今天早上有个帖子问有多少人禁用JavaScript。然后我开始想知道可以使用什么技术来确定用户是否禁用了它。
有人知道一些简单的方法来检测JavaScript是否被禁用吗?我的意图是给一个警告，如果浏览器没有启用JS，站点将无法正常运行。
最终，我想把它们重定向到能够在没有JS的情况下工作的内容，但我需要这个检测作为一个占位符来开始。
当前回答
我过去使用的一种技术是使用JavaScript编写一个会话cookie，它只是作为一个标志，表示启用了JavaScript。然后服务器端代码查找此cookie，如果没有找到，则采取适当的操作。当然，这种技术确实依赖于启用cookie !
其他回答
noscript块在JavaScript被禁用时执行，通常用于显示你用JavaScript生成的替代内容，例如:
<script type="javascript">
... construction of ajaxy-link, setting of "js-enabled" cookie flag, etc..
</script>
<noscript>
<a href="next_page.php?nojs=1">Next Page</a>
</noscript>
没有js的用户会得到next_page链接——你可以在这里添加参数，这样你就可以在下一页知道他们是否通过js /非js链接来访问，或者试图通过js设置cookie，如果没有这些就意味着js被禁用了。这两个例子都非常琐碎，可以进行操作，但是您可以理解其中的含义。
如果你想知道有多少用户禁用了javascript，你可以这样做:
<noscript>
<img src="no_js.gif" alt="Javascript not enabled" />
</noscript>
然后检查您的访问日志，看看这个映像被击中了多少次。这是一个略显粗糙的解决方案，但它将为你的用户基础提供一个很好的百分比。
上面的方法(图像跟踪)不适用于纯文本浏览器或根本不支持js的浏览器，所以如果你的用户群主要倾向于这方面，这可能不是最好的方法。
我已经想出了另一种方法使用css和javascript本身。 这只是开始修补类和id。
CSS代码片段: 1. 创建一个css ID规则，命名为#jsDis。 2. 使用"content"属性在BODY元素后生成文本。(你可以按照自己的意愿设置样式)。 3创建第二个css ID规则，命名为#jsEn，并对其进行风格化。(为了简单起见，我给#jsEn规则设置了不同的背景色。
<style>
#jsDis:after {
content:"Javascript is Disable. Please turn it ON!";
font:bold 11px Verdana;
color:#FF0000;
}
#jsEn {
background-color:#dedede;
}
#jsEn:after {
content:"Javascript is Enable. Well Done!";
font:bold 11px Verdana;
color:#333333;
}
</style>
JavaScript代码片段: 1. 创建一个函数。 2. 使用getElementById获取BODY ID并将其分配给一个变量。 3.使用JS函数'setAttribute'，改变BODY元素ID属性的值。
<script>
function jsOn() {
var chgID = document.getElementById('jsDis');
chgID.setAttribute('id', 'jsEn');
}
</script>
HTML部分。 1. 将BODY元素属性的ID命名为#jsDis。 2. 使用函数名添加onLoad事件。(jsOn())。
<body id="jsDis" onLoad="jsOn()">
因为BODY标签的ID是#jsDis: -如果Javascript被启用，它会自己改变BODY标签的属性。 -如果Javascript是禁用的，它将显示css 'content:'规则文本。
你可以使用#包装容器，或者使用任何使用JS的DIV。 希望这有助于理解。
下面是一个PHP脚本，它可以在生成任何输出之前包含一次。它不是完美的，但在大多数情况下，它工作得足够好，以避免交付客户端不会使用的内容或代码。标题注释解释了它是如何工作的。
<?php
/*****************************************************************************
* JAVASCRIPT DETECTION *
*****************************************************************************/
// Progressive enhancement and graceful degradation are not sufficient if we
// want to avoid sending HTML or JavaScript code that won't be useful on the
// client side. A normal HTTP request will not include any explicit indicator
// that JavaScript is enabled in the client. So a "preflight response" is
// needed to prompt the client to provide an indicator in a follow-up request.
// Once the state of JavaScript availability has been received the state of
// data received in the original request must be restored before proceding.
// To the user, this handshake should be as invisible as possible.
//
// The most convenient place to store the original data is in a PHP session.
// The PHP session extension will try to use a cookie to pass the session ID
// but if cookies are not enabled it will insert it into the query string.
// This violates our preference for invisibility. When Javascript is not
// enabled the only way to effect a client side redirect is with a "meta"
// element with its "http-equiv" attribute set to "refresh". In this case
// modifying the URL is the only way to pass the session ID back.
//
// But when cookies are disabled and JavaScript is enabled then a client side
// redirect can be effected by setting the "window.onload" method to a function
// which submits a form. The form has a "method" attribute of "post" and an
// "action" attribute set to the original URL. The form contains two hidden
// input elements, one in which the session ID is stored and one in which the
// state of JavaScript availability is stored. Both values are thereby passed
// back to the server in a POST request while the URL remains unchanged. The
// follow-up request will be a POST even if the original request was a GET, but
// since the original request data is restored, the containing script ought to
// process the request as though it were a GET.
// In order to ensure that the constant SID is defined as the caller of this
// script would expect, call session_start if it hasn't already been called.
$session = isset($_SESSION);
if (!$session) session_start();
// Use a separate session for Javascript detection. Save the caller's session
// name and ID. If this is the followup request then close the caller's
// session and reopen the Javascript detection session. Otherwise, generate a
// new session ID, close the caller's session and create a new session for
// Javascript detection.
$session_name = session_name();
$session_id = session_id();
session_write_close();
session_name('JS_DETECT');
if (isset($_COOKIE['JS_DETECT'])) {
session_id($_COOKIE['JS_DETECT']);
} elseif (isset($_REQUEST['JS_DETECT'])) {
session_id($_REQUEST['JS_DETECT']);
} else {
session_id(sha1(mt_rand()));
}
session_start();
if (isset($_SESSION['_SERVER'])) {
// Preflight response already sent.
// Store the JavaScript availability status in a constant.
define('JS_ENABLED', 0+$_REQUEST['JS_ENABLED']);
// Store the cookie availability status in a constant.
define('COOKIES_ENABLED', isset($_COOKIE['JS_DETECT']));
// Expire the cookies if they exist.
setcookie('JS_DETECT', 0, time()-3600);
setcookie('JS_ENABLED', 0, time()-3600);
// Restore the original request data.
$_GET = $_SESSION['_GET'];
$_POST = $_SESSION['_POST'];
$_FILES = $_SESSION['_FILES'];
$_COOKIE = $_SESSION['_COOKIE'];
$_SERVER = $_SESSION['_SERVER'];
$_REQUEST = $_SESSION['_REQUEST'];
// Ensure that uploaded files will be deleted if they are not moved or renamed.
function unlink_uploaded_files () {
foreach (array_keys($_FILES) as $k)
if (file_exists($_FILES[$k]['tmp_name']))
unlink($_FILES[$k]['tmp_name']);
}
register_shutdown_function('unlink_uploaded_files');
// Reinitialize the superglobal.
$_SESSION = array();
// Destroy the Javascript detection session.
session_destroy();
// Reopen the caller's session.
session_name($session_name);
session_id($session_id);
if ($session) session_start();
unset($session, $session_name, $session_id, $tmp_name);
// Complete the request.
} else {
// Preflight response not sent so send it.
// To cover the case where cookies are enabled but JavaScript is disabled,
// initialize the cookie to indicate that JavaScript is disabled.
setcookie('JS_ENABLED', 0);
// Prepare the client side redirect used when JavaScript is disabled.
$content = '0; url='.$_SERVER['REQUEST_URI'];
if (!$_GET['JS_DETECT']) {
$content .= empty($_SERVER['QUERY_STRING']) ? '?' : '&';
$content .= 'JS_DETECT='.session_id();
}
// Remove request data which should only be used here.
unset($_GET['JS_DETECT'],$_GET['JS_ENABLED'],
$_POST['JS_DETECT'],$_POST['JS_ENABLED'],
$_COOKIE['JS_DETECT'],$_COOKIE['JS_ENABLED'],
$_REQUEST['JS_DETECT'],$_REQUEST['JS_ENABLED']);
// Save all remaining request data in session data.
$_SESSION['_GET'] = $_GET;
$_SESSION['_POST'] = $_POST;
$_SESSION['_FILES'] = $_FILES;
$_SESSION['_COOKIE'] = $_COOKIE;
$_SESSION['_SERVER'] = $_SERVER;
$_SESSION['_REQUEST'] = $_REQUEST;
// Rename any uploaded files so they won't be deleted by PHP. When using
// a clustered web server, upload_tmp_dir must point to shared storage.
foreach (array_keys($_FILES) as $k) {
$tmp_name = $_FILES[$k]['tmp_name'].'x';
if (move_uploaded_file($_FILES[$k]['tmp_name'], $tmp_name))
$_SESSION['_FILES'][$k]['tmp_name'] = $tmp_name;
}
// Have the client inform the server as to the status of Javascript.
?>
<!DOCTYPE html>
<html>
<head>
<script>
document.cookie = 'JS_ENABLED=1';
// location.reload causes a confirm box in FireFox
// if (document.cookie) { location.reload(true); }
if (document.cookie) { location.href = location; }
</script>
<meta http-equiv="refresh" content="<?=$content?>" />
</head>
<body>
<form id="formid" method="post" action="" >
<input type="hidden" name="<?=$session_name?>" value="<?=$session_id?>" />
<input type="hidden" name="JS_DETECT" value="<?=session_id()?>" />
<input type="hidden" name="JS_ENABLED" value="1" />
</form>
<script>
document.getElementById('formid').submit();
</script>
</body>
</html>
<?php
exit;
}
?>
noscript标记工作得很好，但是需要每个额外的页面请求来继续提供无用的JS文件，因为noscript本质上是一个客户端检查。
你可以用JS设置一个cookie，但正如其他人指出的那样，这可能会失败。理想情况下，您希望能够检测到JS客户端，并且不使用cookie，为该用户设置会话服务器端，以指示是否启用JS。
A possibility is to dynamically add a 1x1 image using JavaScript where the src attribute is actually a server side script. All this script does is saves to the current user session that JS is enabled ($_SESSION['js_enabled']). You can then output a 1x1 blank image back to the browser. The script won't run for users who have JS disabled, and hence the $_SESSION['js_enabled'] won't be set. Then for further pages served to this user, you can decide whether to include all of your external JS files, but you'll always want to include the check, since some of your users might be using the NoScript Firefox add-on or have JS disabled temporarily for some other reason.
您可能希望将此检查包含在接近页面末尾的位置，以便额外的HTTP请求不会减慢页面的呈现速度。
只是有点难，但是(发型师给了我灵感)
CSS:
.pagecontainer {
display: none;
}
JS:
function load() {
document.getElementById('noscriptmsg').style.display = "none";
document.getElementById('load').style.display = "block";
/* rest of js*/
}
HTML:
<body onload="load();">
<div class="pagecontainer" id="load">
Page loading....
</div>
<div id="noscriptmsg">
You don't have javascript enabled. Good luck with that.
</div>
</body>
在任何情况下都是可行的，对吧? 即使noscript标签不受支持(只需要一些CSS) 有人知道非CSS的解决方案吗?
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