var req = new XMLHttpRequest();
req.open('GET', document.location, false);
req.send('https://microsoft.com');
var dateGTM = new Date(req.getResponseHeader('date').replace( / GMT$/, "" ))
var timezone = 3; // Часовой пояс
var date = new Date(dateGTM.getTime() + timezone * 3600 * 1000)