i used javascript function to get the value but how will i receive the value in the asp. txtto is the name of the textbox
<script>
function disp()
{
a= document.form1.txtto.value;
alert(a);
return a ;
}
</script>

<%
<a href= "email_1.asp?id=<%=response.write(value)%> " onClick="disp();">
%>

but how will i receive the value returned from disp function

you are trying to pass variable data between server and client codes.

one way to do this is to use an HTML <Input type="hidden"> text box as an intermediate holding place and refer to your data by using this text box's value in either the client or server codes.

You may also use session variables, that are more safe to store the variable value.

Paulo

In your case, I think it is better to use the form instead of the link. When the form is submited, you still can pop up an ALERT window to the user.