(function($) {
    var imgList = [];
    $.extend({
        preload: function(imgArr, option) {
            var setting = $.extend({
                init: function(loaded, total) {},
                loaded: function(img, loaded, total) {},
                loaded_all: function(loaded, total) {}
            }, option);
            var total = imgArr.length;
            var loaded = 0;
            var id = 0;
            setting.init(0, total);
            for(var i in imgArr) {
                imgList.push($("<img />")
                .attr("src", "/images/" + imgArr[i])
                .css("display","none")
                .attr("id","backimg" + id++)
                .attr("class","slideshow")
                .load(function() {
                    loaded++;
                    setting.loaded(this, loaded, total);
                    if(loaded == total) {
                        setting.loaded_all(loaded, total);
                    }
                })
            );
            }
        }
    });
})(jQuery);