or
<telerik:RadScriptManager ID="RadScriptManager1" Runat="server" ViewStateMode="Enabled" EnableViewState="true"><br> </telerik:RadScriptManager>$('.check-all').click(function () { var checkbox = $(this).find('input:checkbox:first') $('.RadComboBox').each(function () { var combo = this.control; if (checkbox.is(':checked')) { combo.disable(); } else { combo.enable(); } });$('#<%= cbxOne.ClientID %>').click(function () { var combo = $find("<%= cmbOne.ClientID %>"); if ($(this).is(':checked')) { combo.disable(); } else { combo.enable(); }})