Allow text box only for alphabets using Jquery

$(document).ready(function () {

        $('#<%= txtNoofDays.ClientID  %>').keypress(function (e) {

            if (e.which != 8 && e.which != 0 && (e.which < 48 || e.which > 57)) {

                //display error message

                $("#errmsg").html("Digits Only").show().fadeOut("slow");

                return false;

            }

        });

       

    });

<asp:TextBox ID="txtNoofDays" runat="server"></asp:TextBox>

                        &nbsp;<span id="errmsg" style="color:Red;"></span>