User timezone detection

gistfile1.php

<?php
	
// CLIENTSIDE:
	
if (!Yii::app()->user->timezone): ?>
	<script type="text/javascript">
		$(function () {
			var visitortime = new Date();
			$.ajax({
				type: "GET",
				url: "/user/settimezone",
				data: {
					name: /\((.*)\)/.exec(visitortime.toString())[1],
					offset: -visitortime.getTimezoneOffset() / 60
				}
			});
		});
	</script>
<?php endif; ?>
	

<?php
	
// SERVER SIDE:

	/**
	 * Set user timezone.
	 * @param string $name
	 * @param integer $offset
	 * @throws \CHttpException
	 */
	public function actionSetTimezone($name, $offset)
	{
		if (!Yii::app()->request->getIsAjaxRequest())
		{
			throw new \CHttpException(400);
		}

		$offset    = intval($offset) * 3600;
		$time_zone = timezone_name_from_abbr($name, $offset, false) ? : 'UTC';

		Yii::app()->setTimeZone($time_zone);
		Yii::app()->user->timezone = $time_zone;
	}