PHP JS Transform date to user timezone - php

Question

I have a page that shows future events along with the date (server time).
I need some method to display the date in user time.
Example:
Oct, 26 13:48:23 (server)
Oct, 26 14:48:23 (user time (UTC +1)) -> event info
What I have so far:
<?php
$sql=mysql_query("SELECT * FROM table") or die("Come back later");
while($row=mysql_fetch_array($sql)) {
echo date('M, d H:i:s', strtotime ($row['date'])).' -> '.$row['info'];
}
?>
With the diffence I want to detect user timezone.
Thank you.
EDIT
I know I should not be using mysql_*

Answer 1

If you're ok with doing the conversion to the user's time zone in JavaScript, you could do the following:
PHP
<?php
$sql=mysql_query("SELECT * FROM table") or die("Come back later");
while($row=mysql_fetch_array($sql)) {
echo '<span class="date">' . date('M, d H:i:s', strtotime ($row['date'])) . ' UTC</span> -> '.$row['info'];
}
?>
JavaScript (With jQuery for Readability)
$(function(){
$('.date').each(function(){
var $this = $(this);
// Parse the date string (the format you've given will
// work, and the added UTC above will give JavaScript
// some context)
var dateVal = new Date($this.text());
// JavaScript will convert it to the user's timezone when
// stringifying it (helped by the server timezone specified
// in the PHP.
$this.text(dateVal.toString());
});
});
If you want to render the dates in the format: Oct, 26 13:48:23, you could do this:
var dateString = dateVal.toLocaleString();
var parts = /^\w+ (\w+ \d{1,2}) \d{4} (\d{2}:\d{2}:\d{2})/.exec(dateString);
dateString = parts[1] + ' ' + parts[2];
Then use $this.text(dateString); to inject it into the dom.

Answer 2

You need to create DateTime object from this date, and then apply DateTimeZone to that object.

Answer 3

You would need to get the timezone from the user.
You can accomplish this by offering a dropdown with timezones that the user can select and submit. To make this a little more user friendly you could use some of the geoip functions to detect country and region and then determine a default timezone for the user. Do keep in my that location by IP is not 100% accurate but is instead an educated guess as to where the user may be located.
Alternatively you can use ajax to send the timezone to the server and then update accordingly.