Using JavaScript to check if images are enabled

checkImage.js

(function() {
    var image = new Image();
    image.onload = function() {
        if (image.width > 0) {
            document.documentElement.className += (document.documentElement.className != '') ? ' images-on' : 'images-on';
        }
    };
    image.src = 'px.png';
}());

// http://www.456bereastreet.com/archive/201211/using_javascript_to_check_if_images_are_enabled/