Jquery validate for gridview inner control(Lable,Textbox) on button click Event

   $('#btnSubmit').click(function () {
             var isValid = true;
                $("table[id$='gvPurchase']").find("span.validate").each(function () {
                //span use for lable control and validate is class of the control
                // <asp:Label ID="Label2" runat="server" class="validate" Text="0"></asp:Label>               
                    if ($(this).html() == "") {
                        $("#gvValidate").html("*Rate and quantity not be null");
                        isValid = false;
                    }
                    if (parseInt($(this).html()) <= 0) {

                        $("#gvValidate").html("*Rate and quantity must be grater then zero");
                        isValid = false;
                    }

                });