Cookie是站点设计者放置在client的小文本文件。Cookie能为用户提供非常多的使得，比如购物站点存储用户以前浏览过的产品列表。或者门户站点记住用户喜欢选择浏览哪类新闻。 在用户同意的情况下。还能够存储用户的登录信息，使得用户在訪问站点时不必每次都键入这些信息

用法：

1.引入jquery.cookie.js

2.将cookie写入文件
[javascript] view plaincopyprint?
  1.     var COOKIE_NAME = 'username';  
  2.     if( $.cookie(COOKIE_NAME) ){  
  3.         $("#username").val(  $.cookie(COOKIE_NAME) );  
  4.     }  
  5.     $("#check").click(function(){  
  6.         if(this.checked){  
  7.             $.cookie(COOKIE_NAME, $("#username").val() , { path: '/', expires: 10 });  
  8.             //var date = new Date();  
  9.             //date.setTime(date.getTime() + (3 * 24 * 60 * 60 * 1000)); //三天后的这个时候过期  
  10.             //$.cookie(COOKIE_NAME, $("#username").val(), { path: '/', expires: date });  
  11.         }else{  
  12.             $.cookie(COOKIE_NAME, null, { path: '/' });  //删除cookie  
  13.         }  
  14.     });  
參数设置：
expires: (Number | Date)      有效期，能够设置一个整数作为有效期（单位：天），也能够设置一个日期对象作为Cookie的过期日期。假设指定日期为负数。那么此cookie将被删除；假设不设置或者设置为null，那么此cookie将被当作Session Cookie处理，而且在浏览器关闭后删除

path:  (String)   Cookie的路径属性。默认是创建该cookie的页面路径

domain: (String)   Cookie的域名属性，默认是创建该cookie的页面域名

secure: (Boolean)  假设设为true。那么此cookie的传输会要求一个安全协议。比如HTTPS

Usage

Create session cookie:

$.cookie('the_cookie', 'the_value');

Create expiring cookie, 7 days from then:

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

Create expiring cookie, valid across entire site:

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

Read cookie:

$.cookie('the_cookie'); // => "the_value" $.cookie('not_existing'); // => undefined

Read all available cookies:

$.cookie(); // => { "the_cookie": "the_value", "...remaining": "cookies" }

Delete cookie:

// Returns true when cookie was found, false when no cookie was found...$.removeCookie('the_cookie'); 
// Same path as when the cookie was written...$.removeCookie('the_cookie', { path: '/' });

Note: when deleting a cookie, you must pass the exact same path, domain and secure options that were used to set the cookie, unless you're relying on the default options that is.

Configuration

raw

By default the cookie value is encoded/decoded when writing/reading, usingencodeURIComponent/decodeURIComponent. Bypass this by setting raw to true:

$.cookie.raw = true;

json

Turn on automatic storage of JSON objects passed as the cookie value. Assumes JSON.stringify andJSON.parse:

$.cookie.json = true;

Cookie Options

Cookie attributes can be set globally by setting properties of the $.cookie.defaults object or individually for each call to $.cookie() by passing a plain object to the options argument. Per-call options override the default options.

expires

expires: 365

Define lifetime of the cookie. Value can be a Number which will be interpreted as days from time of creation or a Date object. If omitted, the cookie becomes a session cookie.

path

path: '/'

Define the path where the cookie is valid. By default the path of the cookie is the path of the page where the cookie was created (standard browser behavior). If you want to make it available for instance across the entire domain use path: '/'. Default: path of page where the cookie was created.

Note regarding Internet Explorer:

Due to an obscure bug in the underlying WinINET InternetGetCookie implementation, IE’s document.cookie will not return a cookie if it was set with a path attribute containing a filename.

(From Internet Explorer Cookie Internals (FAQ))

This means one cannot set a path using path: window.location.pathname in case such pathname contains a filename like so: /check.html (or at least, such cookie cannot be read correctly).

domain

domain: 'example.com'

Define the domain where the cookie is valid. Default: domain of page where the cookie was created.

secure

secure: true

If true, the cookie transmission requires a secure protocol (https). Default: false.

Converters

Provide a conversion function as optional last argument for reading, in order to change the cookie's value to a different representation on the fly.

Example for parsing a value into a number:

$.cookie('foo', '42'); $.cookie('foo', Number); // => 42

Dealing with cookies that have been encoded using escape (3rd party cookies):

$.cookie.raw = true; $.cookie('foo', );

You can pass an arbitrary conversion function.