I tried the code that I wrote below (adopted from your code) and it works. Maybe you forgot to include jquery javascript for each language? As an example, I have included only three languages ββ(e.g. French). In addition, I have a change event to select an option in the language, rather than triggering onSelect.
I also tried your version of including it in one function, and this works, except that since it is optional, you must select the date first before it starts working, and then the language after that.
The first version (it works in one function, but a problem that does not appear in the language until a date is selected):
<html><head><title>Test1</title> <script type="text/javascript" src="jquery-1.7.2.min.js"></script> <link type="text/css" href="css/ui-lightness/jquery-ui-1.8.18.custom.css" rel="Stylesheet" /> <script type="text/javascript" src="js/jquery-ui-1.8.18.custom.min.js"></script> <script type="text/javascript" src="jquery.ui.datepicker-fr.js"></script> <script type="text/javascript" src="jquery.ui.datepicker-ar.js"></script> <script type="text/javascript" src="jquery.ui.datepicker-af.js"></script> <script type="text/javascript" src="jquery.ui.datepicker-en-GB.js"></script> </head><body> <script type="text/javascript"> $(function() { $.datepicker.setDefaults( $.datepicker.regional[ "" ] ); $( "#from" ).datepicker({ defaultDate: "+4w", changeMonth: true, numberOfMonths: 3, showButtonPanel: true, showOn: "button", minDate:"+1d", dateFormat:"yy/mm/dd", showAnim:"bounce", onSelect: function( selectedDate ) { $( "#from" ).datepicker( $.datepicker.regional[ "en-GB" ] ); $( "#locale" ).change(function() { $( "#from" ).datepicker( "option", $.datepicker.regional[ $( this ).val() ] ); }); } }); }); </script> <p>Date: <input type="text" id="from"/> <select id="locale"> <option value="af">Afrikaans</option> <option value="sq">Albanian (Gjuha shqipe)</option> <option value="ar-DZ">Algerian Arabic</option> <option value="ar">Arabic (‫(لعربي</option> <option value="hy">Armenian (Հայերեն)</option> <option value="az">Azerbaijani (Azərbaycan dili)</option> <option value="eu">Basque (Euskara)</option> <option value="bs">Bosnian (Bosanski)</option> <option value="bg">Bulgarian (български език)</option> <option value="ca">Catalan (Català)</option> <option value="zh-HK">Chinese Hong Kong (繁體中文)</option> <option value="zh-CN">Chinese Simplified (简体中文)</option> <option value="zh-TW">Chinese Traditional (繁體中文)</option> <option value="hr">Croatian (Hrvatski jezik)</option> <option value="cs">Czech (čeština)</option> <option value="da">Danish (Dansk)</option> <option value="nl-BE">Dutch (Belgium)</option> <option value="nl">Dutch (Nederlands)</option> <option value="en-AU">English/Australia</option> <option value="en-NZ">English/New Zealand</option> <option value="en-GB">English/UK</option> <option value="eo">Esperanto</option> <option value="et">Estonian (eesti keel)</option> <option value="fo">Faroese (føroyskt)</option> <option value="fa">Farsi/Persian (‫(فارسی</option> <option value="fi">Finnish (suomi)</option> <option value="fr" selected="selected">French (Français)</option> <option value="fr-CH">French/Swiss (Français de Suisse)</option> <option value="gl">Galician</option> <option value="ge">Georgian</option> <option value="de">German (Deutsch)</option> <option value="el">Greek (Ελληνικά)</option> <option value="he">Hebrew (‫(עברית</option> <option value="hi">Hindi (हिंदी)</option> <option value="hu">Hungarian (Magyar)</option> <option value="is">Icelandic (Õslenska)</option> <option value="id">Indonesian (Bahasa Indonesia)</option> <option value="it">Italian (Italiano)</option> <option value="ja">Japanese (日本語)</option> <option value="kk">Kazakhstan (Kazakh)</option> <option value="km">Khmer</option> <option value="ko">Korean (한국어)</option> <option value="lv">Latvian (Latvieöu Valoda)</option> <option value="lt">Lithuanian (lietuviu kalba)</option> <option value="lb">Luxembourgish</option> <option value="mk">Macedonian</option> <option value="ml">Malayalam</option> <option value="ms">Malaysian (Bahasa Malaysia)</option> <option value="no">Norwegian (Norsk)</option> <option value="pl">Polish (Polski)</option> <option value="pt">Portuguese (Português)</option> <option value="pt-BR">Portuguese/Brazilian (Português)</option> <option value="rm">Rhaeto-Romanic (Romansh)</option> <option value="ro">Romanian (Română)</option> <option value="ru">Russian (Русский)</option> <option value="sr">Serbian (српски језик)</option> <option value="sr-SR">Serbian (srpski jezik)</option> <option value="sk">Slovak (Slovencina)</option> <option value="sl">Slovenian (Slovenski Jezik)</option> <option value="es">Spanish (Español)</option> <option value="sv">Swedish (Svenska)</option> <option value="ta">Tamil (தமிழ்)</option> <option value="th">Thai (ภาษาไทย)</option> <option value="tj">Tajikistan</option> <option value="tr">Turkish (Türkçe)</option> <option value="uk">Ukranian (Українська)</option> <option value="vi">Vietnamese (Tiếng Việt)</option> <option value="cy-GB">Welsh/UK (Cymraeg)</option> </select></p> </body></html>
The second version (not in one function, also works, it seems to work better for me, because you do not need to select a date for its language change):
<html><head><title>Test1</title> <script type="text/javascript" src="jquery-1.7.2.min.js"></script> <link type="text/css" href="css/ui-lightness/jquery-ui-1.8.18.custom.css" rel="Stylesheet" /> <script type="text/javascript" src="js/jquery-ui-1.8.18.custom.min.js"></script> <script type="text/javascript" src="jquery.ui.datepicker-fr.js"></script> <script type="text/javascript" src="jquery.ui.datepicker-ar.js"></script> <script type="text/javascript" src="jquery.ui.datepicker-af.js"></script> </head><body> <script type="text/javascript"> $(function() { $.datepicker.setDefaults( $.datepicker.regional[ "" ] ); $( "#from" ).datepicker({ defaultDate: "+4w", changeMonth: true, numberOfMonths: 3, showButtonPanel: true, showOn: "button", minDate:"+1d", dateFormat:"yy/mm/dd", showAnim:"bounce" }); $( "#from" ).datepicker( $.datepicker.regional[ "en-GB" ] ); $( "#locale" ).change(function() { $( "#from" ).datepicker( "option", $.datepicker.regional[ $( this ).val() ] ); }); }); </script> <p>Date: <input type="text" id="from"/> <select id="locale"> <option value="af">Afrikaans</option> <option value="sq">Albanian (Gjuha shqipe)</option> <option value="ar-DZ">Algerian Arabic</option> <option value="ar">Arabic (‫(لعربي</option> <option value="hy">Armenian (Հայերեն)</option> <option value="az">Azerbaijani (Azərbaycan dili)</option> <option value="eu">Basque (Euskara)</option> <option value="bs">Bosnian (Bosanski)</option> <option value="bg">Bulgarian (български език)</option> <option value="ca">Catalan (Català)</option> <option value="zh-HK">Chinese Hong Kong (繁體中文)</option> <option value="zh-CN">Chinese Simplified (简体中文)</option> <option value="zh-TW">Chinese Traditional (繁體中文)</option> <option value="hr">Croatian (Hrvatski jezik)</option> <option value="cs">Czech (čeština)</option> <option value="da">Danish (Dansk)</option> <option value="nl-BE">Dutch (Belgium)</option> <option value="nl">Dutch (Nederlands)</option> <option value="en-AU">English/Australia</option> <option value="en-NZ">English/New Zealand</option> <option value="en-GB">English/UK</option> <option value="eo">Esperanto</option> <option value="et">Estonian (eesti keel)</option> <option value="fo">Faroese (føroyskt)</option> <option value="fa">Farsi/Persian (‫(فارسی</option> <option value="fi">Finnish (suomi)</option> <option value="fr" selected="selected">French (Français)</option> <option value="fr-CH">French/Swiss (Français de Suisse)</option> <option value="gl">Galician</option> <option value="ge">Georgian</option> <option value="de">German (Deutsch)</option> <option value="el">Greek (Ελληνικά)</option> <option value="he">Hebrew (‫(עברית</option> <option value="hi">Hindi (हिंदी)</option> <option value="hu">Hungarian (Magyar)</option> <option value="is">Icelandic (Õslenska)</option> <option value="id">Indonesian (Bahasa Indonesia)</option> <option value="it">Italian (Italiano)</option> <option value="ja">Japanese (日本語)</option> <option value="kk">Kazakhstan (Kazakh)</option> <option value="km">Khmer</option> <option value="ko">Korean (한국어)</option> <option value="lv">Latvian (Latvieöu Valoda)</option> <option value="lt">Lithuanian (lietuviu kalba)</option> <option value="lb">Luxembourgish</option> <option value="mk">Macedonian</option> <option value="ml">Malayalam</option> <option value="ms">Malaysian (Bahasa Malaysia)</option> <option value="no">Norwegian (Norsk)</option> <option value="pl">Polish (Polski)</option> <option value="pt">Portuguese (Português)</option> <option value="pt-BR">Portuguese/Brazilian (Português)</option> <option value="rm">Rhaeto-Romanic (Romansh)</option> <option value="ro">Romanian (Română)</option> <option value="ru">Russian (Русский)</option> <option value="sr">Serbian (српски језик)</option> <option value="sr-SR">Serbian (srpski jezik)</option> <option value="sk">Slovak (Slovencina)</option> <option value="sl">Slovenian (Slovenski Jezik)</option> <option value="es">Spanish (Español)</option> <option value="sv">Swedish (Svenska)</option> <option value="ta">Tamil (தமிழ்)</option> <option value="th">Thai (ภาษาไทย)</option> <option value="tj">Tajikistan</option> <option value="tr">Turkish (Türkçe)</option> <option value="uk">Ukranian (Українська)</option> <option value="vi">Vietnamese (Tiếng Việt)</option> <option value="cy-GB">Welsh/UK (Cymraeg)</option> </select></p> </body></html>
Literature:
http://jqueryui.com/demos/datepicker/#localization
http://jquery-ui.googlecode.com/svn/trunk/ui/i18n/