📄 js_cookies.asp
字号:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html lang="en-US" xml:lang="en-US" xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>JavaScript Cookies</title>
<link rel="shortcut icon" href="../favicon.ico" type="image/x-icon" />
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1" />
<meta name="Keywords" content="xml,tutorial,html,dhtml,css,xsl,xhtml,javascript,asp,ado,vbscript,dom,sql,colors,soap,php,authoring,programming,training,learning,beginner's guide,primer,lessons,school,howto,reference,examples,samples,source code,tags,demos,tips,links,FAQ,tag list,forms,frames,color table,w3c,cascading style sheets,active server pages,dynamic html,internet,database,development,Web building,Webmaster,html guide" />
<meta name="Description" content="Free HTML XHTML CSS JavaScript DHTML XML DOM XSL XSLT RSS AJAX ASP ADO PHP SQL tutorials, references, examples for web building." />
<meta http-equiv="pragma" content="no-cache" />
<meta http-equiv="cache-control" content="no-cache" />
<link rel="stylesheet" type="text/css" href="../stdtheme.css" />
<script type="text/javascript">
var gaJsHost = (("https:" == document.location.protocol) ? "../../https@ssl./default.htm" : "../../www./default.htm");
document.write(unescape("%3Cscript src='" + gaJsHost + "google-analytics.com/ga.js' type='text/javascript'%3E%3C/script%3E"));
</script>
<script type="text/javascript">
var pageTracker = _gat._getTracker("UA-3855518-1");
pageTracker._initData();
pageTracker._trackPageview();
</script>
</head>
<body>
<a name="top"></a>
<table cellpadding="0" cellspacing="0" width="100%" bgcolor="#808080">
<tr>
<td width="234" valign="top">
<a href="../default.htm"><img src="../images/w3default80.jpg" border="0" alt="W3Schools" /></a>
</td>
<th valign="middle" align="left" class="right">
<script type="text/javascript"><!--
google_ad_client = "pub-3440800076797949";
/*txtimg*/
google_ad_slot = "5330033957";
google_ad_width = 728;
google_ad_height = 90;
//-->
</script>
<script type="text/javascript" src="../../pagead2.googlesyndication.com/pagead/show_ads.js">
</script>
<noscript>
<a href="../default.asp" target="_blank"><img src="../banners/w6.gif" border="0" alt="W3Schools" /></a>
</noscript>
<br /></th>
</tr>
</table>
<table style="margin-left:1px" width="800px" border="0" cellpadding="0" cellspacing="2">
<tr>
<td width="137" class="content" valign="top"><br />
<a class="left" href="../default.asp" target="_top">
<img src="../images/homeicon.gif" border="0" alt="home" /></a>
<a class="left" href="../default.asp" target="_top">
<b>HOME</b></a>
<br /><br />
<b>JS Basic</b>
<br />
<a class="left" target="_top" href="default.asp" >JS HOME</a><br />
<a class="left" target="_top" href="js_intro.asp" >JS Introduction</a><br />
<a class="left" target="_top" href="js_howto.asp" >JS How To</a><br />
<a class="left" target="_top" href="js_whereto.asp" >JS Where To</a><br />
<a class="left" target="_top" href="js_statements.asp" >JS Statements</a><br />
<a class="left" target="_top" href="js_comments.asp" >JS Comments</a><br />
<a class="left" target="_top" href="js_variables.asp" >JS Variables</a><br />
<a class="left" target="_top" href="js_operators.asp" >JS Operators</a><br />
<a class="left" target="_top" href="js_comparisons.asp" >JS Comparisons</a><br />
<a class="left" target="_top" href="js_if_else.asp" >JS If...Else</a><br />
<a class="left" target="_top" href="js_switch.asp" >JS Switch</a><br />
<a class="left" target="_top" href="js_popup.asp" >JS Popup Boxes</a><br />
<a class="left" target="_top" href="js_functions.asp" >JS Functions</a><br />
<a class="left" target="_top" href="js_loop_for.asp" >JS For Loop</a><br />
<a class="left" target="_top" href="js_loop_while.asp" >JS While Loop</a><br />
<a class="left" target="_top" href="js_break.asp" >JS Break Loops</a><br />
<a class="left" target="_top" href="js_loop_for_in.asp" >JS For...In</a><br />
<a class="left" target="_top" href="js_events.asp" >JS Events</a><br />
<a class="left" target="_top" href="js_try_catch.asp" >JS Try...Catch</a><br />
<a class="left" target="_top" href="js_throw.asp" >JS Throw</a><br />
<a class="left" target="_top" href="js_onerror.asp" >JS onerror</a><br />
<a class="left" target="_top" href="js_special_characters.asp" >JS Special Text</a><br />
<a class="left" target="_top" href="js_guidelines.asp" >JS Guidelines</a><br />
<br />
<b>JS Objects</b>
<br />
<a class="left" target="_top" href="js_obj_intro.asp" >JS Objects Intro</a><br />
<a class="left" target="_top" href="js_obj_string.asp" >JS String</a><br />
<a class="left" target="_top" href="js_obj_date.asp" >JS Date</a><br />
<a class="left" target="_top" href="js_obj_array.asp" >JS Array</a><br />
<a class="left" target="_top" href="js_obj_boolean.asp" >JS Boolean</a><br />
<a class="left" target="_top" href="js_obj_math.asp" >JS Math</a><br />
<a class="left" target="_top" href="js_obj_regexp.asp" >JS RegExp</a><br />
<a class="left" target="_top" href="js_obj_htmldom.asp" >JS HTML DOM</a><br />
<br />
<b>JS Advanced</b>
<br />
<a class="left" target="_top" href="js_browser.asp" >JS Browser</a><br />
<a class="left" target="_top" href="js_cookies.asp" style='font-weight:bold;'>JS Cookies</a><br />
<a class="left" target="_top" href="js_form_validation.asp" >JS Validation</a><br />
<a class="left" target="_top" href="js_animation.asp" >JS Animation</a><br />
<a class="left" target="_top" href="js_image_maps.asp" >JS Image Maps</a><br />
<a class="left" target="_top" href="js_timing.asp" >JS Timing</a><br />
<a class="left" target="_top" href="js_objects.asp" >JS Create Object</a><br />
<a class="left" target="_top" href="js_summary.asp" >JS Summary</a><br />
<br />
<b>Examples/Quiz</b>
<br />
<a class="left" target="_top" href="js_examples.asp" >JS Examples</a><br />
<a class="left" target="_top" href="js_examples_2.asp" >JS Object Examples</a><br />
<a class="left" target="_top" href="js_examples_3.asp" >JS DOM Examples</a><br />
<a class="left" target="_top" href="js_quiz.asp" >JS Quiz</a><br />
<br />
<b>JS References</b>
<br />
<a class="left" target="_top" href="../jsref/default.asp" >JS Objects</a><br />
<a class="left" target="_top" href="../htmldom/dom_reference.asp" >JS HTML DOM</a><br />
<br />
<b>Selected Reading</b><br />
<a class="left" target="_top" href="../browsers/browsers_stats.asp">Web Statistics</a><br />
<a class="left" target="_top" href="../site/site_glossary.asp">Web Glossary</a><br />
<a class="left" target="_top" href="../hosting/default.asp">Web Hosting</a><br />
<a class="left" target="_top" href="../quality/default.asp">Web Quality</a><br /><br />
<a class="left" target="_top" href="../forum/default.asp">W3Schools Forum</a><br /><br />
<a class="left" target="_top" href="../about/about_helping.asp">Helping W3Schools</a><br /><br />
<script type="text/javascript"><!--
google_ad_client = "pub-3440800076797949";
/*LeftLinkUnit*/
google_ad_slot = "4854527104";
google_ad_width = 120;
google_ad_height = 90;
//-->
</script>
<script type="text/javascript"
src="../../pagead2.googlesyndication.com/pagead/show_ads.js">
</script>
</td>
<td valign="top">
<table style="border: 1px solid gray" width="100%" bgcolor="#FFFFFF" border="0" cellpadding="5" cellspacing="0">
<tr>
<td>
<h1>JavaScript Cookies</h1>
<a href="js_browser.asp"><img alt="previous" border="0" src="../images/btn_previous.gif" width="100" height="20" /></a>
<a href="js_form_validation.asp"><img alt="next" border="0" src="../images/btn_next.gif" width="100" height="20" /></a>
<hr />
<p class="intro">A cookie is often used to identify a user.</p>
<hr />
<h2>Examples</h2>
<p><a target="_blank" href="tryit.asp@filename=tryjs_cookie_username">Create a welcome cookie</a></p>
<hr />
<h2>What is a Cookie? </h2>
<p>A cookie is a variable that is stored on the visitor's computer. Each
time the same computer requests a page with a browser, it will send the cookie
too. With JavaScript, you can both create and retrieve cookie values.</p>
<p>Examples of cookies:</p>
<ul>
<li>Name cookie - The first time a visitor arrives to your web page, he or
she must fill in her/his name. The name is then stored in a cookie. Next
time the visitor arrives at your page, he or she could get a welcome message
like "Welcome John Doe!" The name is retrieved from the stored cookie</li>
<li>Password cookie - The first time a visitor arrives to your web page, he
or she must fill in a password. The password is then stored in a cookie.
Next time the visitor arrives at your page, the password is retrieved from
the cookie</li>
<li>Date cookie - The first time a visitor arrives to your web page, the
current date is stored in a cookie. Next time the visitor arrives at your
page, he or she could get a message like "Your last visit was on Tuesday
August 11, 2005!" The date is retrieved from the stored cookie</li>
</ul>
<hr />
<h2>Create and Store a Cookie</h2>
<p>In this example we will create a cookie that stores the name of a visitor.
The first time a visitor arrives to the web page, he or she will be asked to
fill in her/his name. The name is then stored in a cookie. The next time the
visitor arrives at the same page, he or she will get welcome message.</p>
<p>First, we create a function that stores the name of the visitor in a cookie
variable:</p>
<table class="ex" cellspacing="0" border="1" width="100%" id="table3"><tr><td>
<pre>function setCookie(c_name,value,expiredays)
{<br />var exdate=new Date();<br />exdate.setDate(exdate.getDate()+expiredays);
document.cookie=c_name+ "=" +escape(value)+
((expiredays==null) ? "" : ";expires="+exdate.toGMTString());
}</pre>
</td></tr></table>
<p>The parameters of the function above hold the name of the cookie, the value
of the cookie, and the number of days until the cookie expires.</p>
<p>In the function above we first convert the number of days to a valid date,
then we add the number of days until the cookie should expire.
After that we store the cookie name, cookie value and the expiration date in the document.cookie object.</p>
<p>Then, we create another function that checks if the cookie has been set:</p>
<table class="ex" cellspacing="0" border="1" width="100%" id="table4"><tr><td>
<pre>function getCookie(c_name)
{
if (document.cookie.length>0)
{
c_start=document.cookie.indexOf(c_name + "=");
if (c_start!=-1)
{
c_start=c_start + c_name.length+1;
c_end=document.cookie.indexOf(";",c_start);
if (c_end==-1) c_end=document.cookie.length;
return unescape(document.cookie.substring(c_start,c_end));
}
}
return "";
}</pre>
</td></tr></table>
<p>The function above first checks if a cookie is stored at all in the
document.cookie object. If the document.cookie object holds some cookies, then
check to see if our specific cookie is stored. If our cookie is found, then
return the value, if not - return an empty string.</p>
<p>Last, we create the function that displays a welcome message if the cookie is
set, and if the cookie is not set it will display a prompt box, asking for the
name of the user:</p>
<table class="ex" cellspacing="0" border="1" width="100%" id="table5"><tr><td>
<pre>function checkCookie()
{
username=getCookie('username');
if (username!=null && username!="")
{
alert('Welcome again '+username+'!');
⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -