Ignore timezone offset while converting date - javascript

Question

I have a WCF REST service that returns date in below format:

/Date(1401993000000+0530)/

The value of this date on the server is

6/6/2014 12:00:00 AM

I want to parse this in my javascript code in UTC value.

I tried manually removing the "+0530" string and parsing it to date but it gives "Invalid Date".

I also tried adding the timezone offset as per this post but it gives incorrect value.

How can I parse this?

Answer 1

This format is commonly referred to as an "ASP.NET JSON Date" - because it first emerged from the JavaScriptSerializer and DataContractJsonSerializer classes used in ASP.NET and other parts of .NET. However, it was heavily criticized , and ultimately deprecated in favor of the standard ISO 8601 format, which is the default in the Json.Net library used in most modern .NET code. You'll still see it in WCF, and in older versions of ASP.NET MVC.

This format has two main variations:

• /Date(1401993000000)/ - A timestamp alone
• /Date(1401993000000+0530)/ - A timestamp with an offset

You will occasionally see the forward slashes escaped with backslashes, as in \\/Date(1401993000000)\\/ , depending on how it was generated. This should be tolerated by parsers, but should not be depended upon.

In both formats shown, the timestamp portion is intended to represent the number of milliseconds since the Unix Epoch, which is 1970-01-01 00:00:00.000 UTC.

I say "intended", because it is possible in .NET to have a DateTime with DateTimeKind.Unspecified , which can't possibly be mapped back to UTC. In this case, the serializer will act as if it had DateTimeKind.Local . The output will then reflect the value adjusted to UTC in the computer's local time zone, along with the computer's UTC offset for that point in time. Ideally, you should not rely on this behavior, as you will get different results from computers in different time zones.

When an offset is present in the output string, it is in +HHmm / -HHmm format, with positive values falling East of GMT - the same direction as the ISO 8601 standard. However, unlike ISO 8601, the value portion is not adjusted for that offset. It remains UTC-based.

In other words:

• /Date(1401993000000)/ = 2014-06-05T18:30:00Z
• /Date(1401993000000+0530)/ = 2014-06-05T18:30:00Z + +0530 = 2014-06-06T00:00:00+05:30

Because of this, the offset portion is extraneous when using this value to create a JavaScript Date object - since a Date object wraps a timestamp in UTC, and has no provision for retaining a provided offset.

You can certainly break out the string into its parts and use them yourself, but instead consider using Moment.js for parsing this string. It understands the format natively, and can give you back an object that retains knowledge of the offset.

var m = moment.parseZone("/Date(1401993000000+0530)/");

m.format() // "2014-06-06T00:00:00+05:30"

If you were looking for a Date object, you can certainly call m.toDate() . The resulting Date object will have the same UTC timestamp, but due to how the Date object works, any local-time functions will only use the offset of the host environment.

In other words, with output of a Date object, the +0530 part of your input becomes useless. You might have well have parsed /Date(1401993000000)/ .

Answer 2

You can use Moment JS, one of the better ways to play with datetime in JavaSCript. Lot of functions

https://momentjs.com/timezone/

See the edited message, without momentjs:

  var data = [ {"id":1,"start":"/Date(1401993000000+0530)/"} ]; var myDate = new Date(data[0].start.match(/\\d+/)[0] * 1); myDate = new Date(myDate.getTime() + myDate.getTimezoneOffset() * 60 * 1000); alert(myDate);