<html>
<form name='forma' method='get' action='entrada.asp' onSubmit="return enviar(this);">
<input type=text name='txt_user' id='txt_user' value=''>
<input type=submit value='Entrar'>
</form>
<script>
function enviar(frm)
{
switch(frm.txt_user.value.length)
{
case 8:
frm.action="ocho.asp";
break;
case 9:
frm.action="nueve.asp";
break;
}
frm.submit();
return false;
}
</script>
</html>