Greasemonkey Detect

Greasemonkey 0.6.4 displays a notification bar on all URLs ending in .user.js, without checking the MIME type. If you hack your .htaccess file to serve a specific .user.js file as text/html, you can include Javascript and your browser will execute it. Greasemonkey will still display its notification bar, which can be detected by the Javascript code because it changes self.innerHeight. The rest is just details.

Click to redo the test

(Note that this only works in Firefox. The SeaMonkey version of Greasemonkey doesn't display a notification bar, so this hack doesn't work.

detect-greasemonkey.html:
<html> <head> <title>Greasemonkey Detect</title> </head> <body> <h1 id="output"></h1> <script> var output = document.getElementById('output'); var match = location.search.match(/jsheight=(\d+)/); if (match && match.length == 2) { var jsheight = match[1]; if (1*self.innerHeight == 1*jsheight) { output.innerHTML = 'Greasemonkey not detected'; } else { output.innerHTML = 'Greasemonkey detected'; } } else if (location.search) { output.innerHTML = 'Greasemonkey not detected'; } else { location.href = 'detect-greasemonkey.user.js'; } </script> </body> </html>
detect-greasemonkey.user.js:
<html> <head> <script> function detect() { location.href = 'detect-greasemonkey.html?jsheight=' + self.innerHeight; } window.onload = detect; </script> </head> <body> </body> </html>
.htaccess:
<Files detect-greasemonkey.user.js> AddType text/html .js </Files>

version 0.1 of 2006-07-11
Copyright (c) 2006, Mark Pilgrim

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