How do I show the current GMT (time) using Javascript on my website

I have a script that I use to display the data/time on a website. This works ok but just works off the users/browser time.

On something new I’m working on, I’d like it to display the time in a specific timezone (GMT) always – is that possible?

I don’t need the month in this version, so you can see that commented out.

As an aside, even on the original version. The time ‘jumps’ into view as it takes a while to load – is there away to fix this?

Might be worth noting this is a simple static website, so no database or much else to play with to get the time.

Cheers!

function showDateTime() {
    var currentDate = document.getElementById("date");
    var currentTime = document.getElementById("time");
    
    var date = new Date();
    var dayList = ["Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"];
    /* var monthNames = ["Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"]; */
    var dayName = dayList[date.getDay()];
    /* var monthName = monthNames[date.getMonth()]; */
    /* var today = `${dayName} ${date.getDate()} ${monthName}`; */
    var today = `${dayName}`;
    
    var hour = ('0' + date.getHours()).substr(-2);
    var min = ('0' + date.getMinutes()).substr(-2);
    var sec = ('0' + date.getSeconds()).substr(-2);
    
    
    var time = hour + ":" + min + ":" + sec;
    currentDate.innerText = `${today}`;
    currentTime.innerText = `${time}`;
}
setInterval(showDateTime, 1000);

<p><span id="date" class="os-menu__item"></span> <span id="time"></span> GMT</p>