cookie的那些事

前言：先写确定的两条

1.cookie的作用域 domain当且仅当能够设置为当前域名/ 父域名 。

2.想要获取能够使用的cookie使用document.cookie查看，通过控制台Application下查看cookie有时不够准确。

3.想要将顶级域名下的cookie让其所有子域名都能获取，如有 nao100.com、yannaoqi100.com、yan.naoqi100.com，

那么只需在nao100.com域名下设置cookie的domain为 .nao100.com

4.对cookie几个方法的封装

var CookieUtil = {

    get: function (name) {
        var cookieName = encodeURIComponent(name) + "=",
            cookieStart = document.cookie.indexOf(cookieName),
            cookieValue = null,
            cookieEnd;

        if (cookieStart > -1) {
            cookieEnd = document.cookie.indexOf(";", cookieStart);
            if (cookieEnd == -1) {
                cookieEnd = document.cookie.length;
            }
            cookieValue = decodeURIComponent(document.cookie.substring(cookieStart + cookieName.length, cookieEnd));
        }

        return cookieValue;
    },

    set: function (name, value, expires, path, domain, secure) {
        var cookieText = encodeURIComponent(name) + "=" + encodeURIComponent(value);

        if (expires instanceof Date) {
            cookieText += "; expires=" + expires.toGMTString();
        }

        if (path) {
            cookieText += "; path=" + path;
        }

        if (domain) {
            cookieText += "; domain=" + domain;
        }

        if (secure) {
            cookieText += "; secure";
        }

        document.cookie = cookieText;
    },

    unset: function (name, path, domain, secure) {
        this.set(name, "", new Date(0), path, domain, secure);
    }
};