Detect file run as main or module

There's a simple way in Python to know if current file is being run directly or as an import, using the __main__ variable. Any such way in Node.js?

Yes, there is.

CommonJS

if (require.main === module) {
  console.log('This file is being run directly.');
} else {
  console.log('This file is being imported as a module.');
}

ESM

// mainModule.mjs

if (import.meta.url === `file://${process.argv[1]}`) {
  console.log('This ESM module is being run directly.');
} else {
  console.log('This ESM module is being imported as a module.');
}

What's the use of this?

I write Node.js scripts for personal use, and it's good to have usage examples that console.log something. If a script is being run directly, it'll print the usage examples, otherwise it'll stay silent.