[jquery] How do I format a Microsoft JSON date?

I'm taking my first crack at Ajax with jQuery. I'm getting my data onto my page, but I'm having some trouble with the JSON data that is returned for Date data types. Basically, I'm getting a string back that looks like this:

/Date(1224043200000)/

From someone totally new to JSON - How do I format this to a short date format? Should this be handled somewhere in the jQuery code? I've tried the jQuery.UI.datepicker plugin using $.datepicker.formatDate() without any success.

FYI: Here's the solution I came up with using a combination of the answers here:

function getMismatch(id) {
  $.getJSON("Main.aspx?Callback=GetMismatch",
    { MismatchId: id },

    function (result) {
      $("#AuthMerchId").text(result.AuthorizationMerchantId);
      $("#SttlMerchId").text(result.SettlementMerchantId);
      $("#CreateDate").text(formatJSONDate(Date(result.AppendDts)));
      $("#ExpireDate").text(formatJSONDate(Date(result.ExpiresDts)));
      $("#LastUpdate").text(formatJSONDate(Date(result.LastUpdateDts)));
      $("#LastUpdatedBy").text(result.LastUpdateNt);
      $("#ProcessIn").text(result.ProcessIn);
    }
  );

  return false;
}

function formatJSONDate(jsonDate) {
  var newDate = dateFormat(jsonDate, "mm/dd/yyyy");
  return newDate;
}

This solution got my object from the callback method and displayed the dates on the page properly using the date format library.

If you are using Kotlin then this will solve your problem.

val dataString = "/Date(1586583441106)/"
val date = Date(Long.parseLong(dataString.substring(6, dataString.length - 2)))

It's easy to convert JSON date to a JavaScript Date:

var s = Response.StartDate;     
s = s.replace('/Date(', '');

s = s.replace(')/', '');

var expDate = new Date(parseInt(s));

You can use this to get a date from JSON:

var date = eval(jsonDate.replace(/\/Date\((\d+)\)\//gi, "new Date($1)"));

And then you can use a JavaScript Date Format script (1.2 KB when minified and gzipped) to display it as you want.

Another regex example you can try using:

var mydate = json.date
var date = new Date(parseInt(mydate.replace(/\/Date\((-?\d+)\)\//, '$1');
mydate = date.getMonth() + 1 + '/' + date.getDate() + '/' + date.getFullYear();

date.getMonth() returns an integer 0 - 11 so we must add 1 to get the right month number wise

Your JSON should probably be returning an object of some sort (well, a string representation thereof).

"{ myDate : Date(1224043200000) }"

Using jQuery, you can access your data object this way:

$.get(
    "myJSONFile.php",
    function (data) {
        // data.myDate will be a date object.

        // to show in a short date format (eg: dd/mm/yyyy)
        alert (
            data.myDate.getDate() + "/"
            + (data.myDate.getMonth() + 1) + "/"
            + data.myDate.getFullYear()
        ); // alerts: "15/10/2008"
    }
);

If you say in JavaScript,

var thedate = new Date(1224043200000);
alert(thedate);

you will see that it's the correct date, and you can use that anywhere in JavaScript code with any framework.

I use this simple function for getting date from Microsoft JSON Date

function getDateValue(dateVal) {
    return new Date(parseInt(dateVal.replace(/\D+/g, '')));
};

replace(/\D+/g, '') will remove all characters other than numbers

parseInt will convert the string to number

Usage

$scope.ReturnDate = getDateValue(result.JSONDateVariable)

Don't repeat yourself - automate date conversion using $.parseJSON()

Answers to your post provide manual date conversion to JavaScript dates. I've extended jQuery's $.parseJSON() just a little bit, so it's able to automatically parse dates when you instruct it to. It processes ASP.NET formatted dates (/Date(12348721342)/) as well as ISO formatted dates (2010-01-01T12.34.56.789Z) that are supported by native JSON functions in browsers (and libraries like json2.js).

Anyway. If you don't want to repeat your date conversion code over and over again I suggest you read this blog post and get the code that will make your life a little easier.

What if .NET returns...

return DateTime.Now.ToString("u"); //"2013-09-17 15:18:53Z"

And then in JavaScript...

var x = new Date("2013-09-17 15:18:53Z");

var newDate = dateFormat(jsonDate, "mm/dd/yyyy"); 

Is there another option without using the jQuery library?

There is no built in date type in JSON. This looks like the number of seconds / milliseconds from some epoch. If you know the epoch you can create the date by adding on the right amount of time.

For those using Newtonsoft Json.NET, read up on how to do it via Native JSON in IE8, Firefox 3.5 plus Json.NET.

Also the documentation on changing the format of dates written by Json.NET is useful: Serializing Dates with Json.NET

For those that are too lazy, here are the quick steps. As JSON has a loose DateTime implementation, you need to use the IsoDateTimeConverter(). Note that since Json.NET 4.5 the default date format is ISO so the code below isn't needed.

string jsonText = JsonConvert.SerializeObject(p, new IsoDateTimeConverter());

The JSON will come through as

"fieldName": "2009-04-12T20:44:55"

Finally, some JavaScript to convert the ISO date to a JavaScript date:

function isoDateReviver(value) {
  if (typeof value === 'string') {
    var a = /^(\d{4})-(\d{2})-(\d{2})T(\d{2}):(\d{2}):(\d{2}(?:\.\d*)?)(?:([\+-])(\d{2})\:(\d{2}))?Z?$/.exec(value);
      if (a) {
        var utcMilliseconds = Date.UTC(+a[1], +a[2] - 1, +a[3], +a[4], +a[5], +a[6]);
        return new Date(utcMilliseconds);
      }
  }
  return value;
}

I used it like this

$("<span />").text(isoDateReviver(item.fieldName).toLocaleString()).appendTo("#" + divName);

You can use this to get a date from JSON:

var date = eval(jsonDate.replace(/\/Date\((\d+)\)\//gi, "new Date($1)"));

And then you can use a JavaScript Date Format script (1.2 KB when minified and gzipped) to display it as you want.

The original example:

/Date(1224043200000)/  

does not reflect the formatting used by WCF when sending dates via WCF REST using the built-in JSON serialization. (at least on .NET 3.5, SP1)

I found the answer here helpful, but a slight edit to the regex is required, as it appears that the timezone GMT offset is being appended onto the number returned (since 1970) in WCF JSON.

In a WCF service I have:

[OperationContract]
[WebInvoke(
    RequestFormat = WebMessageFormat.Json,
    ResponseFormat = WebMessageFormat.Json,
    BodyStyle = WebMessageBodyStyle.WrappedRequest
    )]
ApptVisitLinkInfo GetCurrentLinkInfo( int appointmentsId );

ApptVisitLinkInfo is defined simply:

public class ApptVisitLinkInfo {
    string Field1 { get; set; }
    DateTime Field2 { get; set; }
    ...
}

When "Field2" is returned as Json from the service the value is:

/Date(1224043200000-0600)/

Notice the timezone offset included as part of the value.

The modified regex:

/\/Date\((.*?)\)\//gi

It's slightly more eager and grabs everything between the parens, not just the first number. The resulting time sinze 1970, plus timezone offset can all be fed into the eval to get a date object.

The resulting line of JavaScript for the replace is:

replace(/\/Date\((.*?)\)\//gi, "new Date($1)");

Just to add another approach here, the "ticks approach" that WCF takes is prone to problems with timezones if you're not extremely careful such as described here and in other places. So I'm now using the ISO 8601 format that both .NET & JavaScript duly support that includes timezone offsets. Below are the details:

In WCF/.NET:

Where CreationDate is a System.DateTime; ToString("o") is using .NET's Round-trip format specifier that generates an ISO 8601-compliant date string

new MyInfo {
    CreationDate = r.CreationDate.ToString("o"),
};

In JavaScript

Just after retrieving the JSON I go fixup the dates to be JavaSript Date objects using the Date constructor which accepts an ISO 8601 date string...

$.getJSON(
    "MyRestService.svc/myinfo",
    function (data) {
        $.each(data.myinfos, function (r) {
            this.CreatedOn = new Date(this.CreationDate);
        });
        // Now each myinfo object in the myinfos collection has a CreatedOn field that is a real JavaScript date (with timezone intact).
       alert(data.myinfos[0].CreationDate.toLocaleString());
    }
)

Once you have a JavaScript date you can use all the convenient and reliable Date methods like toDateString, toLocaleString, etc.

Add the jQuery UI plugin in your page:

function DateFormate(dateConvert) {
    return $.datepicker.formatDate("dd/MM/yyyy", eval('new ' + dateConvert.slice(1, -1)));
};

Mootools solution:

new Date(Date(result.AppendDts)).format('%x')

Requires mootools-more. Tested using mootools-1.2.3.1-more on Firefox 3.6.3 and IE 7.0.5730.13

I use this simple function for getting date from Microsoft JSON Date

function getDateValue(dateVal) {
    return new Date(parseInt(dateVal.replace(/\D+/g, '')));
};

replace(/\D+/g, '') will remove all characters other than numbers

parseInt will convert the string to number

Usage

$scope.ReturnDate = getDateValue(result.JSONDateVariable)

The simplest way I can suggest is using regex on JS as:

//Only use [0] if you are sure that the string matches the pattern
//Otherwise, verify if 'match' returns something
"/Date(1512488018202)/".match(/\d+/)[0] 

Using the jQuery UI datepicker - really only makes sense if you're already including jQuery UI:

$.datepicker.formatDate('MM d, yy', new Date(parseInt('/Date(1224043200000)/'.substr(6)))); 

output:

October 15, 2008

I get the date like this:

"/Date(1276290000000+0300)/"

In some examples the date is in slightly different formats:

"/Date(12762900000000300)/"
"Date(1276290000000-0300)"

etc.

So I came up with the following RegExp:

/\/+Date\(([\d+]+)\)\/+/

and the final code is:

var myDate = new Date(parseInt(jsonWcfDate.replace(/\/+Date\(([\d+-]+)\)\/+/, '$1')));

Hope it helps.

Update: I found this link from Microsoft: How do I Serialize Dates with JSON?

This seems like the one we are all looking for.

The original example:

/Date(1224043200000)/  

does not reflect the formatting used by WCF when sending dates via WCF REST using the built-in JSON serialization. (at least on .NET 3.5, SP1)

I found the answer here helpful, but a slight edit to the regex is required, as it appears that the timezone GMT offset is being appended onto the number returned (since 1970) in WCF JSON.

In a WCF service I have:

[OperationContract]
[WebInvoke(
    RequestFormat = WebMessageFormat.Json,
    ResponseFormat = WebMessageFormat.Json,
    BodyStyle = WebMessageBodyStyle.WrappedRequest
    )]
ApptVisitLinkInfo GetCurrentLinkInfo( int appointmentsId );

ApptVisitLinkInfo is defined simply:

public class ApptVisitLinkInfo {
    string Field1 { get; set; }
    DateTime Field2 { get; set; }
    ...
}

When "Field2" is returned as Json from the service the value is:

/Date(1224043200000-0600)/

Notice the timezone offset included as part of the value.

The modified regex:

/\/Date\((.*?)\)\//gi

It's slightly more eager and grabs everything between the parens, not just the first number. The resulting time sinze 1970, plus timezone offset can all be fed into the eval to get a date object.

The resulting line of JavaScript for the replace is:

replace(/\/Date\((.*?)\)\//gi, "new Date($1)");

As a side note, KendoUI supports to convert Microsoft JSON date. So, If your project has the reference to "KendoUI", you may simply use

var newDate = kendo.parseDate(jsonDate);

If you say in JavaScript,

var thedate = new Date(1224043200000);
alert(thedate);

you will see that it's the correct date, and you can use that anywhere in JavaScript code with any framework.

Your JSON should probably be returning an object of some sort (well, a string representation thereof).

"{ myDate : Date(1224043200000) }"

Using jQuery, you can access your data object this way:

$.get(
    "myJSONFile.php",
    function (data) {
        // data.myDate will be a date object.

        // to show in a short date format (eg: dd/mm/yyyy)
        alert (
            data.myDate.getDate() + "/"
            + (data.myDate.getMonth() + 1) + "/"
            + data.myDate.getFullYear()
        ); // alerts: "15/10/2008"
    }
);

It's easy to convert JSON date to a JavaScript Date:

var s = Response.StartDate;     
s = s.replace('/Date(', '');

s = s.replace(')/', '');

var expDate = new Date(parseInt(s));

There is no built in date type in JSON. This looks like the number of seconds / milliseconds from some epoch. If you know the epoch you can create the date by adding on the right amount of time.

Below is a pretty simple solution for parsing JSON dates. Use the below functions as per your requirement. You just need to pass the JSON format Date fetched as a parameter to the functions below:

function JSONDate(dateStr) {
    var m, day;
    jsonDate = dateStr;
    var d = new Date(parseInt(jsonDate.substr(6)));
    m = d.getMonth() + 1;
    if (m < 10)
        m = '0' + m
    if (d.getDate() < 10)
        day = '0' + d.getDate()
    else
        day = d.getDate();
    return (m + '/' + day + '/' + d.getFullYear())
}

function JSONDateWithTime(dateStr) {
    jsonDate = dateStr;
    var d = new Date(parseInt(jsonDate.substr(6)));
    var m, day;
    m = d.getMonth() + 1;
    if (m < 10)
        m = '0' + m
    if (d.getDate() < 10)
        day = '0' + d.getDate()
    else
        day = d.getDate();
    var formattedDate = m + "/" + day + "/" + d.getFullYear();
    var hours = (d.getHours() < 10) ? "0" + d.getHours() : d.getHours();
    var minutes = (d.getMinutes() < 10) ? "0" + d.getMinutes() : d.getMinutes();
    var formattedTime = hours + ":" + minutes + ":" + d.getSeconds();
    formattedDate = formattedDate + " " + formattedTime;
    return formattedDate;
}

var obj = eval('(' + "{Date: \/Date(1278903921551)\/}".replace(/\/Date\((\d+)\)\//gi, "new Date($1)") + ')');
var dateValue = obj["Date"];

Try this...

function formatJSONDate(jsonDate) {
            var date = jsonDate;
            var parsedDate = new Date(parseInt(date.toString().substring(6)));
            var newDate = new Date(parsedDate);
            var getMonth = newDate.getMonth() + 1;
            var getDay = newDate.getDay();
            var getYear = newDate.getFullYear(); 

            var standardDate = (getMonth<10 ? '0' : '') + getMonth + '/' + (getDay<10 ? '0' : '') + getDay + '/' + getYear;
            return standardDate;
        }

getYear() returns the year - 1900, This has been deprecated for a while now, it's best to use getFullYear()

This may can also help you.

 function ToJavaScriptDate(value) { //To Parse Date from the Returned Parsed Date
        var pattern = /Date\(([^)]+)\)/;
        var results = pattern.exec(value);
        var dt = new Date(parseFloat(results[1]));
        return (dt.getMonth() + 1) + "/" + dt.getDate() + "/" + dt.getFullYear();
    }

A late post, but for those who searched this post.

Imagine this:

    [Authorize(Roles = "Administrator")]
    [Authorize(Roles = "Director")]
    [Authorize(Roles = "Human Resources")]
    [HttpGet]
    public ActionResult GetUserData(string UserIdGuidKey)
    {
        if (UserIdGuidKey!= null)
        {
            var guidUserId = new Guid(UserIdGuidKey);
            var memuser = Membership.GetUser(guidUserId);
            var profileuser = Profile.GetUserProfile(memuser.UserName);
            var list = new {
                              UserName = memuser.UserName,
                              Email = memuser.Email ,
                              IsApproved = memuser.IsApproved.ToString() ,
                              IsLockedOut = memuser.IsLockedOut.ToString() ,
                              LastLockoutDate = memuser.LastLockoutDate.ToString() ,
                              CreationDate = memuser.CreationDate.ToString() ,
                              LastLoginDate = memuser.LastLoginDate.ToString() ,
                              LastActivityDate = memuser.LastActivityDate.ToString() ,
                              LastPasswordChangedDate = memuser.LastPasswordChangedDate.ToString() ,
                              IsOnline = memuser.IsOnline.ToString() ,
                              FirstName = profileuser.FirstName ,
                              LastName = profileuser.LastName ,
                              NickName = profileuser.NickName ,
                              BirthDate = profileuser.BirthDate.ToString() ,
            };
            return Json(list, JsonRequestBehavior.AllowGet);
        }
        return Redirect("Index");
    }

As you can see, I'm utilizing C# 3.0's feature for creating the "Auto" Generics. It's a bit lazy, but I like it and it works. Just a note: Profile is a custom class I've created for my web application project.

Another regex example you can try using:

var mydate = json.date
var date = new Date(parseInt(mydate.replace(/\/Date\((-?\d+)\)\//, '$1');
mydate = date.getMonth() + 1 + '/' + date.getDate() + '/' + date.getFullYear();

date.getMonth() returns an integer 0 - 11 so we must add 1 to get the right month number wise

Check up the date ISO standard; kind of like this:

yyyy.MM.ddThh:mm

It becomes 2008.11.20T22:18.

If you say in JavaScript,

var thedate = new Date(1224043200000);
alert(thedate);

you will see that it's the correct date, and you can use that anywhere in JavaScript code with any framework.

Check up the date ISO standard; kind of like this:

yyyy.MM.ddThh:mm

It becomes 2008.11.20T22:18.

Everyone of these answers has one thing in common: they all store dates as a single value (usually a string).

Another option is to take advantage of the inherent structure of JSON, and represent a date as list of numbers:

{ "name":"Nick",
  "birthdate":[1968,6,9] }

Of course, you would have to make sure both ends of the conversation agree on the format (year, month, day), and which fields are meant to be dates,... but it has the advantage of completely avoiding the issue of date-to-string conversion. It's all numbers -- no strings at all. Also, using the order: year, month, day also allows proper sorting by date.

Just thinking outside the box here -- a JSON date doesn't have to be stored as a string.

Another bonus to doing it this way is that you can easily (and efficiently) select all records for a given year or month by leveraging the way CouchDB handles queries on array values.

For those using Newtonsoft Json.NET, read up on how to do it via Native JSON in IE8, Firefox 3.5 plus Json.NET.

Also the documentation on changing the format of dates written by Json.NET is useful: Serializing Dates with Json.NET

For those that are too lazy, here are the quick steps. As JSON has a loose DateTime implementation, you need to use the IsoDateTimeConverter(). Note that since Json.NET 4.5 the default date format is ISO so the code below isn't needed.

string jsonText = JsonConvert.SerializeObject(p, new IsoDateTimeConverter());

The JSON will come through as

"fieldName": "2009-04-12T20:44:55"

Finally, some JavaScript to convert the ISO date to a JavaScript date:

function isoDateReviver(value) {
  if (typeof value === 'string') {
    var a = /^(\d{4})-(\d{2})-(\d{2})T(\d{2}):(\d{2}):(\d{2}(?:\.\d*)?)(?:([\+-])(\d{2})\:(\d{2}))?Z?$/.exec(value);
      if (a) {
        var utcMilliseconds = Date.UTC(+a[1], +a[2] - 1, +a[3], +a[4], +a[5], +a[6]);
        return new Date(utcMilliseconds);
      }
  }
  return value;
}

I used it like this

$("<span />").text(isoDateReviver(item.fieldName).toLocaleString()).appendTo("#" + divName);

The simplest way I can suggest is using regex on JS as:

//Only use [0] if you are sure that the string matches the pattern
//Otherwise, verify if 'match' returns something
"/Date(1512488018202)/".match(/\d+/)[0] 

In jQuery 1.5, as long as you have json2.js to cover for older browsers, you can deserialize all dates coming from Ajax as follows:

(function () {
    var DATE_START = "/Date(";
    var DATE_START_LENGTH = DATE_START.length;

    function isDateString(x) {
        return typeof x === "string" && x.startsWith(DATE_START);
    }

    function deserializeDateString(dateString) {
        var dateOffsetByLocalTime = new Date(parseInt(dateString.substr(DATE_START_LENGTH)));
        var utcDate = new Date(dateOffsetByLocalTime.getTime() - dateOffsetByLocalTime.getTimezoneOffset() * 60 * 1000);
        return utcDate;
    }

    function convertJSONDates(key, value) {
      if (isDateString(value)) {
        return deserializeDateString(value);
      }
      return value;
    }

    window.jQuery.ajaxSetup({
      converters: {
        "text json": function(data) {
          return window.JSON.parse(data, convertJSONDates);
        }
      }
    });
}());

I included logic that assumes you send all dates from the server as UTC (which you should); the consumer then gets a JavaScript Date object that has the proper ticks value to reflect this. That is, calling getUTCHours(), etc. on the date will return the same value as it did on the server, and calling getHours() will return the value in the user's local timezone as determined by their browser.

This does not take into account WCF format with timezone offsets, though that would be relatively easy to add.

Don't repeat yourself - automate date conversion using $.parseJSON()

Answers to your post provide manual date conversion to JavaScript dates. I've extended jQuery's $.parseJSON() just a little bit, so it's able to automatically parse dates when you instruct it to. It processes ASP.NET formatted dates (/Date(12348721342)/) as well as ISO formatted dates (2010-01-01T12.34.56.789Z) that are supported by native JSON functions in browsers (and libraries like json2.js).

Anyway. If you don't want to repeat your date conversion code over and over again I suggest you read this blog post and get the code that will make your life a little easier.

Mootools solution:

new Date(Date(result.AppendDts)).format('%x')

Requires mootools-more. Tested using mootools-1.2.3.1-more on Firefox 3.6.3 and IE 7.0.5730.13

I get the date like this:

"/Date(1276290000000+0300)/"

In some examples the date is in slightly different formats:

"/Date(12762900000000300)/"
"Date(1276290000000-0300)"

etc.

So I came up with the following RegExp:

/\/+Date\(([\d+]+)\)\/+/

and the final code is:

var myDate = new Date(parseInt(jsonWcfDate.replace(/\/+Date\(([\d+-]+)\)\/+/, '$1')));

Hope it helps.

Update: I found this link from Microsoft: How do I Serialize Dates with JSON?

This seems like the one we are all looking for.

Using the jQuery UI datepicker - really only makes sense if you're already including jQuery UI:

$.datepicker.formatDate('MM d, yy', new Date(parseInt('/Date(1224043200000)/'.substr(6)))); 

output:

October 15, 2008

Click here to check the Demo

JavaScript/jQuery

var = MyDate_String_Value = "/Date(1224043200000)/"
var value = new Date
            (
                 parseInt(MyDate_String_Value.replace(/(^.*\()|([+-].*$)/g, ''))
            );
var dat = value.getMonth() +
                         1 +
                       "/" +
           value.getDate() +
                       "/" +
       value.getFullYear();

Result - "10/15/2008"

Try this...

function formatJSONDate(jsonDate) {
            var date = jsonDate;
            var parsedDate = new Date(parseInt(date.toString().substring(6)));
            var newDate = new Date(parsedDate);
            var getMonth = newDate.getMonth() + 1;
            var getDay = newDate.getDay();
            var getYear = newDate.getFullYear(); 

            var standardDate = (getMonth<10 ? '0' : '') + getMonth + '/' + (getDay<10 ? '0' : '') + getDay + '/' + getYear;
            return standardDate;
        }

getYear() returns the year - 1900, This has been deprecated for a while now, it's best to use getFullYear()

This is frustrating. My solution was to parse out the "/ and /" from the value generated by ASP.NET's JavaScriptSerializer so that, though JSON may not have a date literal, it still gets interpreted by the browser as a date, which is what all I really want:{"myDate":Date(123456789)}

Custom JavaScriptConverter for DateTime?

I must emphasize the accuracy of Roy Tinker's comment. This is not legal JSON. It's a dirty, dirty hack on the server to remove the issue before it becomes a problem for JavaScript. It will choke a JSON parser. I used it for getting off the ground, but I do not use this any more. However, I still feel the best answer lies with changing how the server formats the date, for example, ISO as mentioned elsewhere.

Just to add another approach here, the "ticks approach" that WCF takes is prone to problems with timezones if you're not extremely careful such as described here and in other places. So I'm now using the ISO 8601 format that both .NET & JavaScript duly support that includes timezone offsets. Below are the details:

In WCF/.NET:

Where CreationDate is a System.DateTime; ToString("o") is using .NET's Round-trip format specifier that generates an ISO 8601-compliant date string

new MyInfo {
    CreationDate = r.CreationDate.ToString("o"),
};

In JavaScript

Just after retrieving the JSON I go fixup the dates to be JavaSript Date objects using the Date constructor which accepts an ISO 8601 date string...

$.getJSON(
    "MyRestService.svc/myinfo",
    function (data) {
        $.each(data.myinfos, function (r) {
            this.CreatedOn = new Date(this.CreationDate);
        });
        // Now each myinfo object in the myinfos collection has a CreatedOn field that is a real JavaScript date (with timezone intact).
       alert(data.myinfos[0].CreationDate.toLocaleString());
    }
)

Once you have a JavaScript date you can use all the convenient and reliable Date methods like toDateString, toLocaleString, etc.

You also can use the JavaScript library moment.js, which comes in handy when you plan do deal with different localized formats and perform other operations with dates values:

function getMismatch(id) {
    $.getJSON("Main.aspx?Callback=GetMismatch",
    { MismatchId: id },

    function (result) {
        $("#AuthMerchId").text(result.AuthorizationMerchantId);
        $("#SttlMerchId").text(result.SettlementMerchantId);
        $("#CreateDate").text(moment(result.AppendDts).format("L"));
        $("#ExpireDate").text(moment(result.ExpiresDts).format("L"));
        $("#LastUpdate").text(moment(result.LastUpdateDts).format("L"));
        $("#LastUpdatedBy").text(result.LastUpdateNt);
        $("#ProcessIn").text(result.ProcessIn);
    }
    );
    return false;
}

Setting up localization is as easy as adding configuration files (you get them at momentjs.com) to your project and configuring the language:

moment.lang('de');

I also had to search for a solution to this problem and eventually I came across moment.js which is a nice library that can parse this date format and many more.

var d = moment(yourdatestring)

It saved some headache for me so I thought I'd share it with you. :)
You can find some more info about it here: http://momentjs.com/

Posting in awesome thread:

var d = new Date(parseInt('/Date(1224043200000)/'.slice(6, -2)));
alert('' + (1 + d.getMonth()) + '/' + d.getDate() + '/' + d.getFullYear().toString().slice(-2));

Don't over-think this. Like we've done for decades, pass a numeric offset from the de-facto standard epoch of 1 Jan 1970 midnight GMT/UTC/&c in number of seconds (or milliseconds) since this epoch. JavaScript likes it, Java likes it, C likes it, and the Internet likes it.

I ended up adding the "characters into Panos's regular expression to get rid of the ones generated by the Microsoft serializer for when writing objects into an inline script:

So if you have a property in your C# code-behind that's something like

protected string JsonObject { get { return jsSerialiser.Serialize(_myObject); }}

And in your aspx you have

<script type="text/javascript">
    var myObject = '<%= JsonObject %>';
</script>

You'd get something like

var myObject = '{"StartDate":"\/Date(1255131630400)\/"}';

Notice the double quotes.

To get this into a form that eval will correctly deserialize, I used:

myObject = myObject.replace(/"\/Date\((\d+)\)\/"/g, 'new Date($1)');

I use Prototype and to use it I added

String.prototype.evalJSONWithDates = function() {
    var jsonWithDates = this.replace(/"\/Date\((\d+)\)\/"/g, 'new Date($1)');
    return jsonWithDates.evalJSON(true);
}

Below is a pretty simple solution for parsing JSON dates. Use the below functions as per your requirement. You just need to pass the JSON format Date fetched as a parameter to the functions below:

function JSONDate(dateStr) {
    var m, day;
    jsonDate = dateStr;
    var d = new Date(parseInt(jsonDate.substr(6)));
    m = d.getMonth() + 1;
    if (m < 10)
        m = '0' + m
    if (d.getDate() < 10)
        day = '0' + d.getDate()
    else
        day = d.getDate();
    return (m + '/' + day + '/' + d.getFullYear())
}

function JSONDateWithTime(dateStr) {
    jsonDate = dateStr;
    var d = new Date(parseInt(jsonDate.substr(6)));
    var m, day;
    m = d.getMonth() + 1;
    if (m < 10)
        m = '0' + m
    if (d.getDate() < 10)
        day = '0' + d.getDate()
    else
        day = d.getDate();
    var formattedDate = m + "/" + day + "/" + d.getFullYear();
    var hours = (d.getHours() < 10) ? "0" + d.getHours() : d.getHours();
    var minutes = (d.getMinutes() < 10) ? "0" + d.getMinutes() : d.getMinutes();
    var formattedTime = hours + ":" + minutes + ":" + d.getSeconds();
    formattedDate = formattedDate + " " + formattedTime;
    return formattedDate;
}

In jQuery 1.5, as long as you have json2.js to cover for older browsers, you can deserialize all dates coming from Ajax as follows:

(function () {
    var DATE_START = "/Date(";
    var DATE_START_LENGTH = DATE_START.length;

    function isDateString(x) {
        return typeof x === "string" && x.startsWith(DATE_START);
    }

    function deserializeDateString(dateString) {
        var dateOffsetByLocalTime = new Date(parseInt(dateString.substr(DATE_START_LENGTH)));
        var utcDate = new Date(dateOffsetByLocalTime.getTime() - dateOffsetByLocalTime.getTimezoneOffset() * 60 * 1000);
        return utcDate;
    }

    function convertJSONDates(key, value) {
      if (isDateString(value)) {
        return deserializeDateString(value);
      }
      return value;
    }

    window.jQuery.ajaxSetup({
      converters: {
        "text json": function(data) {
          return window.JSON.parse(data, convertJSONDates);
        }
      }
    });
}());

I included logic that assumes you send all dates from the server as UTC (which you should); the consumer then gets a JavaScript Date object that has the proper ticks value to reflect this. That is, calling getUTCHours(), etc. on the date will return the same value as it did on the server, and calling getHours() will return the value in the user's local timezone as determined by their browser.

This does not take into account WCF format with timezone offsets, though that would be relatively easy to add.

Updated

We have an internal UI library that has to cope with both Microsoft's ASP.NET built-in JSON format, like /Date(msecs)/, asked about here originally, and most JSON's date format including JSON.NET's, like 2014-06-22T00:00:00.0. In addition we need to cope with oldIE's inability to cope with anything but 3 decimal places.

We first detect what kind of date we're consuming, parse it into a normal JavaScript Date object, then format that out.

1) Detect Microsoft Date format

// Handling of Microsoft AJAX Dates, formatted like '/Date(01238329348239)/'
function looksLikeMSDate(s) {
    return /^\/Date\(/.test(s);
}

2) Detect ISO date format

var isoDateRegex = /^(\d\d\d\d)-(\d\d)-(\d\d)T(\d\d):(\d\d):(\d\d)(\.\d\d?\d?)?([\+-]\d\d:\d\d|Z)?$/;

function looksLikeIsoDate(s) {
    return isoDateRegex.test(s);
}

3) Parse MS date format:

function parseMSDate(s) {
    // Jump forward past the /Date(, parseInt handles the rest
    return new Date(parseInt(s.substr(6)));
}

4) Parse ISO date format.

We do at least have a way to be sure that we're dealing with standard ISO dates or ISO dates modified to always have three millisecond places (see above), so the code is different depending on the environment.

4a) Parse standard ISO Date format, cope with oldIE's issues:

function parseIsoDate(s) {
    var m = isoDateRegex.exec(s);

    // Is this UTC, offset, or undefined? Treat undefined as UTC.
    if (m.length == 7 ||                // Just the y-m-dTh:m:s, no ms, no tz offset - assume UTC
        (m.length > 7 && (
            !m[7] ||                    // Array came back length 9 with undefined for 7 and 8
            m[7].charAt(0) != '.' ||    // ms portion, no tz offset, or no ms portion, Z
            !m[8] ||                    // ms portion, no tz offset
            m[8] == 'Z'))) {            // ms portion and Z
        // JavaScript's weirdo date handling expects just the months to be 0-based, as in 0-11, not 1-12 - the rest are as you expect in dates.
        var d = new Date(Date.UTC(m[1], m[2]-1, m[3], m[4], m[5], m[6]));
    } else {
        // local
        var d = new Date(m[1], m[2]-1, m[3], m[4], m[5], m[6]);
    }

    return d;
}

4b) Parse ISO format with a fixed three millisecond decimal places - much easier:

function parseIsoDate(s) {
    return new Date(s);
}

5) Format it:

function hasTime(d) {
    return !!(d.getUTCHours() || d.getUTCMinutes() || d.getUTCSeconds());
}

function zeroFill(n) {
    if ((n + '').length == 1)
        return '0' + n;

    return n;
}

function formatDate(d) {
    if (hasTime(d)) {
        var s = (d.getMonth() + 1) + '/' + d.getDate() + '/' + d.getFullYear();
        s += ' ' + d.getHours() + ':' + zeroFill(d.getMinutes()) + ':' + zeroFill(d.getSeconds());
    } else {
        var s = (d.getMonth() + 1) + '/' + d.getDate() + '/' + d.getFullYear();
    }

    return s;
}

6) Tie it all together:

function parseDate(s) {
    var d;
    if (looksLikeMSDate(s))
        d = parseMSDate(s);
    else if (looksLikeIsoDate(s))
        d = parseIsoDate(s);
    else
        return null;

    return formatDate(d);
}

The below old answer is useful for tying this date formatting into jQuery's own JSON parsing so you get Date objects instead of strings, or if you're still stuck in jQuery <1.5 somehow.

Old Answer

If you're using jQuery 1.4's Ajax function with ASP.NET MVC, you can turn all DateTime properties into Date objects with:

// Once
jQuery.parseJSON = function(d) {return eval('(' + d + ')');};

$.ajax({
    ...
    dataFilter: function(d) {
        return d.replace(/"\\\/(Date\(-?\d+\))\\\/"/g, 'new $1');
    },
    ...
});

In jQuery 1.5 you can avoid overriding the parseJSON method globally by using the converters option in the Ajax call.

http://api.jquery.com/jQuery.ajax/

Unfortunately you have to switch to the older eval route in order to get Dates to parse globally in-place - otherwise you need to convert them on a more case-by-case basis post-parse.

Everyone of these answers has one thing in common: they all store dates as a single value (usually a string).

Another option is to take advantage of the inherent structure of JSON, and represent a date as list of numbers:

{ "name":"Nick",
  "birthdate":[1968,6,9] }

Of course, you would have to make sure both ends of the conversation agree on the format (year, month, day), and which fields are meant to be dates,... but it has the advantage of completely avoiding the issue of date-to-string conversion. It's all numbers -- no strings at all. Also, using the order: year, month, day also allows proper sorting by date.

Just thinking outside the box here -- a JSON date doesn't have to be stored as a string.

Another bonus to doing it this way is that you can easily (and efficiently) select all records for a given year or month by leveraging the way CouchDB handles queries on array values.

FYI, for anyone using Python on the server side: datetime.datetime().ctime() returns a string that is natively parsable by "new Date()". That is, if you create a new datetime.datetime instance (such as with datetime.datetime.now), the string can be included in the JSON string, and then that string can be passed as the first argument to the Date constructor. I haven't yet found any exceptions, but I haven't tested it too rigorously, either.

Updated

We have an internal UI library that has to cope with both Microsoft's ASP.NET built-in JSON format, like /Date(msecs)/, asked about here originally, and most JSON's date format including JSON.NET's, like 2014-06-22T00:00:00.0. In addition we need to cope with oldIE's inability to cope with anything but 3 decimal places.

We first detect what kind of date we're consuming, parse it into a normal JavaScript Date object, then format that out.

1) Detect Microsoft Date format

// Handling of Microsoft AJAX Dates, formatted like '/Date(01238329348239)/'
function looksLikeMSDate(s) {
    return /^\/Date\(/.test(s);
}

2) Detect ISO date format

var isoDateRegex = /^(\d\d\d\d)-(\d\d)-(\d\d)T(\d\d):(\d\d):(\d\d)(\.\d\d?\d?)?([\+-]\d\d:\d\d|Z)?$/;

function looksLikeIsoDate(s) {
    return isoDateRegex.test(s);
}

3) Parse MS date format:

function parseMSDate(s) {
    // Jump forward past the /Date(, parseInt handles the rest
    return new Date(parseInt(s.substr(6)));
}

4) Parse ISO date format.

We do at least have a way to be sure that we're dealing with standard ISO dates or ISO dates modified to always have three millisecond places (see above), so the code is different depending on the environment.

4a) Parse standard ISO Date format, cope with oldIE's issues:

function parseIsoDate(s) {
    var m = isoDateRegex.exec(s);

    // Is this UTC, offset, or undefined? Treat undefined as UTC.
    if (m.length == 7 ||                // Just the y-m-dTh:m:s, no ms, no tz offset - assume UTC
        (m.length > 7 && (
            !m[7] ||                    // Array came back length 9 with undefined for 7 and 8
            m[7].charAt(0) != '.' ||    // ms portion, no tz offset, or no ms portion, Z
            !m[8] ||                    // ms portion, no tz offset
            m[8] == 'Z'))) {            // ms portion and Z
        // JavaScript's weirdo date handling expects just the months to be 0-based, as in 0-11, not 1-12 - the rest are as you expect in dates.
        var d = new Date(Date.UTC(m[1], m[2]-1, m[3], m[4], m[5], m[6]));
    } else {
        // local
        var d = new Date(m[1], m[2]-1, m[3], m[4], m[5], m[6]);
    }

    return d;
}

4b) Parse ISO format with a fixed three millisecond decimal places - much easier:

function parseIsoDate(s) {
    return new Date(s);
}

5) Format it:

function hasTime(d) {
    return !!(d.getUTCHours() || d.getUTCMinutes() || d.getUTCSeconds());
}

function zeroFill(n) {
    if ((n + '').length == 1)
        return '0' + n;

    return n;
}

function formatDate(d) {
    if (hasTime(d)) {
        var s = (d.getMonth() + 1) + '/' + d.getDate() + '/' + d.getFullYear();
        s += ' ' + d.getHours() + ':' + zeroFill(d.getMinutes()) + ':' + zeroFill(d.getSeconds());
    } else {
        var s = (d.getMonth() + 1) + '/' + d.getDate() + '/' + d.getFullYear();
    }

    return s;
}

6) Tie it all together:

function parseDate(s) {
    var d;
    if (looksLikeMSDate(s))
        d = parseMSDate(s);
    else if (looksLikeIsoDate(s))
        d = parseIsoDate(s);
    else
        return null;

    return formatDate(d);
}

The below old answer is useful for tying this date formatting into jQuery's own JSON parsing so you get Date objects instead of strings, or if you're still stuck in jQuery <1.5 somehow.

Old Answer

If you're using jQuery 1.4's Ajax function with ASP.NET MVC, you can turn all DateTime properties into Date objects with:

// Once
jQuery.parseJSON = function(d) {return eval('(' + d + ')');};

$.ajax({
    ...
    dataFilter: function(d) {
        return d.replace(/"\\\/(Date\(-?\d+\))\\\/"/g, 'new $1');
    },
    ...
});

In jQuery 1.5 you can avoid overriding the parseJSON method globally by using the converters option in the Ajax call.

http://api.jquery.com/jQuery.ajax/

Unfortunately you have to switch to the older eval route in order to get Dates to parse globally in-place - otherwise you need to convert them on a more case-by-case basis post-parse.

TLDR: You cannot reliably convert that date-only value, send a string instead...

...or at least that is how almost all of these answers should start off.

There is a number of conversion issues that are happening here.

This Is a Date Without Time

Something everybody seems to be missing is how many trailing zeros there are in the question - it is almost certainly started out as a date without time:

/Date(1224043200000)/

When executing this from a javascript console as a new Date (the basis of many answers)

new Date(1224043200000)

You get:

The original asker was probably in EST and had a pure date (sql) or a DateTime (not DateTimeOffset) with midnight.

In other words, the intention here is that the time portion is meaningless. However, if the browser executes this in the same timezone as the server that generated it it doesn't matter and most of the answers work.

Bit By Timezone

But, if you execute the code above on a machine with a different timezone (PST for example):

You'll note that we are now a day behind in this other timezone. This will not be fixed by changing the serializer (which will still include timezone in the iso format)

The Problem

Date (sql) and DateTime (.net) do not have timezone on them, but as soon as you convert them to something that does (javascript inferred thru json in this case), the default action in .net is to assume the current timezone.

The number that the serialization is creating is milliseconds since unix epoch or:

(DateTimeOffset.Parse("10/15/2008 00:00:00Z") - DateTimeOffset.Parse("1/1/1970 00:00:00Z")).TotalMilliseconds;

Which is something that new Date() in javascript takes as a parameter. Epoch is from UTC, so now you've got timezone info in there whether you wanted it or not.

Possible solutions:

It might be safer to create a string property on your serialized object that represents the date ONLY - a string with "10/15/2008" is not likely to confuse anybody else with this mess. Though even there you have to be careful on the parsing side: https://stackoverflow.com/a/31732581

However, in the spirit of providing an answer to the question asked, as is:

function adjustToLocalMidnight(serverMidnight){ 
  var serverOffset=-240; //injected from model? <-- DateTimeOffset.Now.Offset.TotalMinutes
  var localOffset=-(new Date()).getTimezoneOffset(); 
  return new Date(date.getTime() + (serverOffset-localOffset) * 60 * 1000)
}

var localMidnightDate = adjustToLocalMidnight(new Date(parseInt(jsonDate.substr(6))));

Click here to check the Demo

JavaScript/jQuery

var = MyDate_String_Value = "/Date(1224043200000)/"
var value = new Date
            (
                 parseInt(MyDate_String_Value.replace(/(^.*\()|([+-].*$)/g, ''))
            );
var dat = value.getMonth() +
                         1 +
                       "/" +
           value.getDate() +
                       "/" +
       value.getFullYear();

Result - "10/15/2008"

Your JSON should probably be returning an object of some sort (well, a string representation thereof).

"{ myDate : Date(1224043200000) }"

Using jQuery, you can access your data object this way:

$.get(
    "myJSONFile.php",
    function (data) {
        // data.myDate will be a date object.

        // to show in a short date format (eg: dd/mm/yyyy)
        alert (
            data.myDate.getDate() + "/"
            + (data.myDate.getMonth() + 1) + "/"
            + data.myDate.getFullYear()
        ); // alerts: "15/10/2008"
    }
);

FYI, for anyone using Python on the server side: datetime.datetime().ctime() returns a string that is natively parsable by "new Date()". That is, if you create a new datetime.datetime instance (such as with datetime.datetime.now), the string can be included in the JSON string, and then that string can be passed as the first argument to the Date constructor. I haven't yet found any exceptions, but I haven't tested it too rigorously, either.

Don't over-think this. Like we've done for decades, pass a numeric offset from the de-facto standard epoch of 1 Jan 1970 midnight GMT/UTC/&c in number of seconds (or milliseconds) since this epoch. JavaScript likes it, Java likes it, C likes it, and the Internet likes it.

var newDate = dateFormat(jsonDate, "mm/dd/yyyy"); 

Is there another option without using the jQuery library?

There is no built in date type in JSON. This looks like the number of seconds / milliseconds from some epoch. If you know the epoch you can create the date by adding on the right amount of time.

What if .NET returns...

return DateTime.Now.ToString("u"); //"2013-09-17 15:18:53Z"

And then in JavaScript...

var x = new Date("2013-09-17 15:18:53Z");

You also can use the JavaScript library moment.js, which comes in handy when you plan do deal with different localized formats and perform other operations with dates values:

function getMismatch(id) {
    $.getJSON("Main.aspx?Callback=GetMismatch",
    { MismatchId: id },

    function (result) {
        $("#AuthMerchId").text(result.AuthorizationMerchantId);
        $("#SttlMerchId").text(result.SettlementMerchantId);
        $("#CreateDate").text(moment(result.AppendDts).format("L"));
        $("#ExpireDate").text(moment(result.ExpiresDts).format("L"));
        $("#LastUpdate").text(moment(result.LastUpdateDts).format("L"));
        $("#LastUpdatedBy").text(result.LastUpdateNt);
        $("#ProcessIn").text(result.ProcessIn);
    }
    );
    return false;
}

Setting up localization is as easy as adding configuration files (you get them at momentjs.com) to your project and configuring the language:

moment.lang('de');

If you say in JavaScript,

var thedate = new Date(1224043200000);
alert(thedate);

you will see that it's the correct date, and you can use that anywhere in JavaScript code with any framework.

As a side note, KendoUI supports to convert Microsoft JSON date. So, If your project has the reference to "KendoUI", you may simply use

var newDate = kendo.parseDate(jsonDate);

In the following code. I have

1. Retrieved the timestamp from the date string.

2. And parsed it into Int

3. Finally Created a Date using it.

var dateString = "/Date(1224043200000)/";_x000D_
var seconds = parseInt(dateString.replace(/\/Date\(([0-9]+)[^+]\//i, "$1"));_x000D_
var date = new Date(seconds);_x000D_
console.log(date);

Your JSON should probably be returning an object of some sort (well, a string representation thereof).

"{ myDate : Date(1224043200000) }"

Using jQuery, you can access your data object this way:

$.get(
    "myJSONFile.php",
    function (data) {
        // data.myDate will be a date object.

        // to show in a short date format (eg: dd/mm/yyyy)
        alert (
            data.myDate.getDate() + "/"
            + (data.myDate.getMonth() + 1) + "/"
            + data.myDate.getFullYear()
        ); // alerts: "15/10/2008"
    }
);

You can use this to get a date from JSON:

var date = eval(jsonDate.replace(/\/Date\((\d+)\)\//gi, "new Date($1)"));

And then you can use a JavaScript Date Format script (1.2 KB when minified and gzipped) to display it as you want.

TLDR: You cannot reliably convert that date-only value, send a string instead...

...or at least that is how almost all of these answers should start off.

There is a number of conversion issues that are happening here.

This Is a Date Without Time

Something everybody seems to be missing is how many trailing zeros there are in the question - it is almost certainly started out as a date without time:

/Date(1224043200000)/

When executing this from a javascript console as a new Date (the basis of many answers)

new Date(1224043200000)

You get:

The original asker was probably in EST and had a pure date (sql) or a DateTime (not DateTimeOffset) with midnight.

In other words, the intention here is that the time portion is meaningless. However, if the browser executes this in the same timezone as the server that generated it it doesn't matter and most of the answers work.

Bit By Timezone

But, if you execute the code above on a machine with a different timezone (PST for example):

You'll note that we are now a day behind in this other timezone. This will not be fixed by changing the serializer (which will still include timezone in the iso format)

The Problem

Date (sql) and DateTime (.net) do not have timezone on them, but as soon as you convert them to something that does (javascript inferred thru json in this case), the default action in .net is to assume the current timezone.

The number that the serialization is creating is milliseconds since unix epoch or:

(DateTimeOffset.Parse("10/15/2008 00:00:00Z") - DateTimeOffset.Parse("1/1/1970 00:00:00Z")).TotalMilliseconds;

Which is something that new Date() in javascript takes as a parameter. Epoch is from UTC, so now you've got timezone info in there whether you wanted it or not.

Possible solutions:

It might be safer to create a string property on your serialized object that represents the date ONLY - a string with "10/15/2008" is not likely to confuse anybody else with this mess. Though even there you have to be careful on the parsing side: https://stackoverflow.com/a/31732581

However, in the spirit of providing an answer to the question asked, as is:

function adjustToLocalMidnight(serverMidnight){ 
  var serverOffset=-240; //injected from model? <-- DateTimeOffset.Now.Offset.TotalMinutes
  var localOffset=-(new Date()).getTimezoneOffset(); 
  return new Date(date.getTime() + (serverOffset-localOffset) * 60 * 1000)
}

var localMidnightDate = adjustToLocalMidnight(new Date(parseInt(jsonDate.substr(6))));

This is frustrating. My solution was to parse out the "/ and /" from the value generated by ASP.NET's JavaScriptSerializer so that, though JSON may not have a date literal, it still gets interpreted by the browser as a date, which is what all I really want:{"myDate":Date(123456789)}

Custom JavaScriptConverter for DateTime?

I must emphasize the accuracy of Roy Tinker's comment. This is not legal JSON. It's a dirty, dirty hack on the server to remove the issue before it becomes a problem for JavaScript. It will choke a JSON parser. I used it for getting off the ground, but I do not use this any more. However, I still feel the best answer lies with changing how the server formats the date, for example, ISO as mentioned elsewhere.

Check up the date ISO standard; kind of like this:

yyyy.MM.ddThh:mm

It becomes 2008.11.20T22:18.

This may can also help you.

 function ToJavaScriptDate(value) { //To Parse Date from the Returned Parsed Date
        var pattern = /Date\(([^)]+)\)/;
        var results = pattern.exec(value);
        var dt = new Date(parseFloat(results[1]));
        return (dt.getMonth() + 1) + "/" + dt.getDate() + "/" + dt.getFullYear();
    }

This uses a regular expression, and it works as well:

var date = new Date(parseInt(/^\/Date\((.*?)\)\/$/.exec(jsonDate)[1], 10));

Posting in awesome thread:

var d = new Date(parseInt('/Date(1224043200000)/'.slice(6, -2)));
alert('' + (1 + d.getMonth()) + '/' + d.getDate() + '/' + d.getFullYear().toString().slice(-2));

I ended up adding the "characters into Panos's regular expression to get rid of the ones generated by the Microsoft serializer for when writing objects into an inline script:

So if you have a property in your C# code-behind that's something like

protected string JsonObject { get { return jsSerialiser.Serialize(_myObject); }}

And in your aspx you have

<script type="text/javascript">
    var myObject = '<%= JsonObject %>';
</script>

You'd get something like

var myObject = '{"StartDate":"\/Date(1255131630400)\/"}';

Notice the double quotes.

To get this into a form that eval will correctly deserialize, I used:

myObject = myObject.replace(/"\/Date\((\d+)\)\/"/g, 'new Date($1)');

I use Prototype and to use it I added

String.prototype.evalJSONWithDates = function() {
    var jsonWithDates = this.replace(/"\/Date\((\d+)\)\/"/g, 'new Date($1)');
    return jsonWithDates.evalJSON(true);
}

A late post, but for those who searched this post.

Imagine this:

    [Authorize(Roles = "Administrator")]
    [Authorize(Roles = "Director")]
    [Authorize(Roles = "Human Resources")]
    [HttpGet]
    public ActionResult GetUserData(string UserIdGuidKey)
    {
        if (UserIdGuidKey!= null)
        {
            var guidUserId = new Guid(UserIdGuidKey);
            var memuser = Membership.GetUser(guidUserId);
            var profileuser = Profile.GetUserProfile(memuser.UserName);
            var list = new {
                              UserName = memuser.UserName,
                              Email = memuser.Email ,
                              IsApproved = memuser.IsApproved.ToString() ,
                              IsLockedOut = memuser.IsLockedOut.ToString() ,
                              LastLockoutDate = memuser.LastLockoutDate.ToString() ,
                              CreationDate = memuser.CreationDate.ToString() ,
                              LastLoginDate = memuser.LastLoginDate.ToString() ,
                              LastActivityDate = memuser.LastActivityDate.ToString() ,
                              LastPasswordChangedDate = memuser.LastPasswordChangedDate.ToString() ,
                              IsOnline = memuser.IsOnline.ToString() ,
                              FirstName = profileuser.FirstName ,
                              LastName = profileuser.LastName ,
                              NickName = profileuser.NickName ,
                              BirthDate = profileuser.BirthDate.ToString() ,
            };
            return Json(list, JsonRequestBehavior.AllowGet);
        }
        return Redirect("Index");
    }

As you can see, I'm utilizing C# 3.0's feature for creating the "Auto" Generics. It's a bit lazy, but I like it and it works. Just a note: Profile is a custom class I've created for my web application project.

Add the jQuery UI plugin in your page:

function DateFormate(dateConvert) {
    return $.datepicker.formatDate("dd/MM/yyyy", eval('new ' + dateConvert.slice(1, -1)));
};

var obj = eval('(' + "{Date: \/Date(1278903921551)\/}".replace(/\/Date\((\d+)\)\//gi, "new Date($1)") + ')');
var dateValue = obj["Date"];

In the following code. I have

1. Retrieved the timestamp from the date string.

2. And parsed it into Int

3. Finally Created a Date using it.

var dateString = "/Date(1224043200000)/";_x000D_
var seconds = parseInt(dateString.replace(/\/Date\(([0-9]+)[^+]\//i, "$1"));_x000D_
var date = new Date(seconds);_x000D_
console.log(date);

If you are using Kotlin then this will solve your problem.

val dataString = "/Date(1586583441106)/"
val date = Date(Long.parseLong(dataString.substring(6, dataString.length - 2)))

I also had to search for a solution to this problem and eventually I came across moment.js which is a nice library that can parse this date format and many more.

var d = moment(yourdatestring)

It saved some headache for me so I thought I'd share it with you. :)
You can find some more info about it here: http://momentjs.com/

This uses a regular expression, and it works as well:

var date = new Date(parseInt(/^\/Date\((.*?)\)\/$/.exec(jsonDate)[1], 10));

Check up the date ISO standard; kind of like this:

yyyy.MM.ddThh:mm

It becomes 2008.11.20T22:18.

There is no built in date type in JSON. This looks like the number of seconds / milliseconds from some epoch. If you know the epoch you can create the date by adding on the right amount of time.