Cookie 读写类

/**
Cookie 读写类
    读：Cookie.get(name)
    写：Cookie.set(name, value, domain, ttl/*是否持久* /)
    删除: Cookie.clear(name)
    绑定Cookie变化事件 Cookie.change(function(){})
 */
var Cookie = function () {
    var prevCookie = null;
    var _user = {};
    
    jQuery(function(){
        window.setInterval(function () {
            if (!prevCookie || prevCookie != document.cookie) {
                prevCookie = document.cookie;
                jQuery(Cookie).trigger('cookie_change', prevCookie);
            }
        }, 1000);
    });

    return {
        change: function(fn){
        jQuery(this).bind('cookie_change', fn);
        },
        clear: function (name , domain) {
            var date = new Date();
            date.setTime(date.getTime() - 24 * 60 * 60 * 1000*10);
            var cookie = name + "="+Cookie.get('show_div')+"; expires=" + date.toGMTString() + "; path=/;domain=."+domain;
            document.cookie = cookie;
        },
        set: function (name, value, domain, ttl) {
            var value = value ? encodeURIComponent(typeof(value) == 'string' ? value : JSON.stringify(value)) : "";
            var expires = "";
            if (value === "") {
                ttl = -1;
            }
            if (typeof(ttl) != "undefined") {
                var date = new Date();
                date.setTime(date.getTime() + (ttl * 24 * 60 * 60 * 1000));
                expires = "; expires=" + date.toGMTString();
            }
            try {
                if (jQuery.browser.msie && value !== "") {
                    var extra = 56 + (domain||'').length;
                    var cookieByteLen = 0;
                    if (document.cookie) {
                        var cookieArr = document.cookie.split(/;\s*/);
                        cookieByteLen = cookieArr.length * extra + document.cookie.length;
                    }
                    var _302e = Cookie.get(name, false);
                    var _302f = _302e ? _302e.length : 0;
                    if ((cookieByteLen + value.length - _302f) > 4096) {
                        throw ("exceeds 4096 byte limit for cookie");
                    }
                }
                document.cookie = name + "=" + value + expires + "; path=/;" + (domain ? (" domain=." + domain) : "");
                return true;
            } catch(e) {
                return false;
            }
        },
        get: function (name, parse) {
            var cookieArr = document.cookie.split(/;\s*/);
            for (var i = 0; i < cookieArr.length; ++i) {
                var bits = cookieArr[i].split("=", 2);
                if (bits[0] == name) {
                    if (parse) {
                        try {
                            return eval("(" + decodeURIComponent(bits[1]) + ")");
                        } catch(e) {}
                    } else {
                        return decodeURIComponent(bits[1]);
                    }
                }
            }
            return null;
        }
    };
} ();