前端利用xhr发起请求获取网络时间

获取网络时间，本质是利用ajax发起请求时，获取请求头上的时间戳。
简单封装一个xhr对象发起请求:

var time = ''

// 获取网络时间

var xhr = new XMLHttpRequest();

if( !xhr ){

   xhr = new ActiveXObject("Microsoft.XMLHTTP");

}

xhr.open("HEAD",location.href,true);

xhr.onreadystatechange=function(){

    if( xhr.readyState == 4 && xhr.status == 200 ){

         console.log('netWorkTime: ',xhr.getResponseHeader("Date"));

         time = xhr.getResponseHeader("Date")

         // console.log(dateTimeFormate(xhr.getResponseHeader("Date")));

        console.log( 'datatime',dateTimeFormate(time));

    }

}

xhr.send(null);

  


// 格式化时间

function dateTimeFormate(date){

    if(!date){

      return

    }else{

      var d = new Date(date);

      var year = d.getFullYear();

      var month = ('0' + (d.getMonth() + 1)).slice(-2);

      var day = ('0' + (d.getDate())).slice(-2);

      var hour = ('0' + (d.getHours())).slice(-2);

      var minutes = ('0' + (d.getMinutes())).slice(-2);

      var seconds = ('0' + (d.getSeconds())).slice(-2);

      return year + "-" + month + "-" + day + " " + hour + ":" + minutes + ":" + seconds;

    }

  }