服务器时间

gistfile1.txt

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(xhr.getResponseHeader("Date"));  
    }  
}  
xhr.send(null);