$ sudo npm install which
$ sudo npm install -g which

If want to update the which package execute the command as below,

$ sudo npm update which

Update package globally,

$ npm install -g which

Git clone:

$ sudo  git clone https://github.com/rektide/which.git

$ sudo  npm install -g ./which

which@1.3.0 /usr/lib/node_modules/which

How to remove which package :

You can uninstall or remove this package from your node_modules run the command as below,

$ sudo npm uninstall which

Basic Information of which NPM Package: