validate atleast on selection inside gridview using javascript

//Gridview

<asp:TemplateField >

 <ItemTemplate>

 <asp:CheckBox runat="server" ID="Chk_allCh" />

  </ItemTemplate>

 <HeaderTemplate>

 <asp:CheckBox runat="server" ID="Chk_all" onclick="checkAllRow(this);" />

</HeaderTemplate>

</asp:TemplateField>

//Script

function checkvalidateSelect() {

        var gridView = document.getElementById('<%=GridViewID.ClientID %>');

                    

                    var isValid = false;

                    for (var i = 1; i < gridView.rows.length; i++) {

                        var inputs = gridView.rows[i].getElementsByTagName('input');

                        if (inputs != null) {

                            if (inputs[0].type == "checkbox") {

                                if (inputs[0].checked) {

                                    isValid = true;

                                    break;

                                }

                            }

                        }

                    }

                    if (!isValid) {

                 alert('Please select at least one');

                        return false;

                    }

                    else

                    { return true; }

                }