Serialize all id's in a div using jquery

Answer 1

$(function() {
    $('#contentLeft ul').sortable({
        update: function() {
            var order3 = [];
            $('#contentLeft ul li').each(function(){
                order3.push($(this).attr('id').replace(/_/g, '[]='))
            });
            alert(order3.join('&'));
        }
    });
});

try here: http://jsfiddle.net/MXCZx/1/