iPhone 5 6.1OS Javascript menus not working

prior to updating to 6.1 my phone worked great on a specific site I use for work to see schedules/orders. Now that I've uploaded to 6.1 these menus which are Javascript are not running. I have access to a 4s which updated to 6.1OS and the web site works fine? What's up? are the javascript librarys not upto date with the iPhone 5 running 6.1? How do I fix this seems to only be an issue on a iphone 5 in 6.1OS.