ville lige prøve min umildbare ide, og det virkede med en mindre omskrivning, komplet code:
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=utf-8"/>
<title></title>
<style type="text/css">
</style>
<script type="text/javascript">
//<![CDATA[
function deleteOption(obj,index) {
var object = document.getElementById(obj);
object.options[index] = null;
}
function addOption(obj,text,value) {
var object = document.getElementById(obj);
var defaultSelected = true;
var selected = true;
var optionName = new Option(text, value, defaultSelected, selected)
object.options[object.length] = optionName;
}
function copySelected(fromObject,toObject) {
var From = document.getElementById(fromObject);
var To = document.getElementById(toObject);
var FromLng = From.length;
for(var i=0, l=FromLng;i<l;i++){
if (From[i].selected) {
addOption(toObject,From.options[i].text,From.options[i].value);
}
}
for (var i=FromLng-1;i>-1;i--) {
if (From[i].selected){
deleteOption(fromObject,i);
}
}
}
function SelectAll(fromObject) {
var From = document.getElementById(fromObject);
for(var i=0, l=From.length;i<l;i++){
From.options[i].selected = true;
}
}
//]]>
</script>
</head>
<body>
<form name ="frm" method="post" action="req.php">
<table>
<tr>
<td>Mine livretter<br>
<select multiple="multiple" name="select1[]" id="select1[]" size='8' style="width:200px">
<option value='1'>Indisk curry</option>
<option value='2'>Pasta med pesto</option>
<option value='3'>Humus</option>
</select>
</td>
<td>
<input type='button' style="width:70px;" value='< Tilføj'
onclick="copySelected('select2[]','select1[]')">
<br>
<input type='button' style="width:70px;" value='Fjern >'
onclick="copySelected('select1[]','select2[]')">
</td>
<td>Tilgængelige retter<br>
<select multiple="multiple" name="select2[]" id="select2[]" size='8' style="width:200px">
<option value='4'>Pasta med ketchup</option>
<option value='5'>Lasagne</option>
<option value='6'>Big mac</option>
<option value='7'>Whopper med cheese</option>
<option value='8'>Pizza</option>
<option value='9'>Shawarma</option>
</select>
</td>
</tr>
</table>
<p><input type="button" value="Send data" onclick="SelectAll('select1[]'); submit();">
</form>
</body>
</html>
demo
http://olsensweb.dk/test/experten/spm/943671/nb: vær kritisk når du anvender code fra html.dk (sidst opdateret 2001)