/*使用方法如下:
设置cookie的名值对
$.cookie(’name’, ‘value’);
设置cookie的名值对，有效期，路径，域，安全
$.cookie(’name’, ‘value’, {expires: 7, path: ‘/’, domain: ‘jquery.com’, secure: true});
新建一个cookie 包括有效期 路径 域名等
读取cookie的值
var account= $.cookie('name');
删除一个cookie
example $.cookie(’name’, null);*/

jQuery.cookie = function(name, value, options) {
   if (typeof value != 'undefined') { // name and value given, set cookie
   options = options || {};
   if (value === null) 
   {
       value = '';
       options.expires = -1;
   }
   var expires = '';
   if (options.expires && (typeof options.expires == 'number' || options.expires.toUTCString)) 
   {
        var date;
       if (typeof options.expires == 'number') 
       {
       date = new Date();
       date.setTime(date.getTime() + (options.expires * 24 * 60 * 60 * 1000));
       } 
       else 
       {
       date = options.expires;       
       }
       expires = '; expires=' + date.toUTCString(); // use expires attribute, max-age is not supported by IE
   }
   var path = options.path ? '; path=' + options.path : '';
   var domain = options.domain ? '; domain=' + options.domain : '';
   var secure = options.secure ? '; secure' : '';
   document.cookie = [name, '=', encodeURIComponent(value), expires, path, domain, secure].join('');
   } 
   else 
   { // only name given, get cookie
       var cookieValue = null;
       if (document.cookie && document.cookie != '') 
       {
           var cookies = document.cookie.split(';');
           for (var i = 0; i < cookies.length; i++) 
           {
           var cookie = jQuery.trim(cookies[i]);
           // Does this cookie string begin with the name we want?
           if (cookie.substring(0, name.length + 1) == (name + '=')) 
           {
           cookieValue = decodeURIComponent(cookie.substring(name.length + 1));
           break;
           }
       }
   }
   return cookieValue;
   }
};