function setCookie(name,value,days) //三个参数，一个是cookie的名字，一个是值，一个是保存的天数
{
    var exp  = new Date();
    exp.setTime(exp.getTime() + days*24*60*60*1000);
    document.cookie = name + "="+ escape (value) + ";expires=" + exp.toGMTString();
}

function getCookie(name) //取cookies函数        
{
    var arr = document.cookie.match(new RegExp("(^| )"+name+"=([^;]*)(;|$)"));
     if(arr != null) return unescape(arr[2]); return null;

}

function delCookie(name) //删除cookie
{
    var exp = new Date();
    exp.setTime(exp.getTime() - 1);
    var cval=getCookie(name);
    if(cval!=null) document.cookie= name + "=" + cval + ";expires=" + exp.toGMTString();
}