I would use a normal url, which points to a web page where just that simple script runs. To enable offline capacibility just declare an HTML5 offline application manifest!
This way u only need internet the first time u use the QR code. It seems like u have a good control over the devices, so this shouldnt be a problem. At least less then a custom QR App!
For diffrent QR codes just use the hashtag #
in the url and do the rest in the JS. So its always the same Web Page and it can be loaded offline!