is-builtin-module 
Check if a string matches the name of a Node.js builtin module
Install
$ npm install --save is-builtin-module
Usage
var isBuiltinModule = require('is-builtin-module');
isBuiltinModule('fs');
//=> true
isBuiltinModule('unicorn');
//=> false :(
Related
- builtin-modules - List of the Node.js builtin modules
License
MIT © Sindre Sorhus