This is a simple gem which bundles jstimezonedetect and my own jquery plugin for it

NOTE: There is no dependency on jquery, so you can also use this to simply bundle jstimezonedetect.

In your Gemfile:

gem 'detect_timezone_rails'

Require detect_timezone and jquery.detect_timezone in your Javascript manifest (i.e. application.js)

//= require detect_timezone
//= require jquery.detect_timezone

Then some where else, wire it up using the plugin (remember to require jquery as well for the plugin)

$(document).ready(function(){
	$('#your_input_id').set_timezone(); 
});

If you are using the standard rails form helpers to generate a timezone select, you may pass the format option when calling set_timezone, to return only the city name:

$(document).ready(function(){
    $('#your_input_id').set_timezone({format: 'city'});
})

Requires Rails 3.1+.

Provided under the Do Whatever You Want With This Code License.