Note: After saving, you have to bypass your browser's cache to see the changes. Internet Explorer: press Ctrl-F5, Mozilla: hold down Shift while clicking Reload (or press Ctrl-Shift-R), Opera/Konqueror: press F5, Safari: hold down Shift + Alt while clicking Reload, Chrome: hold down Shift while clicking Reload.
$( function() {
	var wgNamespaceNumber = mw.config.get('wgNamespaceNumber');
	var wgTitle = mw.config.get('wgTitle');
   if(mw.config.get('wgNamespaceNumber') == 6) {
      if(wgTitle.match(/(.*)\.(jpg|jpeg)/gi)) {
          var croplink = "//tools.wmflabs.org/cropbot/cropbot.php?img="+wgTitle;
          mw.util.addPortletLink("p-tb", croplink, "Crop", "p-crop", "Crop this image", "o", false);
      }
   }
});

// [[:en:User:Lupin/popups.js]]
 
mw.loader.load(
             'https://en.wikipedia.org/w/index.php?title=User:Lupin/popups.js'
             + '&action=raw&ctype=text/javascript&dontcountme=s');