Get the datafield of check boxes that checked in datagrid(with java script)?

[ahmad_n80]

i have a datagrid that have some checkboxes.
i introduce the check boxes in datagrid like:
<ItemTemplate>
<asp:CheckBox ID="chk" runat="server"></asp:CheckBox>
</ItemTemplate>
how can i get the datafield(like id) of check boxes that checked, from database(with java script)
thanks.