Codice PHP:
<script language = "javascript" type="text/javascript">
function getValue(){
alert(document.getElementById('subSelection').options[document.getElementById('subSelection').selectedIndex].text);
}
</script>
<select id="subSelection">
<option value="1">Nome_1</option>
<option value="2">Nome_2</option>
<option value="3">Nome_3</option>
</select>
<input type="button" onclick="getValue();">