Based on issues:
I think npm should have clear way for manage system-wide packages (packages available for all users in system on Windows)
Therefore npm should deal with three types of packages:
global for user (--global)
this type of installation is very useful for development and testing purposes
global for system (--system for example)
this type of installation needed in production environment
The system-wide installation should:
1) uses other path for packages (accessible for reading by all users in system).
2) uses system environment variable PATH to store path to executables.
The system-wide installation may require the administrator's rights for user that invoke npm --system
There are possible variants for path for system-wide installation (discussion need):
1) %PROGRAMDATA%/npm (absent in Windows XP)
3) Node's folder
It turns out we were just discussing this over on #6413, and have been discussing closely related issues on #4564. I think this would be a good idea – maybe – but it's also pretty far down the priority queue because it's a pretty dramatic change and thus at least a major version out. I'm not averse to looking at patches or discussing it further, though.