Upgrade nodejs via npm

Clean all npm cache from your system forcefully.

sudo npm cache clean -f 

After cleaning all cache from your system, now install n modules using npm command.

sudo npm install -g n 

Install Nodejs – Let’s install or update latest nodejs version on your system using n module

sudo n stable 

Updating npm

Node comes with npm installed so you should have a version of npm. However, npm gets updated more frequently than Node does, so you'll want to make sure it's the latest version.

npm install npm@latest -g