codice:
<HTML>
	<HEAD>
		<SCRIPT Language="JavaScript"> 
			function Visualizza(obj){
				alert("obj.options[obj.selectedIndex].value: " + obj.options[obj.selectedIndex].value)
				if(obj.options[obj.selectedIndex].value != 0){
					alert("pianeta selezionato: " + obj.options[obj.selectedIndex].value)
					F1.stato.options[0].selected = true
					alert("pianeta: "+ document.F1.pianeti.options[obj.selectedIndex].value)

				}
			}
		</SCRIPT>
	</HEAD>
	<BODY>
		<FORM NAME="F1">
			<SELECT NAME="pianeti" onChange="Visualizza(this)">
				<OPTION SELECTED> nessun pianeta</OPTION>
				<option value="marte">Marte</option>
				<option value="venere">Venere</option>
				<option value="giove">Giove</option>
			</SELECT>
			<SELECT NAME="stato">
				<OPTION value="pianetaSelezionato"> Pianeta selezionato
				<OPTION value="PianetaDaSelezionare" SELECTED> Pianeta da selezionare
			</SELECT>
		</FORM>
	</BODY>
</HTML>