jQuery cookie 插件学习

/**
 * Cookie plugin
 *
 * Copyright (c) 2006 Klaus Hartl (stilbuero.de)
 * Dual licensed under the MIT and GPL licenses:
 * http://www.opensource.org/licenses/mit-license.php
 * http://www.gnu.org/licenses/gpl.html
 *
 */

/**
 * Create a cookie with the given name and value and other optional parameters.
 *
 * @example $.cookie('the_cookie', 'the_value');
 * @desc Set the value of a cookie.

（设置一个已存在cookie的值。）
 * @example $.cookie('the_cookie', 'the_value', { expires: 7, path: '/', domain: 'jquery.com', secure: true });
 * @desc Create a cookie with all available options.

（创建一个全属性的cookie，包括保存时间，路径，域，是否使用安全的传输协议。）
 * @example $.cookie('the_cookie', 'the_value');
 * @desc Create a session cookie.

（创建一个会话cookie，浏览器关闭则会被删除。）
 * @example $.cookie('the_cookie', null);
 * @desc Delete a cookie by passing null as value. Keep in mind that you have to use the same path and domain
 *       used when the cookie was set.
 *（把value设为null即删除cookie，但是必须保证与设置时的路径，域相同。因为不同的路径或域，相同的name表示不同的cookie。）
 * @param String name The name of the cookie.
 * @param String value The value of the cookie.
 * @param Object options An object literal containing key/value pairs to provide optional cookie attributes.
 * @option Number|Date expires Either an integer specifying the expiration date from now on in days or a Date object.
 *                             If a negative value is specified (e.g. a date in the past), the cookie will be deleted.
 *                             If set to null or omitted, the cookie will be a session cookie and will not be retained
 *                             when the the browser exits.

（参数expires ：可以设置为数字（表示保存的天数），和全球标准时间 (UTC)格式的日期字符串。）
 * @option String path The value of the path atribute of the cookie (default: path of page that created the cookie).

（cookie保存的目录，默认值为保存cookie时的页面的路径。）
 * @option String domain The value of the domain attribute of the cookie (default: domain of page that created the cookie).

（cookie保存的目录，默认值为保存cookie时的页面的域。）.
 * @option Boolean secure If true, the secure attribute of the cookie will be set and the cookie transmission will
 *                        require a secure protocol (like HTTPS).

（Secure参数：Secure 为true则代表下面介绍的设置为“secure”，false则为下面介绍的设置为为空的意思。）

（Secure – 安全。指定cookie的值通过网络如何在用户和WEB服务器之间传递。这个属性的值或者是“secure”，或者为空。缺省情况下，该属性为空，也就是使用不安全的HTTP连接传递数据。如果一个 cookie 标记为secure，那么，它与WEB服务器之间就通过HTTPS或者其它安全协议传递数据。不过，设置了secure属性不代表其他人不能看到你机器本地保存的cookie。换句话说，把cookie设置为secure，只保证cookie与WEB服务器之间的数据传输过程加密，而保存在本地的cookie文件并不加密。如果想让本地cookie也加密，得自己加密数据。）

 * @type undefined
 *
 * @name $.cookie
 * @cat Plugins/Cookie
 * @author Klaus Hartl/[e-mail]
 */

/**
 * Get the value of a cookie with the given name.
 *
 * @example $.cookie('the_cookie');
 * @desc Get the value of a cookie.
 *

 （根据name获取一个cookie）
 * @param String name The name of the cookie.
 * @return The value of the cookie.
 * @type String
 *
 * @name $.cookie
 * @cat Plugins/Cookie
 * @author Klaus Hartl/[e-mail]
 */
jQuery.cookie = function(name, value, options) {
    if (typeof value != 'undefined') { // name and value given, set cookie
        options = options || {};
        if (value === null) {
            value = '';
            options = $.extend({}, options); // clone object since it's unexpected behavior if the expired property were changed
            options.expires = -1;
        }
        var expires = '';
        if (options.expires && (typeof options.expires == 'number' || options.expires.toUTCString)) {
            var date;
            if (typeof options.expires == 'number') {
                date = new Date();
                date.setTime(date.getTime() + (options.expires * 24 * 60 * 60 * 1000));
            } else {
                date = options.expires;
            }
            expires = '; expires=' + date.toUTCString(); // use expires attribute, max-age is not supported by IE
        }
        // NOTE Needed to parenthesize options.path and options.domain
        // in the following expressions, otherwise they evaluate to undefined
        // in the packed version for some reason...
        var path = options.path ? '; path=' + (options.path) : '';
        var domain = options.domain ? '; domain=' + (options.domain) : '';
        var secure = options.secure ? '; secure' : '';
        document.cookie = [name, '=', encodeURIComponent(value), expires, path, domain, secure].join('');
    } else { // only name given, get cookie
        var cookieValue = null;
        if (document.cookie && document.cookie != '') {
            var cookies = document.cookie.split(';');
            for (var i = 0; i < cookies.length; i++) {
                var cookie = jQuery.trim(cookies[i]);
                // Does this cookie string begin with the name we want?
                if (cookie.substring(0, name.length + 1) == (name + '=')) {
                    cookieValue = decodeURIComponent(cookie.substring(name.length + 1));
                    break;
                }
            }
        }
        return cookieValue;
    }
};

 

 

同名的 cookie，不同的 domain 或不同的 path，属不同的 cookie；
同名的 cookie，相同的 domain 且相同的 path，不同的 expires，属同一个 cookie。