Modulino pattern in Node.js

dependant.js

const x = require('./index.js')

dependant.mjs

import a from './index.mjs'

index.js

if (require.main === module) {
  console.log('called directly');
} else {
  console.log('required as a module');
}

index.mjs

import { fileURLToPath } from 'url'

export default function () { }

const isRunningDirectlyViaCLI = process.argv[1] === fileURLToPath(import.meta.url)

if (isRunningDirectlyViaCLI) {
  console.log('called directly');
} else {
  console.log('required as a module');
}