javascript 对ListBox的增 删

假设有2个ListBox，ID分别为lbLeft，lbRight

选中lbLeft里的项添加到lbRight里:

 function add()
    {
        var left;
        var right;
        left = document.getElementById("lbLeft");
        right = document.getElementById("lbRight");
        for(var i=0;i<left.length;i++)
        {
            if(left.options[i].selected)
            {
                //判断该项是否已经存在
                for(j=0;j<right.length;j++)
                {
                    if(right.options[j].value==left.options[i].value)
                    {
                        return;
                    }
                }
                right.add(new Option(left.options[i].text,left.options[i].value));
            }
        }
    }

删除lbRight里的项：

    function del()
    {
        right=document.getElementById("lbRight");
        for(i=right.length-1;i>=0;i--)
        {
            if(right.options[i].selected)
            {
                right.remove(i);
            }
        }
        //重新赋值
        for(j=0;j<right.length;j++)
        {
            document.getElementById("txtAllName").value+=right.options[j].text+",";
            document.getElementById("txtAllID").value+=right.options[j].value+",";
        }
    }