To keep it simple, how do I debug my code running on a device?
The problem I am facing is that the game runs on desktop browser, iphone4,4s,5 browsers but doesn’t even load on iphone3GS and itouch4. The game is stuck on the loading screen at 99% 
If you want to debug the game from your computer you can go to the Settings~~>Safari~~>Advanced and activate Web Inspector on your iPhone. After that you can connect your iphone to your computer by USB and use the Develop->iPhone menu alternative from Safari on your computer.