$(window).on('resize', function () {
    $("img.CarouselImg").each(function () {
        var MyImgs = $(this).attr("imgdatasrc");
        var MyList = MyImgs.split(';');
        var MySize = getWindowSize();
        if (MySize.height > MySize.width) {
            // vertical 
            // (default value)
            // $(this).attr("src", MyList[2]);
        } else {
            if (MySize.width > 1024) {
                // large
                $(this).attr("src", MyList[0]);
            } else {
                // medium
                $(this).attr("src", MyList[1]);
            }
        }
    });
});
$(document).ready(function () {
    $(window).trigger('resize');
});

var getWindowSize = (function () {
    var docEl = document.documentElement,
        IS_BODY_ACTING_ROOT = docEl && docEl.clientHeight === 0;

    // Used to feature test Opera returning wrong values 
    // for documentElement.clientHeight. 
    function isDocumentElementHeightOff() {
        var d = document,
            div = d.createElement('div');
        div.style.height = "2500px";
        d.body.insertBefore(div, d.body.firstChild);
        var r = d.documentElement.clientHeight > 2400;
        d.body.removeChild(div);
        return r;
    }

    if (typeof document.clientWidth == "number") {
        return function () {
            return { width: document.clientWidth, height: document.clientHeight };
        };
    } else if (IS_BODY_ACTING_ROOT || isDocumentElementHeightOff()) {
        var b = document.body;
        return function () {
            return { width: b.clientWidth, height: b.clientHeight };
        };
    } else {
        return function () {
            return { width: docEl.clientWidth, height: docEl.clientHeight };
        };
    }
})();