Note: iOS 7+ does not permit apps to access the mac address. If you try, you'll get a nonsense value that doesn't mean anything.
What is your use case for using a mac address? If it's just as a uniqie ID, there are better ways to get something that will do. Apple (and others) view using the mac address in this manner as a privacy concern, which is why they limit the API.
AFAIK, there are some plugins that will work regarding mac address on the Cordova plugin repository (http://plugins.cordova.io), but just understand that they won't work for iOS.