How to access the key of ListItems in CheckBoxList

I need to access the key values of the individual Checkboxes in my CheckBoxList in the client. How do I do this please? The code below works to select the text however, I want to access the integer values as below please.

<asp:CheckBoxList id=rbGender runat="server" Width="200px" RepeatDirection="Horizontal">
<asp:Li开发者_Python百科stItem Value="-1">-1</asp:ListItem>
<asp:ListItem Value="0">Female</asp:ListItem>
<asp:ListItem Value="1">Male</asp:ListItem>
</asp:CheckBoxList>



 function getCheckBoxListItemsChecked(elementId) {
            var elementRef = document.getElementById(elementId);
            var checkBoxArray = elementRef.getElementsByTagName('input');
            var checkedValues = '';

            for (var i = 0; i < checkBoxArray.length; i++) {
                var checkBoxRef = checkBoxArray[i];

                if (checkBoxRef.checked == true) {
                    var labelArray = checkBoxRef.parentNode.getElementsByTagName('label');
                    if (labelArray.length > 0) {
                        if (checkedValues.length > 0)
                            checkedValues += ', ';
                        checkedValues += labelArray[0].innerHTML;
                    }
                }
            }

            return checkedValues;
        }


        function CopyItemsToTextBox() {
            var checkedItems = getCheckBoxListItemsChecked('<%= rbGender.ClientID %>');
            alert('Items checked: ' + checkedItems);

            return checkedItems;
        }

try this jQuery code for single element selection

$("input:checked","[id$='rbGender']").val()

and this for multiple. each will loop through each selected checkbox

$.each($("input:checked","[id$='rbGender']"), function(k, v) { 
  alert(v.value); 
});