$ sudo npm install firebase-functions
$ sudo npm install -g firebase-functions

If want to update the firebase-functions package execute the command as below,

$ sudo npm update firebase-functions

Update package globally,

$ npm install -g firebase-functions

Git clone:

$ sudo  git clone https://github.com/rektide/firebase-functions.git

$ sudo  npm install -g ./firebase-functions

firebase-functions@0.7.3 /usr/lib/node_modules/firebase-functions

How to remove firebase-functions package :

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

$ sudo npm uninstall firebase-functions

Basic Information of firebase-functions NPM Package: