nodejs · nodejs-github-bot · Jul 8, 2022 · Jun 14, 2022 · Jun 14, 2022 · Jun 14, 2022
diff --git a/doc/api/module.md b/doc/api/module.md
@@ -62,6 +62,22 @@ const require = createRequire(import.meta.url);
 const siblingModule = require('./sibling-module');
 ```
 
+### `module.isBuiltIn(moduleName)`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+* `moduleName` {string} name of the module
+* Returns: {boolean} returns true if the module is builtin else returns false
+
+```mjs
+import { isBuiltIn } from 'node:module';
+isBuiltIn('node:fs'); // true
+isBuiltIn('fs'); // true
+isBuiltIn('wss'); // false
+```
+
 ### `module.syncBuiltinESMExports()`
 
 <!-- YAML

diff --git a/lib/internal/modules/cjs/loader.js b/lib/internal/modules/cjs/loader.js
@@ -51,6 +51,7 @@ const {
   RegExpPrototypeExec,
   RegExpPrototypeTest,
   SafeMap,
+  SafeSet,
   SafeWeakMap,
   String,
   StringPrototypeCharAt,
@@ -188,6 +189,11 @@ for (const { 0: id, 1: mod } of NativeModule.map) {
   }
 }
 
+let allBuiltins = builtinModules.slice();
+builtinModules.forEach((builtin) => allBuiltins.push(`node:${builtin}`));
+allBuiltins = new SafeSet(allBuiltins);
+NativeModule.getSchemeOnlyModuleNames().forEach((builtin) => allBuiltins.add(`node:${builtin}`));
+
 ObjectFreeze(builtinModules);
 Module.builtinModules = builtinModules;
 
@@ -1293,5 +1299,9 @@ Module.syncBuiltinESMExports = function syncBuiltinESMExports() {
   }
 };
 
+Module.isBuiltIn = function isBuiltIn(moduleName) {
+  return allBuiltins.has(moduleName);
+};
+
 // Backwards compatibility
 Module.Module = Module;
diff --git a/test/parallel/test-module-isBuiltIn.js b/test/parallel/test-module-isBuiltIn.js
@@ -0,0 +1,16 @@
+'use strict';
+require('../common');
+const assert = require('assert');
+const { isBuiltIn } = require('module');
+
+// Includes modules in lib/ (even deprecated ones)
+assert(isBuiltIn('http'));
+assert(isBuiltIn('sys'));
+assert(isBuiltIn('node:fs'));
+assert(isBuiltIn('node:test'));
+
+// Does not include internal modules
+assert(!isBuiltIn('internal/errors'));
+assert(!isBuiltIn('test'));
+assert(!isBuiltIn(''));
+assert(!isBuiltIn(undefined));