(function () {  //图片预加载，promise
        $.preLoadImg = function () {
            var params = $.isArray(arguments[0]) ? arguments[0] : [].slice.call(arguments);
            var proArr = params.map(function (ele) {
                return getPromise(ele);
            });
            return $.when.apply($.when, params);  //Deferred 异步
        }
        function getPromise(src) {
            var img = document.createElement("img");
            var dfd = $.Deferred();
            img.onload = function () {
                dfd.resolve(this);
            };
            img.onerror = function () {
                dfd.reject(this);
            };
            img.src = src;
            return dfd;
        }
    })();

    var arr = ["/Content/images/1.jpg",
        "/Content//images/2d.jpg",
        "/Content/images/logo.jpg",
        "/Content/images/o_header_bg_cloude.jpg"];

    $.preLoadImg(arr).progress(function (img) {
        console.log("progress..." + img.src);
    }).fail(function (img) {
        console.log("error..." + img.src);
    }).done(function () {
        console.log("finish");
    });