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
将此添加到每页的HEAD标记。
<noscript>
<meta http-equiv="refresh" runat="server" id="mtaJSCheck" content="0;logon.aspx" />
</noscript>
所以你有:
<head>
<noscript>
<meta http-equiv="refresh" runat="server" id="mtaJSCheck" content="0;logon.aspx" />
</noscript>
</head>
感谢杰。
其他回答
也许听起来很奇怪，但你可以试一试:
<?php $jsEnabledVar = 0; ?>
<script type="text/javascript">
var jsenabled = 1;
if(jsenabled == 1)
{
<?php $jsEnabledVar = 1; ?>
}
</script>
<noscript>
var jsenabled = 0;
if(jsenabled == 0)
{
<?php $jsEnabledVar = 0; ?>
}
</noscript>
现在在整个页面中使用'$jsEnabledVar'的值。你也可以用它来显示一个块，告诉用户JS被关闭了。
希望这能有所帮助
将此添加到每页的HEAD标记。
<noscript>
<meta http-equiv="refresh" runat="server" id="mtaJSCheck" content="0;logon.aspx" />
</noscript>
所以你有:
<head>
<noscript>
<meta http-equiv="refresh" runat="server" id="mtaJSCheck" content="0;logon.aspx" />
</noscript>
</head>
感谢杰。
对于那些只想跟踪js是否被启用的人，如何使用ajax例程来存储状态?例如，我将所有访问者/访问记录在一组表中。JSenabled字段可以设置为默认值FALSE，如果启用了JS, ajax例程会将其设置为TRUE。
您会想看一下noscript标记。
<script type="text/javascript">
...some javascript script to insert data...
</script>
<noscript>
<p>Access the <a href="http://someplace.com/data">data.</a></p>
</noscript>
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;
}
?>
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