getSeconds() in JS returns seconds which are not equal to GMT seconds

Question

I use this code to show simple clock on my website:

function showClock() {
    var today = new Date(),
        h = today.getUTCHours(),
        m = today.getMinutes(),
        s = today.getSeconds();
    h = checkTime(h);
    m = checkTime(m);
    s = checkTime(s);

    $('.hour').html(h);
    $('.minutes').html(m);
    $('.seconds').html(s);

    setTimeout(showClock, 500);
}

function checkTime(i) {
    if (i < 10) {
        i = "0" + i;
    }
    return i;
}

I noticed that seconds which getSeconds() function returns are not equal to GMT seconds (I use http://wwp.greenwichmeantime.com/). How can I fix that? Maybe this question is quite strange, but I need your help!:)

Note that time zones can be offset by 15 or 30 minutes, so if you wish to show UTC time you must get at least UTC hours and UTC minutes. Seconds and milliseconds should be the same. — RobG, Mar 24 '16 at 05:33

score 0 · Answer 1 · answered Mar 23 '16 at 12:51

0

Date functions are based on the user's clock. Change your clock to 1980 and JavaScript will say it is 1980.

answered Mar 23 '16 at 12:51

Niet the Dark Absol

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score 0 · Answer 2 · answered Mar 23 '16 at 12:51

0

Just call getUTCSeconds instead of getSeconds.

answered Mar 23 '16 at 12:51

Qwertiy

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score 0 · Answer 3 · answered Mar 23 '16 at 13:02

Your system clock might be wrong.
You should use getUTCMinutes() and getUTCSeconds()
Depending on what you mean by "wrong" (maybe just slightly off?), you can improve your timer like this:

`

function showClock() {
  var today = new Date(),
    h = today.getUTCHours(),
    m = today.getUTCMinutes(),
    s = today.getUTCSeconds(),
    ms = today.getUTCMilliseconds();
  h = checkTime(h);
  m = checkTime(m);
  s = checkTime(s);

  console.log(h + ':' + m + ':' + s);

  setTimeout(showClock, 1000 - ms);
}

function checkTime(i) {
  if (i < 10) {
    i = "0" + i;
  }
  return i;
}

... which will try to always set up the timer so that it fires at actual second boundaries.

score 0 · Answer 4 · answered Mar 23 '16 at 13:04

0

Don't assume time zone offsets are always at hour boundaries. There are time zones at the 15 minute granularity (e.g. Chatham Islands in NZ). If you're using .getUTCHours(), you should use the corresponding UTC versions of minute and second getters.

answered Mar 23 '16 at 13:04

Ates Goral

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getSeconds() in JS returns seconds which are not equal to GMT seconds

4 Answers4