By now it is probably no longer news to many: GNOME Shell moved from GJS’ own custom imports system to standard JavaScript modules (ESM).
Extensions that target older GNOME versions will not work in GNOME 45. Likewise, extensions that are adapted to work with GNOME 45 will not work in older versions.
You can still support more than one GNOME version, but you will have to upload different versions to extensions.gnome.org for pre- and post-45 support.
Please file bugs with your favorite extensions or have a friendly conversation with your extension writers so that we can help minimize the impact of this change. Ideally, you could help with the port and provide a pull or merge request to help maintainers.
The JS bindings to GTK4 (GJS) are complete, AFAIK; & allow for facilities like
Gtk.Expressionwhich the Python bindings still don’t have — & they’ve made rapid progress in a short time. The online documentation that’s available is also getting really good.Though I’m not sure why extensions have to be in JS, since JS is acting as a ‘glue language’ to the GObject bindings anyway. Isn’t an extension just a GTK application that talks to specific DBus interfaces?
I suspect that the issue boils down to not-so-well-fleshed-out (to put it politely) dbus interfaces on GTK apps. Probably GJS has an easier time setting/sending messages & signals over DBus, so that’s why extensions are in JS.
Many languages have well functioning bindings to GObject, Gdk, etc.; some are more complete than others (lua’s (lgi) are trailing behind – but still, you can do things like subscribe to a dbus_proxy in an embedded lua that lives inside vim or neovim, and send-receive messages with that) & some even come with good documentation, tutorials, etc.