<%@ Page Language="C#" AutoEventWireup="true" CodeFile="test.aspx.cs" Inherits="test_test" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
<title></title>
<script language="javascript" type="text/javascript">
function goLeft(){
for (var i = 0; i <document.form1.s1.length; i++) {
if (document.form1.s1.options[i].selected == true) {
var sign=false;
for(j=0;j<document.form1.s2.length;j++){
//alert(document.form1.s1.options[i].value+"=================="+document.form1.s2.options[j].value);
if(document.form1.s1.options[i].value==document.form1.s2.options[j].value){
sign=true;
}
}
if(sign==false){
alert(document.form1.s1.value);
myoption = new Option(document.form1.s1.options[i].value);
document.form1.s2.options.add(myoption);
}
}
}
}
function goRight(){
for (var i = 0; i <document.form1.s2.length; i++) {
if (document.form1.s2.options[i].selected == true) {
document.form1.s2.remove(i);
}
}
}
</script>
</head>
<body>
<form name="form1" id="form1" action="">
<table>
<tr>
<td>
<select name="s1" id="s1" MULTIPLE >
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
<option value="4">4</option>
</select>
</td>
<td>
<input type="button" value=">>" onclick="goLeft()">
<br>
<input type="button" value="<<" onclick="goRight()">
</td>
<td>
<select name="s2" id="s2" MULTIPLE>
</select>
</td>
</form>
</body>
</html>