1、cookie定义:
cookie 就是页面用来保存信息,比如自动登录、记住用户名等等。
作用:
- 同个网站中所有的页面共享一套 cookie
- cookie 有数量、大小限制
- cookie 有过期时间
3、cookie的使用方法:
通过 document.cookie 来写入 cookie
<!DOCTYPE HTML>
<html lang="en-US">
<head>
<meta charset="UTF-8">
<title>cookie基础</title>
</head>
<body>
</body>
</html>
<script type="text/javascript">
document.cookie = 'username=abc';
document.cookie = 'password=123';
document.cookie = 'email=abcdef@123.com';
</script>
打开浏览器查看 cookie,可以发现新定义的 cookie 并不会将原来的覆盖。
如果没有设置过期时间,那么关闭浏览器就会清空 cookie。如何设置过期时间呢?答案是:expires。一般我们会结合 Date 对象来使用。
var d = new Date();
d.setTime(d.getTime() + 1 * 3600 * 1000);
document.cookie = 'username=abc; expires=' + d.toGMTString();
我们可以通过火狐浏览器看到,username 的过期时间是当前时间的 1 小时后。
最后对获取 cookie 的方法进行封装:
function setCookie(name,value,hours){
var d = new Date();
d.setTime(d.getTime() + hours * 3600 * 1000);
document.cookie = name + '=' + value + '; expires=' + d.toGMTString();
}
学会了如何设置 cookie,那么该如何读取 cookie 呢?
首先我们看下 cookie 里的内容是什么类型?
document.cookie = 'username=abc';
document.cookie = 'password=123';
document.cookie = 'email=abcdef@123.com';
typeof document.cookie; //string
alert(document.cookie); //'username=abc; password=123; email=abcdef@123.com'
得到的是一串字符串,需要注意的是,每个 ; 后面都有个空格。
那么我们如何取到具体的数值呢?附上代码:
function getCookie(name){
var arr = document.cookie.split('; ');
for(var i = 0; i < arr.length; i++){
var temp = arr[i].split('=');
if(temp[0] == name){
return temp[1];
}
}
return '';
}
除了设置、获取 cookie,我们还可以删除 cookie。我们在网上经常看到有清除用户名这样的功能,其实就是用到了清除 cookie。
清除 cookie 其实很简单,只要使过期时间为过去时间就可以了。
function removeCookie(name){
var d = new Date();
d.setTime(d.getTime() - 10000);
document.cookie = name + '=1; expires=' + d.toGMTString();
}
最后我们将设置、获取、清除 cookie 封装成一个 cookie.js
function setCookie(name,value,hours){
var d = new Date();
d.setTime(d.getTime() + hours * 3600 * 1000);
document.cookie = name + '=' + value + '; expires=' + d.toGMTString();
}
function getCookie(name){
var arr = document.cookie.split('; ');
for(var i = 0; i < arr.length; i++){
var temp = arr[i].split('=');
if(temp[0] == name){
return temp[1];
}
}
return '';
}
function removeCookie(name){
var d = new Date();
d.setTime(d.getTime() - 10000);
document.cookie = name + '=1; expires=' + d.toGMTString();
}
jquery.cookie.js 的使用指南
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)。
设置一个持久并带有效路径的cookie:
$.cookie(‘cookieName’,'cookieValue’,{expires:7,path:’/'});
注:如果不设置有效路径,在默认情况下,只能在cookie设置当前页面读取该cookie,cookie的路径用于设置能够读取cookie的顶级目录。
创建一个持久并带有效路径和域名的cookie:
$.cookie(‘cookieName’,'cookieValue’,{expires:7,path:’/',domain: ‘chuhoo.com’,secure: false,raw:false});
注:domain:创建cookie所在网页所拥有的域名;secure:默认是false,如果为true,cookie的传输协议需为https;raw:默认为false,读取和写入时候自动进行编码和解码(使用encodeURIComponent编码,使用decodeURIComponent解码),关闭这个功能,请设置为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;
}
};