If that number represents milliseconds, use the Date's constructor :

var myDate = new Date(1238540400000);

You need to extract the number from the string, and pass it into the Date constructor:

var x = [{
"id": 1,
"start": "\/Date(1238540400000)\/"
}, {
"id": 2,
"start": "\/Date(1238626800000)\/"
}];


var myDate = new Date(x[0].start.match(/\d+/)[0] * 1);

The parts are:

x[0].start                                - get the string from the JSON
x[0].start.match(/\d+/)[0]                - extract the numeric part
x[0].start.match(/\d+/)[0] * 1            - convert it to a numeric type
new Date(x[0].start.match(/\d+/)[0] * 1)) - Create a date object

If you use jQuery

In case you use jQuery on the client side, you may be interested in this blog post that provides code how to globally extend jQuery's $.parseJSON() function to automatically convert dates for you.

You don't have to change existing code in case of adding this code. It doesn't affect existing calls to $.parseJSON(), but if you start using $.parseJSON(data, true), dates in data string will be automatically converted to Javascript dates.

It supports Asp.net date strings: /Date(2934612301)/ as well as ISO strings 2010-01-01T12_34_56-789Z. The first one is most common for most used back-end web platform, the second one is used by native browser JSON support (as well as other JSON client side libraries like json2.js).

Anyway. Head over to blog post to get the code. http://erraticdev.blogspot.com/2010/12/converting-dates-in-json-strings-using.html

I use this:

function parseJsonDate(jsonDateString){
return new Date(parseInt(jsonDateString.replace('/Date(', '')));
}

Update 2018:

This is an old question. Instead of still using this old non standard serialization format I would recommend to modify the server code to return better format for date. Either an ISO string containing time zone information, or only the milliseconds. If you use only the milliseconds for transport it should be UTC on server and client.

  • 2018-07-31T11:56:48Z - ISO string can be parsed using new Date("2018-07-31T11:56:48Z") and obtained from a Date object using dateObject.toISOString()
  • 1533038208000 - milliseconds since midnight January 1, 1970, UTC - can be parsed using new Date(1533038208000) and obtained from a Date object using dateObject.getTime()