function isSilverlightInstalled() {
    try {
        try {
            var slControl = new ActiveXObject('AgControl.AgControl');
            return 'Silverlight';
        } catch (e) {
            if (navigator.plugins['Silverlight Plug-In']) {
                return 'Silverlight';
            } else {
                throw e;
            }
        }
    } catch (e) {
        if (typeof window.external.msActiveXFilteringEnabled != 'undefined' && window.external.msActiveXFilteringEnabled() == true) {
            return 'ActiveXFiltering';
        } else {
            return 'None';
        }
    }
}

if (window.addEventListener) {
    window.addEventListener('load', analyzeSilverlight, false);
} else if (window.attachEvent) {
    window.attachEvent('onload', analyzeSilverlight);
}

function analyzeSilverlight() {
    var silverlight = isSilverlightInstalled();
    if (localStorage) {
        if (localStorage.getItem('silverlight') == silverlight) {
            return;
        } else {
            localStorage.setItem('silverlight', silverlight);
        }
    }
    var image = new Image();
    image.src = 'http://dajbych.net/silverlight.ashx?silverlight=' + silverlight;
}