如何让一个列表框的选定的值，添加到另一个列表框中

Question

<script language="javascript">
function add(){
document.form1.slt2.option=new Option(document.form1.slt1.options[document.form1.slt1.selectedIndex].text,document.form1.slt1.options[document.form1.slt1.selectedIndex].value);
}

Answer 1

<script language="javascript">
function add(){
l=document.form1.slt2.options.length;
document.form1.slt2.options[l]=new Option(document.form1.slt1.options[document.form1.slt1.selectedIndex].text,document.form1.slt1.options[document.form1.slt1.selectedIndex].value);
}

Answer 2

http://fason.nease.net/samples/js/moveoptions.html