ASP.NET Parse DateTime result from ajax call to javascript date

Use convertToJavaScriptDate() function that does this for you:

function convertToJavaScriptDate(value) {
  var pattern = /Date\(([^)]+)\)/;
  var results = pattern.exec(value);
  var dt = new Date(parseFloat(results[1]));
  return (dt.getMonth() + 1) + "/" + dt.getDate() + "/" + dt.getFullYear();
}

The convertToJavaScriptDate() function accepts a value in \/Date(ticks)\/ format and returns a date string in MM/dd/yyyy format.
Inside, the convertToJavaScriptDate() function uses a regular expression that represents a pattern /Date\(([^)]+)\)/.
The exec() method accepts the source date value and tests for a match in the value. The return value of exec() is an array. In this case the second element of the results array (results[1]) holds the ticks part of the source date.

For example, if the source value is \/Date(836418600000)\/ then results[1] will be 836418600000.
Based on this ticks value a JavaScript Date object is formed. The Date object has a constructor that accepts the number of milliseconds since 1 January 1970.
Thus dt holds a valid JavaScript Date object.
The convertToJavaScriptDate() function then formats the date as MM/dd/yyyy and returns to the caller.

You can use the convertToJavaScriptDate() function as shown below:

options.success = function (order) {
 alert("Required Date : " + convertToJavaScriptDate(order.RequiredDate) + ", Shipped Date : " + convertToJavaScriptDate(order.ShippedDate));
};

Although the above example uses date in MM/dd/yyyy format, you can use other formats also once Date object is constructed.

reference : Link

You could try this:

   _$.ajax({
        url: 'Default.aspx/GetPerson',
        type: "POST",
        dataType: "json",
        contentType: "application/json; charset=utf-8",
        success: function (data) {
            console.log(JSON.stringify(data.d));
            var src = data.d.Birthday;
            //Remove all non-numeric (except the plus)
            src = src.replace(/[^0-9 +]/g, ''); 
            //Create date
            var birthDate = new Date(parseInt(src));
            self.html(birthDate);
        }
    });

JSFiddle