您不会检测用户是否禁用了javascript(服务器端或客户端)。相反，你假设javascript是禁用的，并建立你的网页与javascript禁用。这消除了对noscript的需要，无论如何都应该避免使用noscript，因为它不能很好地工作，而且是不必要的。

例如，只要建立你的网站说<div id="nojs">这个网站没有JS就不能工作

然后，脚本将简单地执行document.getElementById('nojs').style。Display = 'none';并继续其正常的JS业务。

在某些情况下，倒着做就足够了。使用javascript添加一个类:

// Jquery
$('body').addClass('js-enabled');

/* CSS */
.menu-mobile {display:none;}
body.js-enabled .menu-mobile {display:block;}

这可能会在任何复杂的事情上产生维护问题，但对于某些事情来说，这是一个简单的修复。而不是试图检测它什么时候没有加载，只是根据它加载的时候样式。

在什么地方发现它?JavaScript ?那是不可能的。如果只是为了记录日志，可以使用某种跟踪方案，其中每个页面都有JavaScript，将对一个特殊资源(可能是一个非常小的gif或类似的文件)发出请求。这样，您就可以获取唯一页面请求和跟踪文件请求之间的差异。

这里是转折! 可能有客户端浏览器启用了Javascript，并且使用JS兼容的浏览器。但是不管出于什么原因Javascript在浏览器中不能工作(比如:防火墙设置)。据统计，这种情况每93个场景中就会发生1个。所以服务器检测到客户端有能力执行Javascript，但实际上并没有!

作为解决方案，我建议我们在客户端站点设置一个cookie，然后从服务器读取它。如果cookie设置好了，JS就可以正常工作。有什么想法吗?

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;
}
?>

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