Ravi Kiran Katha

<p>WordPress has a site-level timezone setting configured from the admin back-end. All dates and times displayed on the front-end are typically displayed in this timezone.</p>
<p>This plugin enables the display of dates/times in the front-end using the browser’s timezone. This is done by overriding the WordPress’s <strong>‘timezone_string’</strong> and <strong>‘gmt_offset’</strong> options to match the user’s timezone <strong>for the duration of a particular request</strong><br />
<strong>ONLY on the front-end interface</strong>.</p>
<h4>Browser Timezone Detection</h4>
<p>The browser’s timezone is detected using one of the following two methods</p>
<ol>
<li><a href="http://pellepim.bitbucket.org/jstz/" rel="nofollow ugc">jsTimezoneDetect</a> (default)</li>
<li><a href="http://caniuse.com/geolocation" rel="nofollow ugc">HTML5 Geolocation API</a> and <a href="https://developers.google.com/maps/documentation/timezone" rel="nofollow ugc">Google Timezone API</a></li>
</ol>
<p><strong>jsTimezoneDetect (default)</strong><br />
    This is the default timezone detection mechanism. Please refer to the script <a href="http://pellepim.bitbucket.org/jstz/" rel="nofollow ugc">home page</a><br />
for the compatibility and other notes</p>
<p><strong>HTML5 Geolocation API</strong><br />
    Detects the current geo-location using <em><a href="http://caniuse.com/geolocation" rel="nofollow ugc">navigator.geolocation.getCurrentPosition</a></em>. The location thus detected will be sent to the <a href="https://developers.google.com/maps/documentation/timezone" rel="nofollow ugc">Google Timezone API</a><br />
which returns the timezone id – similar to “Asia/Kolkata”.</p>
<p>This method requires you to</p>
<ul>
<li>Enable the “Google Timezone API” option on the plugin options page</li>
<li>Specify a valid <a href="https://developers.google.com/maps/documentation/timezone/get-api-key" rel="nofollow ugc">Google API Key</a>
<ul>
<li>The key should be a browser key</li>
<li>The “Accepted HTTP Referrers” should include the domain name used by the hosting wordpress site or left blank to allow all referrers</li>
</ul>
</li>
</ul>
<p>If the required options for the usage of Google Timezone API are not met, the detection mechanism falls back to the default one.</p>
<h4>Post Timezone Detection</h4>
<ul>
<li>If the browser’s timezone id is not detected successfully, everything else behaves as if this plugin is not installed.</li>
<li>If the browser’s timezone id is detected, the following actions take place
<ul>
<li>A cookie will be set in the browser, based on the cookie options specified on the plugin options page</li>
<li>If a cookie already exists previously with the same id, no action is taken</li>
<li>If a cookie doesn’t already exist previously or exists with a different timezone id, then a <em>window.reload</em> is triggered to refresh the page so that the dates/times on the page are updated</li>
</ul>
</li>
</ul>
<h4>EventON Hook</h4>
<p>This plugin provides a feature to hook into the EventON plugin. When enabled, all EventON dates/times are updated to reflect the browser’s timezone.</p>
<h4>Shortcodes</h4>
<p>This plugin defines the below shortcodes</p>
<ol>
<li>[wp_user_timezone_id] => Returns the timezone id of the browser or <em>null</em> if not available.</li>
<li>[wp_user_timezone_offset] => Returns the timezone’s gmt offset in hours of the browser or <em>null</em> if not available.</li>
</ol>
<h4>Options</h4>
<p>This plugin defines the below options to retrieve the original timezone_string and gmt_offset defined at the site level</p>
<ol>
<li>get_option( ‘site_timezone_string’ ) => Returns the original timezone_string option for the site</li>
<li>get_option( ‘site_gmt_offset’ ) => Returns the original gmt_offset option for the site</li>
</ol>
<h4>Actions/Hooks</h4>
<p>This plugin defines the below filters/hooks</p>
<ol>
<li>apply_filters( ‘wp_user_timezone_id’, $tz_id ) => Allows you to override the timezone string determined by the plugin. This filter can be used to apply user’s timezone preference. If any plugin or wordpress core implements a feature to accept and store user’s preferred timezone, the ‘wp_user_timezone_id’ can be used to apply that timezone value to the front-end. Reference: <a href="https://core.trac.wordpress.org/ticket/18146" rel="nofollow ugc">Add user-level timezone setting</a>).</li>
</ol>
<h4>Admin Backend Dates/Times</h4>
<p><strong>Important: The admin back-end is not modified by this plugin. All dates/times displayed in the back-end are still in the original timezone specified by the WordPress General Settings.</strong></p>


WP User Timezone

Magnificent

WP User Timezone displays the front-end dates & times in the browser's local timezone without actually modifying your database.

ezraverheijen

<p>This lightweight plugin can be used if the scheduled post feature is not working for you (missed scheduled post errors), and you host your site in a European country using CEST in the summer and CET during the winter.</p>


WP TimeZone

Takes care of publishing posts that missed their schedule, for CET/CEST time zones only.

WP User Timezone vs WP TimeZone