No fuss, no Muss.
Everytime I set up a new ubuntu 14.04 server and I want nodejs globally installed I have to go hunting.
So this just fixes everything.
# hope you ran with sudo
sudo apt-get update
sudo apt-get install curl -y
# gets the nodesource repo so you can easily install latest version
curl -sL https://deb.nodesource.com/setup | sudo bash -
# Install that nodejs
sudo apt-get install nodejs build-essential
# Finally..
node -v
npm -v