Javascript for calculating age

<script type="text/javascript">
       function showAge() {
          
           var d = document.getElementById('<%= txtDateOfBirth.ClientID %>').value.split('/');
           var today = new Date();
           var bday = new Date(d[2], d[1], d[0]);
           var by = bday.getFullYear();
           var bm = bday.getMonth() - 1;
           var bd = bday.getDate();
           var age = 0; var dif = bday;
           while (dif <= today) {
               var dif = new Date(by + age, bm, bd);
               age++;
           }
           age += -2;
           document.getElementById("<%=txtCurrentAge.ClientID %>").value = age;
           alert('You are ' + age + ' years old')
       }
</script>

//On page load write this..

this.txtDateOfBirth.Attributes.Add("OnBlur", "javascript:return  showAge();");

Validation on Checkbox

 <script language="javascript" type="text/javascript"> 

function validateCheckBox1(source, args)
        {

            args.IsValid = document.getElementById('<%= Chk1.ClientID %>').checked;

        }

</script>

// call this with custom validator in HTML page

CheckBox ID="Chk1" runat="server" />
                      

<asp:CustomValidator runat="server" ID="CustomValidator4" Visible="true"
ClientValidationFunction="validateCheckBox2"
 ErrorMessage="Please confirm the authorisation 1" Display="Dynamic"  />

Validation in Radiobutton List

<script language="javascript" type="text/javascript">

 function ValidateRadioButtonListSIALenece() {
            var RBL = document.getElementById('<%= RbtnSIA.ClientID %>');
            var radiobuttonlist = RBL.getElementsByTagName("input");
            var counter = 0;
            var atLeast = 1;
            for (var i = 0; i < radiobuttonlist.length; i++) {
                if (radiobuttonlist[i].checked) {

                    if (radiobuttonlist[i].value == "Yes") {
                        // alert('y');
                        document.getElementById("<%=txtDateOfApplication.ClientID %>").value = "";
                        document.getElementById("<%=txtDateOfApplication.ClientID %>").readOnly = false;
                        document.getElementById("<%=Img29.ClientID %>").style.visibility = 'visible';
                        document.getElementById("<%=RegularExpressionValidator10.ClientID %>").readOnly = false;

                    }
                    if (radiobuttonlist[i].value == "No") {
                        // alert('N');
                        document.getElementById("<%=txtDateOfApplication.ClientID %>").value = "";
                        document.getElementById("<%=txtDateOfApplication.ClientID %>").readOnly = true;
                        document.getElementById("<%=Img29.ClientID %>").style.visibility = 'hidden';
                        document.getElementById("<%=RegularExpressionValidator10.ClientID %>").readOnly = true;

                    }

                    counter++;
                }
            }

        }

</script>

I am calling this on radiobutton list click event

this.RBtnList.Attributes.Add("OnClick", "javascript:return  ValidateRadioButtonListSIALenece();");