JavaScript操作cookie的封装方法

前言：

摘自《JavaScript高级程序设计》（第3版）第631页。

记录于此，以便日后查阅

封装方法

var CookieUtil = {

    get: function (name) {
        var cookieName = encodeURIComponent(name) + '=',
            cookieStart = document.cookie.indexOf(cookieName),
            cookieValue = null;
        
        if (cookieStart > -1) {
            var 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) {    // name和value是必须，其他参数可以不设
        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) {    // 删除，name必须
        this.set(name, '', new Date(0), path, domain, secure);
    }

};