js判断网络连通性

if (window.navigator.onLine == true) {

                        console.log("首次 -- 已连接")

                        $.ajax({

                            url: "https://www.baidu.com/",

                            type: "POST",

                            timeout: 1000,

                            dataType: "json",

                        }).complete(function (XMLHttpRequest) {

                            console.log(XMLHttpRequest);

                            if (XMLHttpRequest.status == 200) {

                                $notification.show("已经可以正常上网", !0);

                            } else {

                                console.log("准备打开上网认证界面");

                                window.open(e, i);

                            }

                        });

                    } else {

                        $notification.show("网络未连接--请检查网络");

                    }