get the local network address of your machine
npm install network-address
it is easy to use
var address = require('network-address')
console.log(address()) // prints something like 192.168.3.102
console.log(address.ipv6()) // prints something like fc00::5137:ecb:55be:c2fc
it is also available as a command line tool
npm install -g network-address
you are now able to run network-address in your terminal