js操作listbox

　

<script type="text/javascript">
        function SelectAll()
        {
            var lst1=window.document.getElementById("<%=lb_Sourse.ClientID %>");
            var length = lst1.options.length;
             var string = window.document.getElementById("<%=hf_NewName.ClientID %>")
            for(var i=0;i<length;i++)
            {
                var v = lst1.options[i].value;
                var t = lst1.options[i].text;            
                var lst2=window.document.getElementById("<%=lb_NewName.ClientID %>");
                lst2.options[i] = new Option(t,v,true,true);
                string.value+=v;
            }
        }
       
        function DelAll()
        {
            var lst2=window.document.getElementById("<%=lb_NewName.ClientID %>");
            var length = lst2.options.length;
            for(var i=length;i>0;i--)
            {
                lst2.options[i-1].parentNode.removeChild(lst2.options[i-1]);
            }
        }
       
        function SelectOne()
        {
          var string = window.document.getElementById("<%=hf_NewName.ClientID %>")
            var lst1=window.document.getElementById("<%=lb_Sourse.ClientID %>");
            var lst2=window.document.getElementById("<%=lb_NewName.ClientID %>");
            var lstindex=lst1.selectedIndex;
            var length = lst2.options.length;
            var isExists = false;
            if(lstindex<0)
                return;
            else if(length != null)
            {
                for(var i=0;i < length; i++)
                {
                     if(lst2.options[i].text == lst1[lstindex].text&&lst2.options[i].value == lst1[lstindex].value)
                     {
                        isExists = true;
                     }
                }
            }
            else
            {
                return;
            }
            if (isExists == false)
            {
                var v = lst1.options[lstindex].value;
                var t = lst1.options[lstindex].text;
                lst2.options[lst2.options.length] = new Option(t,v,true,true);
                string.value+=v;
            }
            else
            {
                alert("所选条目已经存在");
                return false;
            }
        }
       
        function DelOne()
        {
            var lst2=window.document.getElementById("<%=lb_NewName.ClientID %>");
            var lstindex=lst2.selectedIndex;
            if(lstindex>=0)
            {
                var v = lst2.options[lstindex].value+";";
                lst2.options[lstindex].parentNode.removeChild(lst2.options[lstindex]);
            }
        }
</script>