JSON list sorting with javascript

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C#

Javascript

SQL

Ajax

JSON

Hey guys, Im struggling with this problem and could do with some advice. Ive done some searching and havent found what im looking for so I figured this was the next stop.

After removing the unimportant parts my code looks something like this. the Ajax goes to my serverside GetProducts function which returns a serialized string of JSON. Which is a List of items which a Select statement filled from a SQL database.

$.ajax({
        type: 'POST',
        url: 'Answer.aspx/GetProducts',
        data: JSON.stringify({ id: ID }),
        contentType: 'application/json; charset=utf-8',
        dataType: 'json',
        success: function (msg) {

        document.getElementById("hfProducts").value = msg.d;

        document.getElementById("ulList").innerHTML = "";
        var data = eval('(' + document.getElementById("hiddenfieldOfProducts").value + ')');

        $.each(data, function (i, item) {
        var message = "<li>" + 
                           "<div  style=" + " width:100%;" + ">" +
                           item.ProductName+"  £" + item.ProductPrice+
                            " </div> " + 
                      "</li>  ";

         document.getElementById("ulList").innerHTML += message;
         var newcontent = document.createElement('li');
          });
        }
 });

At some point in the process before I start displaying the List items in a long unorganised list.Now I want to split up the items and sort the data based off the Category of the product so It would output like this, with the bold text the category:

Food:
Chicken pie £4.00
Roast Dinner £7.00
Chilli and rice £5.00

Desert
Apple pie £2.00
Ice cream £3.00

KitchenWare
Wok £15.00
Pan £10.00

You get the idea, currently they come through in the order they were added to the database based off the unique ID, I want to split them up based off the item.Category and display them like above with the Category title above that section.

Can I get some advice on what im doing here? I've spent hours today trying to work on this problem without much success. Since C# doesn't allow you to return multiple lists at the same time in a return statement and I don't want to resort to a lot of repeating code I need advice from someone with more experience.#

Hopefully I was clear enough, Thanks in advance.