How to get client's timezone?

Question

I'm writting an application using Zend_Framework (so the solution can rely on it).

How to get client's timezone?

For example, if someone in Moscow, Russia, I want to get 3*60*60 (because there is UTC+3). If he is in UK, I want zero. If he uses UTC-3:30 (Canada?), I want -3.5*60*60.

(it's not a question about a format - I'm ok with getting 'Europe/Moscow' or 'UTC-3' for St. Petersburg, Russia, it's rather about getting timezone client uses. But delta in seconds is preferred)

The only solution which comes to mind is letting javascript get the local time for me and redirect.

Answer 1

I wrote a function using jQuery and PHP. This is tested, and does work!

On the PHP page where you are want to have the timezone as a variable, have this snippet of code somewhere near the top of the page:

<?php    
    session_start();
    $timezone = $_SESSION['time'];
?>

This will read the session variable "time", which we are now about to create.

On the same page, in the , you need to first of all include jQuery:

<script type="text/javascript" src="http://code.jquery.com/jquery-latest.min.js"></script>

Also in the , below the jQuery, paste this:

<script type="text/javascript">
    $(document).ready(function() {
        if("<?php echo $timezone; ?>".length==0){
            var visitortime = new Date();
            var visitortimezone = "GMT " + -visitortime.getTimezoneOffset()/60;
            $.ajax({
                type: "GET",
                url: "http://domain.com/timezone.php",
                data: 'time='+ visitortimezone,
                success: function(){
                    location.reload();
                }
            });
        }
    });
</script>

You may or may not have noticed, but you need to change the url to your actual domain.

One last thing. You are probably wondering what the heck timezone.php is. Well, it is simply this: (create a new file called timezone.php and point to it with the above url)

<?php
    session_start();
    $_SESSION['time'] = $_GET['time'];
?>

If this works correctly, it will first load the page, execute the JavaScript, and reload the page. You will then be able to read the $timezone variable and use it to your pleasure! It returns the current UTC/GMT time zone offset (GMT -7) or whatever timezone you are in.

Answer 2

Check out this article on how to detect the timezone by setting a Cookie through JavaScript that will hold the client's timezone. It's rather lenghty, but that is because it is quite verbose. I've implemented a solution along these lines in one of my own apps and it works quite well.

You could also send the timezone via Ajax to the server and have it do whatever you need to do it with then. Or, if you are not doing any serverside calculations with it, just apply the timezone client side where needed. Really depends on your usecase.

In addition to that, I suggest you let the visitor set his timezone himself and store that in the Cookie or a Session.

Answer 3

This is a cookie solution with very little overhead:

  echo <<<EOE
   <script type="text/javascript">
     if (navigator.cookieEnabled)
       document.cookie = "tzo="+ (- new Date().getTimezoneOffset());
   </script>
EOE;
  if (!isset($_COOKIE['tzo'])) {
    echo <<<EOE
      <script type="text/javascript">
        if (navigator.cookieEnabled) document.reload();
        else alert("Cookies must be enabled!");
      </script>
EOE;
    die();
  }
  $ts = new DateTime('now', new DateTimeZone('GMT'));
  $ts->add(DateInterval::createFromDateString($_COOKIE['tzo'].' minutes'));

Answer 4

I think your best bet is to guess based on the Accept-Language header sent over by the client.