Login validation

   <script type="text/javascript">
        function validateUserName() {
            var name = document.getElementById('<%=txtUserName.ClientID %>').value;
            if (name == "") {
                document.getElementById("spanNameMsg").innerHTML = "*Please input user name.";
                return false;
            }
            else {
                document.getElementById("spanNameMsg").innerHTML = "";
                return true;
            }
        }
        function validatePassword() {
            var password = document.getElementById('<%=txtPassword.ClientID %>').value;
            if (password == "") {
                document.getElementById("passMsg").innerHTML = "*Please input password.";
                return false;
            }
            else if (!IsValidPassword(password)) {
            return false;
            }
            else {
                document.getElementById("passMsg").innerHTML = "";
                return true;
            }
        }
        function validateForm() {
            var bReturn = true;
            if (!validateUserName()) {
                bReturn = false;
            }

            if (!validatePassword()) {
                bReturn = false;
            }
            return bReturn;
        }

        var anUpperCase = /[A-Z]/;
        var aLowerCase = /[a-z]/;
        var aNumber = /[0-9]/;
        var aSpecial = /[!|@|#|$|%|^|&|*|(|)|-|_]/;

        function IsValidPassword(obj) {
            if (obj.length < 8) {
                document.getElementById("passMsg").innerHTML = "password cannot less than 8 bits.";
                return false;
            }
            if (!anUpperCase.test(obj) && !aLowerCase.test(obj)) {
                document.getElementById("passMsg").innerHTML = "password must contain letter (a-z) or (A-Z).";
                return false;
            }
            if (!aSpecial.test(obj)) {
                document.getElementById("passMsg").innerHTML = "password must contain special characters.";
                return false;
            }
            if (!aNumber.test(obj)) {
                document.getElementById("passMsg").innerHTML = "password must contain number.";
                return false;
            }
            return true;
        }

    </script>

 

 

    <style type="text/css">
        .errMsg
        {
            color: Red;
            font-size: 12px;
        }
    </style>

 

 

  <div>
        <table>
            <tr>
                <td>
                    UserName:
                </td>
                <td>
                    <asp:TextBox ID="txtUserName" runat="server" onblur="validateUserName()" onclick="validateUserName()"></asp:TextBox>
                    <span id="spanNameMsg" class="errMsg"></span>
                </td>
            </tr>
            <tr>
                <td>
                    Password:
                </td>
                <td>
                    <asp:TextBox ID="txtPassword" runat="server" onblur="validatePassword()" onclick="validatePassword()"></asp:TextBox>
                    <span id="passMsg" class="errMsg"></span>
                </td>
            </tr>
            <tr>
                <td>
                </td>
                <td>
                    <asp:Button ID="btnLogin" runat="server" Text="Login" OnClientClick="javascript:return validateForm();" />
                </td>
            </tr>
        </table>
    </div>

 

For login validation