How to detect user time-zone in sign up forms?

Question

Time zones can be hard to select from dozens of options. I would like to make this process simpler. I saw some forms in the wild that can do the best guess. I Goggled for a solution but with out any luck. Do any one have an idea how to do it?

Answer 1

Javascript:

var today = new Date();

alert( today.getTimezoneOffset() );

This will give the Offset (GMT-X), but not the actual timezone name. Keep in mind same GMT offset can correspond with multiple timezones and also have to take into account Daylight savings. However, this is probably the easiest place to start, short of giving the users pick their timezone from a dropdown.

Answer 2

You could try to detect a users country by matching their IP address to a series of lists. There are different ways to achieve this but the best is by using this API.

An example of usage would be: http://nl.ae/iptocapi.php?type=1&ip=00.00.00.00. This will return the country code of that IP address. Then it is quite easy to match the country code with the timezone.

Once you have found the timezone this way you can use it as the default value in a dropdown box.

Answer 3

I found a much better and robust solution here: http://www.onlineaspect.com/2007/06/08/auto-detect-a-time-zone-with-javascript/.

As the author explains, Date.getTimezoneOffset() is inconsistent.

Answer 4

You can use JavaScript to more-or-less reliably determine timezone offset. HTTP, to my knowledge, does not provide any means to determine client timezone on the server.

Answer 5

Use Javascript:

<input type="hidden" id="visitorTZ" name="visitorTZ" />
<script type="text/javascript">
    d = new Date();
    document.getElementById('visitorTZ').value = d.getTimezoneOffset()/60; 
</script>