Can I know, in node.js, if my script is being run directly or being loaded by another script?
The accepted answer is fine. I'm adding this one from the official documentation for completeness:
Accessing the main module
When a file is run directly from Node, require.main is set to its module. That means that you can determine whether a file has been run directly by testing
require.main === moduleFor a file "foo.js", this will be true if run via node foo.js, but false if run by require('./foo').
Because module provides a filename property (normally equivalent to __filename), the entry point of the current application can be obtained by checking require.main.filename.
Both options !module.parent and require.main === module work.If you are interested in more details please read my detailed blog post about this topic.