update node to version 12 ubuntu code example

Example 1: update node ubuntu

sudo npm cache clean -f
sudo npm install -g n
sudo n stable

Example 2: ubuntu update nodejs

# Using Ubuntu
curl -sL https://deb.nodesource.com/setup_12.x | sudo -E bash -
sudo apt-get install -y nodejs

# Using Debian, as root
curl -sL https://deb.nodesource.com/setup_12.x | bash -
apt-get install -y nodejs