Testing hardware support in Javascript for device orientation events of the iPhone 3GS

Question

I'm trying to use HTML5 deviceOrientation events in Javascript to rotate an image when the user rotate his iPhone around him.

I use this code to detect when the gyroscope is moving :

window.addEventListener('deviceorientation', function (e) {
    alpha = e.alpha;
    beta = e.beta;
    gamma = e.gamma;            
}, true);

It really works well on iPhone 4+ and iPad 2, but there's no gyroscope on the 3GS (and older iPhones). That's why I'm testing the deviceOrientationSupport like this :

if(window.DeviceOrientationEvent){ // gyroscope support
    alert('DeviceOrientationEvent support OK');
} else {
    alert('DeviceOrientationEvent support KO');
}

I've seen this code on many websites or forums, but my problem is that with my iPhone 3GS under IOS 5.0.1, this test indicates me : deviceOrientationSupport OK !

I think that this test check only if Safari is able to handle these events :(

So my question is, is it possible to add a test to know if the hardware can fire orientation events ?

Thanks !

Answer 1

After having the same issue as above I also had problems with the older iPad/iPhones not even calling the function on addEventListener.

So I found that the following worked a lot better for me and eliminated any chance of an unsupported device getting through (this was sat with a load screen so it did require an interval before completing its full test. So not for everyone).

var _i = null;
var _e = null;
var _c = 0;

var updateDegree = function(e){
    _e = e;
}

window.addEventListener('deviceorientation', updateDegree, false);

//  Check event support
_i = window.setInterval(function(){
    if(_e !== null && _e.alpha !== null){
        // Clear interval
        clearInterval(_i);
        // > Run app
    }else{
        _c++;
        if(_c === 10){
            // Clear interval
            clearInterval(_i);
            // > Redirect
        }
    }
}, 200);