module: add isBuiltIn method

PR-URL: #43396
Fixes: #42785
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Ruben Bridgewater <[email protected]>
Reviewed-By: Michaël Zasso <[email protected]>
Reviewed-By: Anto Aravinth <[email protected]>
Reviewed-By: Juan José Arboleda <[email protected]>

Author: hemanth

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

lib/internal/modules/cjs/loader.js

@@ -33,6 +33,7 @@ const {
   ArrayPrototypeSplice,
   ArrayPrototypeUnshift,
   ArrayPrototypeUnshiftApply,
+  ArrayPrototypeFlatMap,
   Boolean,
   Error,
   JSONParse,
@@ -50,6 +51,7 @@ const {
   ReflectSet,
   RegExpPrototypeExec,
   SafeMap,
+  SafeSet,
   SafeWeakMap,
   String,
   StringPrototypeCharAt,
@@ -186,6 +188,11 @@ for (const { 0: id, 1: mod } of NativeModule.map) {
   }
 }
 
+const allBuiltins = new SafeSet(
+  ArrayPrototypeFlatMap(builtinModules, (bm) => [bm, `node:${bm}`])
+);
+NativeModule.getSchemeOnlyModuleNames().forEach((builtin) => allBuiltins.add(`node:${builtin}`));
+
 ObjectFreeze(builtinModules);
 Module.builtinModules = builtinModules;
 
@@ -1300,5 +1307,9 @@ Module.syncBuiltinESMExports = function syncBuiltinESMExports() {
   }
 };
 
+Module.isBuiltin = function isBuiltin(moduleName) {
+  return allBuiltins.has(moduleName);
+};
+
 // Backwards compatibility
 Module.Module = Module;

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));