9.5 删除 cookie

• 使 cookie 过期，即可删除，原书是这么说的；

        function deleteCookie() {
            var expireDate = new Date();
            expireDate.setMonth(expireDate.getMonth() - 2);
            document.cookie = "expires=" + expireDate.toGMTString();
            console.log(document.cookie);
        }