
   let initializationError;
@@ -114,6 +132,9 @@ async function customizedModuleWorker(lock, syncCommPort, errorHandler) {
   AtomicsNotify(lock, WORKER_TO_MAIN_THREAD_NOTIFICATION);
 
   let immediate;
+  /**
+   * Checks for messages on the syncCommPort and handles them asynchronously.
+   */
   function checkForMessages() {
     immediate = setImmediate(checkForMessages).unref();
     // We need to let the event loop tick a few times to give the main thread a chance to send
@@ -147,6 +168,13 @@ async function customizedModuleWorker(lock, syncCommPort, errorHandler) {
     setImmediate(() => {});
   });
 
+  /**
+   * Handles incoming messages from the main thread or other workers.
+   * @param {object} options - The options object.
+   * @param {string} options.method - The name of the hook.
+   * @param {Array} options.args - The arguments to pass to the method.
+   * @param {MessagePort} options.port - The message port to use for communication.
+   */
   async function handleMessage({ method, args, port }) {
     // Each potential exception needs to be caught individually so that the correct error is sent to
     // the main thread.
@@ -205,11 +233,19 @@ async function customizedModuleWorker(lock, syncCommPort, errorHandler) {
 }
 
 /**
+ * Initializes a worker thread for a module with customized hooks.
  * ! Run everything possible within this function so errors get reported.
+ * @param {{lock: SharedArrayBuffer}} workerData - The lock used to synchronize with the main thread.
+ * @param {MessagePort} syncCommPort - The communication port used to communicate with the main thread.
  */
 module.exports = function setupModuleWorker(workerData, syncCommPort) {
   const lock = new Int32Array(workerData.lock);
 
+  /**
+   * Handles errors that occur in the worker thread.
+   * @param {Error} err - The error that occurred.
+   * @param {string} [origin='unhandledRejection'] - The origin of the error.
+   */
   function errorHandler(err, origin = 'unhandledRejection') {
     AtomicsAdd(lock, WORKER_TO_MAIN_THREAD_NOTIFICATION, 1);
     AtomicsNotify(lock, WORKER_TO_MAIN_THREAD_NOTIFICATION);
diff --git a/lib/internal/modules/helpers.js b/lib/internal/modules/helpers.js
index 307a34cb09b512..cc32e95c4eb413 100644
--- a/lib/internal/modules/helpers.js
+++ b/lib/internal/modules/helpers.js
@@ -37,7 +37,13 @@ let debug = require('internal/util/debuglog').debuglog('module', (fn) => {
   debug = fn;
 });
 
+/** @typedef {import('internal/modules/cjs/loader.js').Module} Module */
+
+/** @type {Set<string>} */
 let cjsConditions;
+/**
+ * Define the conditions that apply to the CommonJS loader.
+ */
 function initializeCjsConditions() {
   const userConditions = getOptionValue('--conditions');
   const noAddons = getOptionValue('--no-addons');
@@ -51,6 +57,9 @@ function initializeCjsConditions() {
   ]);
 }
 
+/**
+ * Get the conditions that apply to the CommonJS loader.
+ */
 function getCjsConditions() {
   if (cjsConditions === undefined) {
     initializeCjsConditions();
@@ -58,27 +67,45 @@ function getCjsConditions() {
   return cjsConditions;
 }
 
-function loadBuiltinModule(filename, request) {
-  if (!BuiltinModule.canBeRequiredByUsers(filename)) {
+/**
+ * Provide one of Node.js' public modules to user code.
+ * @param {string} id - The identifier/specifier of the builtin module to load
+ * @param {string} request - The module requiring or importing the builtin module
+ */
+function loadBuiltinModule(id, request) {
+  if (!BuiltinModule.canBeRequiredByUsers(id)) {
     return;
   }
-  const mod = BuiltinModule.map.get(filename);
+  /** @type {import('internal/bootstrap/realm.js').BuiltinModule} */
+  const mod = BuiltinModule.map.get(id);
   debug('load built-in module %s', request);
   // compileForPublicLoader() throws if canBeRequiredByUsers is false:
   mod.compileForPublicLoader();
   return mod;
 }
 
+/** @type {Module} */
 let $Module = null;
+/**
+ * Import the Module class on first use.
+ */
 function lazyModule() {
   $Module = $Module || require('internal/modules/cjs/loader').Module;
   return $Module;
 }
 
-// Invoke with makeRequireFunction(module) where |module| is the Module object
-// to use as the context for the require() function.
-// Use redirects to set up a mapping from a policy and restrict dependencies
+/**
+ * Invoke with `makeRequireFunction(module)` where `module` is the `Module` object to use as the context for the
+ * `require()` function.
+ * Use redirects to set up a mapping from a policy and restrict dependencies.
+ */
 const urlToFileCache = new SafeMap();
+/**
+ * Create the module-scoped `require` function to pass into CommonJS modules.
+ * @param {Module} mod - The module to create the `require` function for.
+ * @param {ReturnType<import('internal/policy/manifest.js').Manifest['getDependencyMapper']>} redirects
+ * @typedef {(specifier: string) => unknown} RequireFunction
+ */
 function makeRequireFunction(mod, redirects) {
   // lazy due to cycle
   const Module = lazyModule();
@@ -86,6 +113,7 @@ function makeRequireFunction(mod, redirects) {
     throw new ERR_INVALID_ARG_TYPE('mod', 'Module', mod);
   }
 
+  /** @type {RequireFunction} */
   let require;
   if (redirects) {
     const id = mod.filename || mod.id;
@@ -131,6 +159,11 @@ function makeRequireFunction(mod, redirects) {
     };
   }
 
+  /**
+   * The `resolve` method that gets attached to module-scope `require`.
+   * @param {string} request
+   * @param {Parameters<Module['_resolveFilename']>[3]} options
+   */
   function resolve(request, options) {
     validateString(request, 'request');
     return Module._resolveFilename(request, mod, false, options);
@@ -138,6 +171,10 @@ function makeRequireFunction(mod, redirects) {
 
   require.resolve = resolve;
 
+  /**
+   * The `paths` method that gets attached to module-scope `require`.
+   * @param {string} request
+   */
   function paths(request) {
     validateString(request, 'request');
     return Module._resolveLookupPaths(request, mod);
@@ -159,6 +196,7 @@ function makeRequireFunction(mod, redirects) {
  * Remove byte order marker. This catches EF BB BF (the UTF-8 BOM)
  * because the buffer-to-string conversion in `fs.readFileSync()`
  * translates it to FEFF, the UTF-16 BOM.
+ * @param {string} content
  */
 function stripBOM(content) {
   if (StringPrototypeCharCodeAt(content) === 0xFEFF) {
@@ -167,6 +205,11 @@ function stripBOM(content) {
   return content;
 }
 
+/**
+ * Add built-in modules to a global or REPL scope object.
+ * @param {Record<string, unknown>} object - The object such as `globalThis` to add the built-in modules to.
+ * @param {string} dummyModuleName - The label representing the set of built-in modules to add.
+ */
 function addBuiltinLibsToObject(object, dummyModuleName) {
   // Make built-in modules available directly (loaded lazily).
   const Module = require('internal/modules/cjs/loader').Module;
@@ -227,9 +270,8 @@ function addBuiltinLibsToObject(object, dummyModuleName) {
 }
 
 /**
- *
+ * If a referrer is an URL instance or absolute path, convert it into an URL string.
  * @param {string | URL} referrer
- * @returns {string}
  */
 function normalizeReferrerURL(referrer) {
   if (typeof referrer === 'string' && path.isAbsolute(referrer)) {
@@ -238,7 +280,10 @@ function normalizeReferrerURL(referrer) {
   return new URL(referrer).href;
 }
 
-// For error messages only - used to check if ESM syntax is in use.
+/**
+ * For error messages only, check if ESM syntax is in use.
+ * @param {string} code
+ */
 function hasEsmSyntax(code) {
   debug('Checking for ESM syntax');
   const parser = require('internal/deps/acorn/acorn/dist/acorn').Parser;
diff --git a/lib/internal/modules/run_main.js b/lib/internal/modules/run_main.js
index 7636d27f3aee71..ac1ffef0412b17 100644
--- a/lib/internal/modules/run_main.js
+++ b/lib/internal/modules/run_main.js
@@ -7,6 +7,10 @@ const {
 const { getOptionValue } = require('internal/options');
 const path = require('path');
 
+/**
+ * Get the absolute path to the main entry point.
+ * @param {string} main Entry point path
+ */
 function resolveMainPath(main) {
   // Note extension resolution for the main entry point can be deprecated in a
   // future major.
@@ -23,6 +27,10 @@ function resolveMainPath(main) {
   return mainPath;
 }
 
+/**
+ * Determine whether the main entry point should be loaded through the ESM Loader.
+ * @param {string} mainPath Absolute path to the main entry point
+ */
 function shouldUseESMLoader(mainPath) {
   /**
    * @type {string[]} userLoaders A list of custom loaders registered by the user
@@ -43,6 +51,10 @@ function shouldUseESMLoader(mainPath) {
   return pkg && pkg.data.type === 'module';
 }
 
+/**
+ * Run the main entry point through the ESM Loader.
+ * @param {string} mainPath Absolute path to the main entry point
+ */
 function runMainESM(mainPath) {
   const { loadESM } = require('internal/process/esm_loader');
   const { pathToFileURL } = require('internal/url');
@@ -54,6 +66,10 @@ function runMainESM(mainPath) {
   }));
 }
 
+/**
+ * Handle process exit events around the main entry point promise.
+ * @param {Promise} promise Main entry point promise
+ */
 async function handleMainPromise(promise) {
   const {
     handleProcessExit,
@@ -66,9 +82,12 @@ async function handleMainPromise(promise) {
   }
 }
 
-// For backwards compatibility, we have to run a bunch of
-// monkey-patchable code that belongs to the CJS loader (exposed by
-// `require('module')`) even when the entry point is ESM.
+/**
+ * Parse the CLI main entry point string and run it.
+ * For backwards compatibility, we have to run a bunch of monkey-patchable code that belongs to the CJS loader (exposed
+ * by `require('module')`) even when the entry point is ESM.
+ * @param {string} main CLI main entry point string
+ */
 function executeUserEntryPoint(main = process.argv[1]) {
   const resolvedMain = resolveMainPath(main);
   const useESMLoader = shouldUseESMLoader(resolvedMain);