Javascript获取服务器时间

<p id="time"></p>
<script>
ajax()
  function ajax(option){
    var xhr = null;
    if(window.XMLHttpRequest){
      xhr = new window.XMLHttpRequest();
    }else{ // ie
      xhr = new ActiveObject("Microsoft")
    }
    // 通过get的方式请求当前文件
    xhr.open("get","/");
    xhr.send(null);
    // 监听请求状态变化
    xhr.onreadystatechange = function(){
      var time = null,
          curDate = null;
      if(xhr.readyState===2){
        // 获取响应头里的时间戳
        time = xhr.getResponseHeader("Date");
        console.log(xhr.getAllResponseHeaders())
        curDate = new Date(time);
        document.getElementById("time").innerHTML = "服务器时间是："+curDate.getFullYear()+"-"+(curDate.getMonth()+1)+"-"+curDate.getDate()+" "+curDate.getHours()+":"+curDate.getMinutes()+":"+curDate.getSeconds();
      }
    }
  }
</script>

 <script>
function updateorder(username, status, starthour, endhour) {
        //Logger log = Logger.getLogger(this.getClass());
        var xhr = null;
        if (window.XMLHttpRequest) {
            xhr = new window.XMLHttpRequest();
        } else { // ie
            xhr = new ActiveObject("Microsoft")
        }
        // 通过get的方式请求当前文件
        xhr.open("get", "/javawebservlet/index.jsp");
        xhr.send(null);
        // 监听请求状态变化
        xhr.onreadystatechange = function () {
            var time = null;
            if (xhr.readyState === 2) {
                // 获取响应头里的时间戳
                time = xhr.getResponseHeader("Date");
                console.log(xhr.getAllResponseHeaders());
                var date = new Date(time);
                console.log("转换后的中国时间为： "+date)
                //1. 创建Date对象
//        var date = new Date();
                //5. 获得当前小时
                var hour = date.getHours();
                //6. 获得当前分钟
                var min = date.getMinutes();
                //7. 获得当前秒
                var sec = date.getSeconds();
//                alert(hour + ":" + min + ":" + sec);
                var curr = hour * 60 * 60 + min * 60 + sec;
                var startime = starthour * 60 * 60 + 30 * 60;
                var endtime = endhour * 60 * 60 + 15 * 60;
                var startimetext = "还没有到订餐时间！";
                var endtimetext = "吃饭不积极，订餐已经结束了！";
                if (username.length == 0) {
                    layer.msg(‘请重新登录！‘, {icon: 1, time: 3000});
                    //重定向，打开新页面同时把老页面关闭
                    window.top.location.href = "/javawebservlet/login.jsp"
                } else {
                    if (curr < startime) {
                        //alert("还没有开始");
                        layer.open({
                            type: 1
                            , offset: ‘auto‘
                            , id: ‘layerDemo‘ + 1 //防止重复弹出
                            , content: ‘<div style="padding: 20px 100px;">‘ + startimetext + ‘</div>‘
                            , btn: ‘关闭全部‘
                            , btnAlign: ‘c‘ //按钮居中
                            , shade: 0 //不显示遮罩
                            , yes: function () {
                                layer.closeAll();
                            }
                        });
                    } else if (curr > endtime) {
//            alert("已经结束");
                        layer.open({
                            type: 1
                            , offset: ‘auto‘
                            , id: ‘layerDemo‘ + 1 //防止重复弹出
                            , content: ‘<div style="padding: 20px 100px;">‘ + endtimetext + ‘</div>‘
                            , btn: ‘关闭全部‘
                            , btnAlign: ‘c‘ //按钮居中
                            , shade: 0 //不显示遮罩
                            , yes: function () {
                                layer.closeAll();
                            }
                        });
                    } else if (curr >= startime && curr <= endtime) {
                        layer.msg(‘订餐成功！‘, {icon: 1, time: 3000});
                        window.location.href = "/javawebservlet/UpdateStatusServlet?username=" + username + "&status=" + status;
                    }

                }

            }
        }
</script>
<span class="layui-btn layui-btn-normal layui-btn-mini" onclick=‘updateorder("${username}","1","15","18")‘>一起订餐</span>