Client side validation using javascript

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

function validate2()

{

     

      if (document.getElementById("<%=txtName.ClientID%>").value=="")

      {

                 alert("Enter First Name");

                 document.getElementById("<%=txtName.ClientID%>").focus();

                 return false;

      }

                 

      if (document.getElementById("<%=txtEmail.ClientID%>").value=="")

      {

                 alert("Enter Email");

                 document.getElementById("<%=txtEmail.ClientID%>").focus();

                 return false;

      }

        var emailPat = /^[^@]+@[^@.]+\.[^@]*\w\w$/  ;   

        var emailid=document.getElementById("<%=txtEmail.ClientID %>").value;

        var matchArray = emailid.match(emailPat);

        if (matchArray == null)

        {               

                   alert("Enter Correct Email");

                   document.getElementById("<%=txtEmail.ClientID %>").focus();

                   return false;

        }

       

        if (document.getElementById("<%=txtSubject.ClientID%>").value=="")

      {

                 alert("Enter Subject");

                 document.getElementById("<%=txtSubject.ClientID%>").focus();

                 return false;

      }

        return true;

}

</script>

<table width="90%" border="0" align="center" cellpadding="2" cellspacing="0">

                                        <tr>

                                            <td width="30%">

                                                <strong>Name :</strong></td>

                                            <td width="70%">

                                                <asp:TextBox ID="txtName" runat="server" CssClass="text_field" Style="width: 250px"></asp:TextBox>

                                            </td>

                                        </tr>

                                        <tr>

                                            <td>

                                                <strong>Email ID :</strong></td>

                                            <td>

                                                <asp:TextBox ID="txtEmail" runat="server" CssClass="text_field" Style="width: 250px"></asp:TextBox>

                                            </td>

                                        </tr>

                                        <tr>

                                            <td>

                                                <strong>Subject :</strong></td>

                                            <td>

                                                <asp:TextBox ID="txtSubject" runat="server" CssClass="text_field" Style="width: 250px"></asp:TextBox>

                                            </td>

                                        </tr>

                                        <tr>

                                            <td>

                                                <strong>Description :</strong></td>

                                            <td>

                                                <asp:TextBox ID="txtDescription" runat="server" TextMode="MultiLine" CssClass="text_field"

                                                    Style="width: 350px"></asp:TextBox>

                                            </td>

                                        </tr>

                                        <tr>

                                            <td>

                                                &nbsp;</td>

                                            <td>

                                                &nbsp;</td>

                                        </tr>

                                        <tr>

                                            <td>

                                                &nbsp;</td>

                                            <td>

                                                <asp:ImageButton ID="imgbtnSend" runat="server" OnClientClick="return validate2()" ImageUrl="images/send.png" Width="46"

                                                    Height="24" border="0" OnClick="imgbtnSend_Click" />

                                                <asp:ImageButton ID="imgbtnReset" runat="server" ImageUrl="images/send.png" Width="46"

                                                    Height="24" border="0" OnClick="imgbtnReset_Click" />

                                            </td>

                                        </tr>

                                        <tr>

                                            <td>

                                                &nbsp;</td>

                                            <td>

                                                &nbsp;</td>

                                        </tr>

                                    </table>