js操作ListBox实现多项的添加和删除

//添加多个项到另一个ListBox中去   
function add(res,sel){   
            var objres=document.getElementById(res);   
            var objsel=document.getElementById(sel);   
            var customOptions;   
            for(var i=0;i<objres.options.length;i++)   
            {   
                if(objres.options[i].selected)   
                {   
                    customOptions = document.createElement("OPTION");   
                    customOptions.text=objres.options[i].text.replace(/├/g,"").replace(/　/g,"");   
                    customOptions.value=objres.options[i].value;   
                    objsel.add(customOptions,0);   
                }   
            }   
            return false;   
}  

 

 

//删除多个   
function del(dels){   
    var objdel=document.getElementById(dels);   
    for(var i=objdel.options.length-1;i>=0;i--)   
    {   
        if(objdel.options[i].selected)   
        {   
            objdel.remove(i);   
        }   
    }   
}