为jquery添加cookie方法

    $.cookie = function(name, value, options) {if (typeof value != 'undefined') {
                  options = options || {};
                  if (value === null) {
                            value = '';
                            options = $.extend({}, options);
                            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();
                  }
                  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('');
                  return this;
            } else {
                  var cookieValue = null;
                  if (document.cookie && document.cookie != '') {
                            var cookies = document.cookie.split(';');
                            for (var i = 0; i < cookies.length; i++) {
                                  var cookie = cookies[i].trim();
                                  if (cookie.substring(0, name.length + 1) == (name + '=')) {
                                            cookieValue = decodeURIComponent(cookie.substring(name.length + 1));
                                            break;
                                  }
                            }
                  }
                  return cookieValue;
        }
};