Is it possible to check for the iPad version (1 or 2) in a web application? As the user agent looks identical (see http://www.webtrends.com/Support/KnowledgeBase/SolutionDetail.aspx?Id=50140000000acbiAAA) a standard check by browser does not work here.
Can we check for features (like the gyroscope) in JavaScript which are only available in version 2?
Please try this fiddle. It detects version of iPad by gyroscope availability.
As you can see in Safari Developer Library, event.acceleration is not null on devices that has a gyroscope. Since iPad 1 doesn't has it, we can assume that this device is iPad 1.
To distinguish iPad 2 from iPad 3, we can check a window.devicePixelRatio property, since iPad 3 has Retina display with pixel ratio == 2.