(function ($) {
    $.fn.scrollLoading = function (options) {
        var defaults = {
            attr: "data-original",
            container: $(window),
            callback: $.noop
        };
        var params = $.extend({}, defaults, options || {});
        params.cache = [];
        $(this).each(function () {
            var node = this.nodeName.toLowerCase(),
                url = $(this).attr(params["attr"]);
            //重组
            var data = {
                obj: $(this),
                tag: node,
                url: url
            };
            params.cache.push(data);
        });

        var callback = function (call) {
            if ($.isFunction(params.callback)) {
                params.callback.call(call.get(0));
            }
        };
        //动态显示数据
        var loading = function () {

            var contHeight = params.container.height();
            if ($(window).get(0) === window) {
                contop = $(window).scrollTop();
            } else {
                contop = params.container.offset().top;
            }

            $.each(params.cache, function (i, data) {
                var o = data.obj,
                    tag = data.tag,
                    url = data.url,
                    post, posb;

                if (o) {
                    post = o.offset().top - contop, post + o.height();

                    if (o.is(':visible') && (post >= 0 && post < contHeight) || (posb > 0 && posb <= contHeight)) {
                        if (url) {
                            //在浏览器窗口内
                            if (tag === "img") {
                                //图片，改变src
                                callback(o.attr("src", url));
                            } else {
                                o.load(url, {}, function () {
                                    callback(o);
                                });
                            }
                        } else {
                            // 无地址，直接触发回调
                            callback(o);
                        }
                        data.obj = null;
                    }
                }
            });
        };

        //事件触发
        //加载完毕即执行
        loading();
        //滚动执行
        params.container.bind("scroll", loading);
    };
})(jQuery);