yState == 4) {
                var text = xmlhttp.responseText;
                var cargoEvent = JSON.parse(text);
                console.log(cargoEvent);
                document.getElementById("cargoId").innerHTML = "单号：" + cargoEvent.cargo.id;
                document.getElementById("senderPhone").innerHTML = "发件人：" + cargoEvent.cargo.senderPhone;
                document.getElementById("description").innerHTML = "描述：" + cargoEvent.cargo.description;
                document.getEleme