get time from server and run it from there in javascript
var serverTime = 1490856278000;
var expected = serverTime;
var date;
var h;
var m;
var s;
var now = performance.now();
var then = now;
var dt = 0;
var nextInterval = (interval = 1000);
setTimeout(step, interval);
function step() {
then = now;
now = performance.now();
dt = now - then - nextInterval;
nextInterval = interval - dt;
serverTime += interval;
date = new Date(serverTime);
h = date.getHours();
m = date.getMinutes();
s = date.getSeconds();
var session = "AM";
if (h == 0) {
h = 12;
}
if (h > 12) {
h = h - 12;
session = "PM";
}
h = h < 10 ? "0" + h : h;
m = m < 10 ? "0" + m : m;
s = s < 10 ? "0" + s : s;
var time = h + ":" + m + ":" + s + " " + session;
document.getElementById("NowTime").innerHTML = time;
now = performance.now();
setTimeout(step, Math.max(0, nextInterval));
}