javascript操作listbox方法

function SelectAll()
        {
            var lst1=window.document.getElementById("SourceListBox");
            var length = lst1.options.length;
            for(var i=0;i<length;i++)
            {
                var v = lst1.options[i].value;
                var t = lst1.options[i].text;
                var lst2=window.document.getElementById("DestinationListBox");
                lst2.options[i] = new Option(t,v,true,true);   
            }
           
        }
       
        function DelAll()
        {
            var lst2=window.document.getElementById("DestinationListBox");
            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 lst1=window.document.getElementById("SourceListBox");
            var lstindex=lst1.selectedIndex;
            if(lstindex<0)
                return;
            var v = lst1.options[lstindex].value;
            var t = lst1.options[lstindex].text;
            var lst2=window.document.getElementById("DestinationListBox");
            lst2.options[lst2.options.length] = new Option(t,v,true,true);   
               
        }
       
        function DelOne()
        {
            var lst2=window.document.getElementById("DestinationListBox");
            var lstindex=lst2.selectedIndex;
            if(lstindex>=0)
            {
                var v = lst2.options[lstindex].value+";";
                lst2.options[lstindex].parentNode.removeChild(lst2.options[lstindex]);
            }
               
        }