Trigger Button Click event on TextBox Enter Key Press in ASP.Net

 hi

how to get the enter key event in asp.net. so far i tried lot of codes... but unfornunately none of the code is performing the enter key event. would you provide accurate code to fire enter key event when i subit the login button. otherwise say wh mistake i had done in below code.

<script type="text/javascript">
$(document).keypress(function(e) {
   if (e.keyCode === 13) {
        $("#<%= login.ClientID %>").click();
       return false;
    }
});
</script>
    <script type="text/javascript">
$(function() {
    $('#txtpass').keypress(function (event) {
if (event.keyCode == 13) {
    $('#login').click();
}
})
})
</script>  
<script type="text/javascript">
    var input = document.getElementById("txtpass");
input.addEventListener("keyup", function(event) {
    event.preventDefault();
    if (event.keyCode === 13) {
        document.getElementById("login").click();
    }
});
</script>  
 <script type="text/javascript">
     function enterEvent(e) {
         if (e.keyCode == 13) {
             $("input[id=login]").click();
         }
     }
</script>

        <tr>
            <td colspan="3"> <asp:Label ID="Label1" runat="server" Text="USERNAME" Font-Bold="True"></asp:Label></td>
             <td> <asp:TextBox ID="txtusername" runat="server"></asp:TextBox></td>
             <td><asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server" ErrorMessage="Enter Username" ControlToValidate="txtusername"></asp:RequiredFieldValidator></td>
         </tr>
         <tr><td><br /></td></tr>
         <tr>
            <td colspan="3"> <asp:Label ID="Label2" runat="server" Text="PASSWORD" Font-Bold="True"></asp:Label></td>
             <td> <asp:TextBox ID="txtpass" TextMode="Password" runat="server"></asp:TextBox></td>
             <td><asp:RequiredFieldValidator ID="RequiredFieldValidator2" runat="server" ErrorMessage="Enter Password" ControlToValidate="txtpass"></asp:RequiredFieldValidator></td>
         </tr>
         <tr><td><br /></td></tr>
         <tr>
             <td></td>
             <td colspan="3"><asp:Button id="btnback" runat="server" CssClass="bck bck_btn bck_large" text="Go Back" OnClientClick="JavaScript: window.history.back(1); return false;"/></td>
            <td><asp:Button ID="login" runat="server" CssClass="log log_btn log_large" OnClick="login_Click" Text="LOGIN"/></td>
         </tr>

        protected void Page_Load(object sender, EventArgs e)
        {
            Label3.Visible = false;
            txtpass.Attributes.Add("onkeypress", "return controlEnter('" + login.ClientID + "', event)");
        }