JavaScript Jquery检测是否加载了img

/*
 * Special event for image load events
 * Needed because some browsers does not trigger the event on cached images.

 * MIT License
 * Paul Irish     | @paul_irish | www.paulirish.com
 * Andree Hansson | @peolanha   | www.andreehansson.se
 * 2010.
 *
 * Usage:
 * $(images).bind('load', function (e) {
 *   // Do stuff on load
 * });
 * 
 * Note that you can bind the 'error' event on data uri images, this will trigger when
 * data uri images isn't supported.
 * 
 * Tested in:
 * FF 3+
 * IE 6-8
 * Chromium 5-6
 * Opera 9-10
 */
(function ($) {
    $.event.special.load = {
        add: function (hollaback) {
            if ( this.nodeType === 1 && this.tagName.toLowerCase() === 'img' && this.src !== '' ) {
                // Image is already complete, fire the hollaback (fixes browser issues were cached
                // images isn't triggering the load event)
                if ( this.complete || this.readyState === 4 ) {
                    hollaback.handler.apply(this);
                }

                // Check if data URI images is supported, fire 'error' event if not
                else if ( this.readyState === 'uninitialized' && this.src.indexOf('data:') === 0 ) {
                    $(this).trigger('error');
                }

                else {
                    $(this).bind('load', hollaback.handler);
                }
            }
        }
    };
}(jQuery));