cookie操作（jquery的cookie插件源码）

cookie : function (key, value, options) {
            var days, time, result, decode;

            // A key and value were given. Set cookie.
            if (arguments.length > 1 && String(value) !== "[object Object]") {
                // Enforce object
                options = extend({}, options);

                if (value === null || value === undefined){ options.expires = -1; }

                if (typeof options.expires === 'number') {
                    days = (options.expires * 24 * 60 * 60 * 1000);
                    time = options.expires = new Date();

                    time.setTime(time.getTime() + days);
                }

                value = String(value);

                return (document.cookie = [
                    encodeURIComponent(key), '=',
                    options.raw ? value : encodeURIComponent(value),
                    options.expires ? '; expires=' + options.expires.toUTCString() : '',
                    options.path ? '; path=' + options.path : '',
                    options.domain ? '; domain=' + options.domain : '',
                    options.secure ? '; secure' : ''
                ].join(''));
            }

            // Key and possibly options given, get cookie
            options = value || {};

            decode = options.raw ? function (s) { return s } : decodeURIComponent;

            return (result = new RegExp('(?:^|; )' + encodeURIComponent(key) + '=([^;]*)').exec(document.cookie)) ? decode(result[1]) : null;
        },