cookie的设置和获取

function setCookie(c_name, value, expiredays) {
        var exdate = new Date();
        exdate.setDate(exdate.getDate() + expiredays);
        document.cookie = c_name + "=" + escape(value) + ((!expiredays) ? "" : ";expires=" + exdate.toGMTString());
    }

expiredays：不传是默认关闭浏览器失效

   function getCookie(c_name) {
        if (document.cookie.length > 0) {
            var c_start = document.cookie.indexOf(c_name + "=");
            if (c_start != -1) {
                c_start = c_start + c_name.length + 1;
                var c_end = document.cookie.indexOf(";", c_start);
                if (c_end == -1)
                    c_end = document.cookie.length;
                return unescape(document.cookie.substring(c_start, c_end));
            }
        }
        return "";
    }