how to determine broadcast IP?

[josh-m-sharpe]

It seems that if I manually get the current broadcast IP of my network (ifconfig etc...) and hardcode that into a call to send() https://developer.chrome.com/apps/sockets_udp#method-send then packets get delivered to all devices on the network - which is great.

How do I dynamically determine what the current broadcast IP address is from a cordova device (ios/android)?