function createCookie(name,value,days) 
{
if (days) 
{
var date = new Date();
date.setTime(date.getTime()+(days*24*60*60*1000));
var expires = "; expires="+date.toGMTString(); //将日期格式转换成GMT格式
}
else{
 expires = ""; 
 }
document.cookie = name+"="+value+expires+"; path=/"; //将cookie内容写入客户端
}
//javascript实现cookies的读取
function getCookie(name) 
{
var nameEQ = name + "=";
var ca = document.cookie.split(';'); //将各个 cookie 分隔开，并存为数组
for(var i=0;i < ca.length;i++) 
{
var c = ca[i];
while (c.charAt(0)==' ') c = c.substring(1,c.length);
if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length,c.length);
}
return null;
}
//javascript实现cookies的删除
function delCookie(name)
{ var exp = new Date();
    exp.setTime(exp.getTime() - 1);
    var cval=getCookie(name);
    if(cval!=null) document.cookie= name + "="+cval+";expires="+exp.toGMTString();
}
function addCookie(objName,objValue,objHours){//添加cookie
   var str = objName + "=" + escape(objValue);
   if(objHours > 0){//为0时不设定过期时间，浏览器关闭时cookie自动消失
    var date = new Date();
    var ms = objHours*3600*1000;
    date.setTime(date.getTime() + ms);
    str += "; expires=" + date.toGMTString();
   }
   document.cookie = str;
   alert("添加cookie成功");
  }