How does gnome extensions website work?
ajax, gnome, javascript
Solution
It communicates with a custom "GNOME Shell Integration" browser plugin. See https://extensions.gnome.org/static/js/dbus.js for the guts.
Note that it probably won't work outside the GNOME site, for obvious security reasons.
Problem
How does http://extensions.gnome.org work? The page shows all extensions on my pc, and you can install them online with a click. How does this website can access to operating system and make changes on my shell?