codice:
<form action="acquista_utente.asp" name="form2" method="POST"  onSubmit="return checkForm1(this);">
<script language="javascript">
<!--
function checkForm1(f){
var Ora = f.ora.value;
if (Ora == "inserisci"){
alert("Inserire l'ora di consegna");
f.ora.focus();
f.ora.style.border="1px dashed #f08223";
return false;
}
f.ora.style.border="1px dashed #ffffff";
}
// -->
</script>
<div id="div_in">
<select name="ora" id="ora">
    <option id="ora" name="ora" value="inserisci" selected >inserisci ora consegna</option>
       </select>
</div>
<input type="submit" value="Acquista">
</form>