Detect Wii U button input in HTML

Question

I'm trying to get a website to detect a button input from the Wii U gamepad. When I press a button, nothing happens. Here is some documentation on the Wii U Browser. Also, here. Here is my code:

function reset() {
    var A = document.getElementById("A");
    A.style.color = "black";
}

if (navigator.appVersion.indexOf("WiiU") != -1) { // = WiiU Browser
    var A = document.getElementById("A");

    // Register all values from GamePad.
    wiiu.gamepad.update();

    A.style.color = "black";

    if (wiiu.gamepad.hold == 0x00080000) // A
        A.style.color = "cyan";
}

Thanks!