Clock in different time zones

Question

I am trying to create two clocks on a website that says two times on it. One from London and the other from New York.

I have been able to create a clock that reads the current time on my computer but i'm not sure how to place a time zone into this.

The code I have so far is:

<script type="text/javascript" language="javascript">

function renderTime() {
    var currentTime = new Date();
    var diem = "AM";
    var h = currentTime.getHours();
    var m = currentTime.getMinutes();
    var s = currentTime.getSeconds();

    if (h == 0) {
        h = 12
    } else if (h > 12) {
        h = h - 12;
        diem = "PM";
    }

    if (h < 10) {
        h = "0" + h;
    }

    if (m < 10) {
        m = "0" + m;
    }

    if (s < 10) {
        s = "0" + s;
    }

    var myClock = document.getElementById ("clockDisplay");
    myClock.textContent = h + ":" + m + ":" + s + " " + diem;

    setTimeout ('renderTime()', 1000);
}
renderTime();
</script>

This is being applied to a CSS style I have created so I can have the clock in a specific typeface.

Answer 1

currentTime.getTimezoneOffset() will give you the time difference between Greenwich Mean Time (GMT) and local time, in minutes.

You can use the value to calculate time in required timezone.

Answer 2

To do this properly, you will need a time zone database, such as one of the ones I listed here.

All of the other answers to this question are making the mistake in thinking that a "time zone" and a "time zone offset" are the same thing. They are not. For example, the time zone for London is Europe/London, which can have either a +0 or +1 offset depending on what time of year it is. The time zone for New York is America/New_York, which can have either a -5 or -4 offset based on a completely different set of dates than London.

You might want to look at moment-timezone:

moment().tz("America/New_York").format()