codice:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" lang="it">
<head>
<title></title>
<meta http-equiv="Content-type" content="text/html; charset=iso-8859-1" />
</head>
<body >
<div align="center">
<form name="agreeform" action="">
<fieldset><legend>Linkd dinamico</legend>
<select name="lista-siti" id="lista-siti">
<option value="0">====</option>
<option value="http://www.google.it">sito 1</option>
<option value="http://www.virgilio.it">sito 2</option>
<option value="http://www.html.it">sito 3</option>
<option value="4">sito 4</option>
<option value="5">sito 5</option>
<option value="6">6</option>
<option value="7">7</option>
<option value="8">8</option>
<option value="9">9</option>
</select>
<input type="button" name="invia" id="invia" value="Vai!" onclick="if(document.getElementById('lista-siti').selectedIndex!=0){location.href=document.getElementById('lista-siti').options[document.getElementById('lista-siti').selectedIndex].value}else{alert('Seleziona un sito');}">
</fieldset>
</form>
</div>