2)创建

Cookie.setCookie=function(name,value,option){
     //用于存储赋值给document.cookie的cookie格式字符串
     var str=name+"="+escape(value);  
     if(option){
            //如果设置了过期时间
            if(option.expireDays){
                   var date=new Date();
                   var ms=option.expireDays*24*3600*1000;
                   date.setTime(date.getTime()+ms);
                   str+="; expires="+date.toGMTString();
            } 
            if(option.path)str+="; path="+path;         //设置访问路径
            if(option.domain)str+="; domain"+domain;    //设置访问主机
            if(option.secure)str+="; true";             //设置安全性
     }
     document.cookie=str;
}

Cookie.getCookie=function(name){
     var cookieArray=document.cookie.split("; "); //得到分割的cookie名值对
     var cookie=new Object();
     for(var i=0;i<cookieArray.length;i++){
           var arr=cookieArray[i].split("=");    //将名和值分开
           if(arr[0]==name)return unescape(arr[1]); //如果是指定的cookie，则返回它的值
     }
     return "";
}

Cookie.deleteCookie=function(name){
     this.setCookie(name,"",{expireDays:-1}); //将过期时间设置为过去来删除一个cookie
}

var Cookie={
      setCookie:function(){},
      getCookie:function(){},
      deleteCookie:function(){}
}

Cookie.setCookie("user","jack");
alert(Cookie.getCookie("user"));
Cookie.deleteCookie("user");
alert(Cookie.getCookie("user"));