Esempio:
codice:
<head>
<script>
function s2d() {
	f=document.f1;
	for (var si=0;si<f.sin.options.length;si++) {
		if(f.sin.options[si].selected) {
			sv=f.sin.options[si].value;
			st=f.sin.options[si].text;
			f.des.options[f.des.length] = new Option(st,sv);
			f.sin.options[si] = null;
			f.des.selectedIndex=f.des.length-1;
			si--
		}
	}
}
</script>

</HEAD>

<BODY>
<form name=f1>
<select name=sin size=10 multiple>
<option value=1>uno</option>
<option value=2>due</option>
<option value=3>tre</option>
<option value=6>sei</option>
</select>
<input type=button value="->" onclick="s2d()">
<select name=des size=10></select>
</form>
</BODY>
ciao