<SELECT id=select1 name=select1 style="WIDTH: 40px" multiple>
<OPTION value=11 selected>11</OPTION><OPTION
value=22>22</OPTION><OPTION value=33>33</OPTION>
</SELECT>
<SELECT id=select2 name=select2 multiple>
</SELECT>
<INPUT type="button" value="Button" id=button1 name=button1 onclick="addslt()"><script language=javascript>
function addslt(){
for (var i=0; i < select1.options.length; ++i){
if (select1.options[i].selected){
var selection = select1.options[i].text;
select2.options[select2.options.length] = new Option(selection);
}
}
}
</script>
<OPTION value=11 selected>11</OPTION><OPTION
value=22>22</OPTION><OPTION value=33>33</OPTION>
</SELECT>
<SELECT id=select2 name=select2 multiple>
</SELECT>
<INPUT type="button" value="Button" id=button1 name=button1 onclick="addslt()"><script language=javascript>
function addslt(){
for (var i=0; i < select1.options.length; ++i){
if (select1.options[i].selected){
var selection = select1.options[i].text;
select2.options[select2.options.length] = new Option(selection);
}
}
}
</script>
function addslt(){
for(var i=0;i<select1.options.length;i++){
if(select1.options[i].selected){
select2.appendChild(select1.options[i])
}
}
}
<head>
<script>
function addOption()
{
var the_option= new Option(select1.value,select1.value);
select2.add(the_option);
select2.selectedIndex = select2.options.length-1
}
</script>
</head>
<body>
<select name=select1>
<option value='aaaaa'>aaaaa</option>
<option value='bbbbb'>bbbbb</option>
<option value='ccccc'>ccccc</option>
<option value='ddddd'>ddddd</option>
<option value='eeeee'>eeeee</option>
</select>
<input type=button value="==>" onclick="addOption()">
<select name=select2 onchange="alert(this.value)"></select>
</body>
</html>
function addOption(e){
var oCloneNode=e.options[e.selectedIndex].cloneNode(true);
document.all.select2.insertBefore(oCloneNode);
}
</script>
<select name=select1 onchange="addOption(this)">
<option ></option>
<option>aaaaa</option>
<option>bbbbb</option>
<option>ccccc</option>
<option>ddddd</option>
<option>eeeee</option>
</select>
<select name=select2></select>