jquery.cookie.js的介绍与使用方法

什么是 cookie？

cookie 就是页面用来保存信息，比如自动登录、记住用户名等等。

cookie 的特点

1. 同个网站中所有的页面共享一套 cookie
2. cookie 有数量、大小限制
3. cookie 有过期时间jquery.cookie.js 是一款轻量级的 cookie 插件，可以读取，写入和删除 cookie。本文主要针对

jquery.cookie.js 的用法进行详细的介绍。

使用方法：

设置 cookie：

$.cookie('the_cookie', 'the_value');

注：如果 $.cookie 没有第三个参数，那么当浏览器关闭时，该 cookie 将会自动删除。

设置一个有效期为 7 天的 cookie：

$.cookie('the_cookie', 'the_value', {expires: 7});

注：$.cookie 第三个参数是一个对象，除了可以设置有效期（expires: 7），还可以设置有效路径（path: '/'）、有效域（domain: 'jquery.com'）及安全性（secure: true）。

读取 cookie：

$.cookie('the_cookie');

注：如果没有该 cookie，返回 null。

删除 cookie：

$.cookie('the_cookie', null);

我们只需要给需要删除的 cookie 设置为 null，就可以删除该 cookie。

最后附上源代码：

/**
 * 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.
 * @example $.cookie('the_cookie', 'the_value', { expires: 7, path: '/', domain: 'jquery.com', secure: true });
 * @desc Create a cookie with all available options.
 * @example $.cookie('the_cookie', 'the_value');
 * @desc Create a session cookie.
 * @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.
 *
 * @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.
 * @option String path The value of the path atribute of the cookie (default: path of page that created the cookie).
 * @option String domain The value of the domain attribute of the cookie (default: domain of page that created the cookie).
 * @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).
 * @type undefined
 *
 * @name $.cookie
 * @cat Plugins/Cookie
 * @author Klaus Hartl/klaus.hartl@stilbuero.de
 */

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

总结

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