function Property() {
var xmlhttp;
if (window.XMLHttpRequest) {
xmlhttp = new XMLHttpRequest();
} else {
xmlhttp = new ActiveXObject("Microsoft .XMLHTTP");
 }
    
 xmlhttp.onreadystatechange = function() {
  if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
   var datastr = xmlhttp .responseText;
   alert(datastr);
   var dataobj = JSON.parse(datastr)
   let dataarr = [];
   for (let i in dataobj) {
    dataarr.push( dataobj[i]);
   }
#   
   
  }
 }
# 
 xmlhttp.open("POST", "https://api.123321yun.com/api /device/queryProjectDeviceParamStatus?projId=66", true);

/* xmlhttp.open("POST", "https://api.123321yun.com/api/user/login?username=test123&password= 123456", true);*/ xmlhttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
xmlhttp.send(); 
}

小白求解决登录状态无法保存的问题