What is the best way to handle time zones with Javascript -

i have authenticated user given time zone, e.g. "berlin, gmt+1". sake of question let's have in global scope:

var timezone = "berlin"; var gmtdistance = 1; 

what best solution have date-related js behave accordingly, meaning if create new date object take timezone account.

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i thought it'd pretty straightforward, don't seem find perfect way on google/so. privilege answer doesn't need external library.

my preference store dates on server side using utc time, , when handling data coming via ajax calls, create global handler parsing.

the following example allows use:

app.ajax({     url: '/my/post/url',     data: {         myproperty: 'myvalue'     },     success: function (data, status, xhr) {         // stuff here...     },     error: function (xhr, settings, error) {         // stuff here...     } }); 

but, pre-parses returned values in "success" function's "data" element fixing dates utc time local timezone. aware - after doing this, if further process data, need un-fix before sending server, or you'll posting offset.

var app = window.app = $.extend(true, {}, app, {     // creating namespace app safe across multiple files.     ajax: function (options) {         var defaultsettings = {             type: 'post',             async: true         };          // capture settings.         var settings = $.extend(true, {}, defaultsettings, options);          // install our general handlers;         if (settings.success) {             settings.success = function (data, textstatus, jqxhr) {                 app.onpostsuccess(data, textstatus, jqxhr, options.success);             }         } else              settings.success = app.onpostsuccess;          if (settings.error) {             settings.error = function (jqxhr, ajaxsettings, thrownerror) {                 app.onposterror(event, jqxhr, ajaxsettings, thrownerror, options.error);             }         } else             settings.error = app.onposterror;          $.ajax(settings);     },     onpostsuccess: function (data, textstatus, jqxhr, fn_after) {         // generalized success handling here.          // fix dates.         var fixeddata = app.fixdate(data);          // call other handler that's been specified.         if (typeof fn_after === 'function')             fn_after(fixeddata, textstatus, jqxhr);     },     onposterror: function (jqxhr, ajaxsettings, thrownerror, fn_after) {         // generalized error handling here.          // call other handler that's been specified.         if (typeof fn_after === 'function')             fn_after(jqxhr, ajaxsettings, thrownerror);     },     fixdate: function (obj) {         var fixed = obj;          if (typeof obj == 'string' && obj.indexof('\/date(') == 0) {             // microsoft date "/date(12345678)/" - convert real date.             fixed = new date(parseint(fixed.substr(6, fixed.length - 8), 10));         }          if (typeof fixed === 'object') {             if (fixed.gettimezoneoffset) {                 // if value date, apply timezone correction.                 var = new date();                 var offset = now.gettimezoneoffset(); // # of minutes gmt.                 fixed = new date(fixed.gettime() + offset * 60000);                 // updates value based on offset.             } else {                 // otherwise, update each of properties.                 // fixes objects dates properties, recursively.                 $.each(fixed, function (index, value) {                     fixed[index] = app.fixdate(value);                 });             }         }          return fixed;     } }); 

all of set-up this. if handle things dates within onpostsuccess, can ensure in right format - , in right timezone.

whether or not use above ajax methods, can use fixdate method follows:

var myobj = {      mydate: "\/date(12345678)\/" };  console.log('before: ', myobj.mydate); myobj = app.fixdate(myobj); console.log('after: ', myobj.mydate); 

to see example in action, check out following jsfiddle:

http://jsfiddle.net/troyalford/tbnvv/

note: includes ajax bits - aren't used in example - there completeness.