checkNet().then(function(res) {    if(res) {        //连网成功            }    } else {        //连网失败                    }})

(function() {    //检测入口    checkNet = function() {        var def = $.Deferred();        xiuNet(null).then(function(res) {            netWork(null).then(function(res) {                if(res) {                    def.resolve(true);                } else {                    def.resolve(false);                }            })        })        return def.promise();    }        //嗅探网络，解决ios弹框接入网络问题    var checkTime = 2; //嗅探次数    xiuNet = function(def) {        if(def == null) {def = $.Deferred();}        var iframe = document.createElement("iframe");        iframe.style.cssText = "display:none;width:0px;height:0px;";        document.body.appendChild(iframe);        var ua = navigator.userAgent;        if(ua.indexOf("iPhone") != -1 || ua.indexOf("iPod") != -1 ||            ua.indexOf("iPad") != -1) {            iframe.src = "http://www.baidu.com" + "?timestap=" + new Date().getTime();            console.info("嗅探网络----");            if(checkTime > 1) {                checkTime--;                setTimeout(function() {                    xiuNet(def)                }, 1000);            } else {                def.resolve(true);            }        } else {            def.resolve(false);        }        return def.promise();    }    //检测网络，是否可以连接公网    var cnetTime = 3; //检测网络次数    netWork = function(def) {        if(def == null) {def = $.Deferred();}        $.ajax({            type: "get",            timeout: 2000,            dataType: "jsonp",            jsonp: "callback",            url: ‘https://jktv.tv/shphone/ver.txt‘,            success: function(data) {},            error: function(xhr) {                $("#ddd").html("status:"+xhr.status)                if(xhr.readyState == 4 && xhr.status == 200) {                    def.resolve(true);                } else {                    if(cnetTime > 1) {                        cnetTime--;                        setTimeout(function() {                            netWork(def)                        }, 200);                    } else {                        def.resolve(false);                    }                }            }        });        return def.promise();    }})();