How to have a CommonJS module execute its main() (as in Python)?

I wonder if a method exists that would run a predefined function in a CommonJS module (as those used开发者_如何转开发 in Node.js). I wrote a couple of node modules that act as services/servers. I can run them from inside a "controller script" executing their respective main() method, but I'd like also to call them by itself, like we are used to do in python.

I think the way is to try to understand if the module has been REQUIREd or not.

Do you know how?

This is the equivalent in Python

if __name__ == "__main__":
   print "Running standalone"

if (require.main === module) {
    console.log("running standalone");
}

accessing the main module