javascript增加、获取和删除Cookie

/*
 *设置Cookie 
 *
 * name:cookie所对应的键
 * value:cookie所对应的值
 * expires:cookie所对应的有效时间
 * path:指定可访问cookie的路径
 * domain:指定可访问cookie的主机名
 * secure:安全性
 */
function setCookie (name,value,expires,path,domain,secure) {    
    //cookie键值对 
    var str = name + "=" + escape(value);
    //设置cookie的有效期,以小时为单位
    if(expires > 0){                               
        var date = new Date();
        var ms = expires * 3600 * 1000;
        date.setTime(date.getTime() + ms);
        str += "; expires=" + date.toGMTString();
    }
    if(path){
        str += "; path=" + path;
    }
    if(domain){
        str += "; domain=" + domain;
    }
    if(secure){
        str += "; secure";
    }
    document.cookie = str;
}
/*
 *获得Cookie 
 *
 *cookie_name:cookie的键
 */
function getCookie(cookie_name)  
{     
    var value = null;
    var allcookies = document.cookie;  
    var cookie_pos = allcookies.indexOf(cookie_name);  
    // 如果找到了索引，就代表cookie存在，  
    // 反之，就说明不存在。  
    if (cookie_pos != -1)  
    {  
        // 把cookie_pos放在值的开始，只要给值加1即可。  
        cookie_pos += cookie_name.length + 1;  
        var cookie_end = allcookies.indexOf(";", cookie_pos);  
        if (cookie_end == -1)  
        {   
            cookie_end = allcookies.length;  
        }  
        value = unescape(allcookies.substring(cookie_pos, cookie_end));  
    }  
    return value;  
} 
/*
 *删除Cookie 
 *
 *cookie_name:cookie的键
 */
function delCookie(cookie_name)
{
    var exp = new Date();
    exp.setTime(exp.getTime() - 1);
    var value = getCookie(cookie_name);
    if(value){
        document.cookie= cookie_name + "=" + value + ";expires=" + exp.toGMTString();
    }
}