if you have a wii u, just go here
http://www.nintendo.com/wiiu/built-in-software/browser-specs/sample/
for other information, rewind back to here
http://www.nintendo.com/wiiu/built-in-software/browser-specs/extended-functionality/
as you can see in the first link, you can get i think, absolutely everything on the gamepad. including, how far or small the control stick is, and the rotations of the gamepad. even + and -. even the analog stick click down thing. this is kind of cool just to use on the gamepad too. i dont know how to access the data in english, but as you can see, it is possible. or should be.
this, this really makes me want to make wii u browser games instead of 3ds browser games. getting absolutely every control is a browser game changer. even computer games wont have as many controls then this. this is pretty awesome. not to mention, the touch screen response is instant.
Yeah even though I don't have a Wii U I can tell you that even with mobile they added a lot of JavaScript API to access the features of the phone/tablet so the browser can take advantage of it. But it's good to see that they did add more support to the browser this time as the Wii U browser is basically the best Gaming Console browser.
i wouldnt say best though. for some reason, every single 3ds browser game i made is alot slower on the wii u browser then the 3ds browser. i really cannot imagine why though.