Assuming a debuggable version of your app, you should be able to use Chrome (for Android) and Safari (for iOS) to remotely inspect the app on your device. The device will need to be tethered and properly configured to allow remote debugging.
Alternatively, use PhoneGap's debugging option (which uses Weinre). It's not a full debugger, but should log `console.log` statements just fine.
See Debugging | PhoneGap Docs for more.