I am trying to get the windows username of the machine that is running my node.jS app (the app is always running on a Windows machine).
How can I get the current windows
I understand that this will not give the client user of a web app as OP asked, but this question is very high in the search results for trying to get the logged in user when running a Node application locally.
You can reproduce the output of whoamI and WindowsIdentity.GetCurrent() with environment variables in Windows.
process.env.USERDOMAIN + '\\' + process.env.USERNAME
If you'd rather use USERPROFILE:
process.env.USERDOMAIN + '\\' + process.env.USERPROFILE.split('\\').pop()