My JS Application, as the name suggests, is nothing but an application written in JS. It installs, and it runs. It's meant as an example of the GNOME application platform, and in particular Gtk and the Gjs package system.
It should also work as a template for developing a real application, ie. one that does something, without spending all the time doing build system configuration.
My JS Application most of the familiar UI you'd expect from a core application: it has a main window with a header bar, it has a search bar and it has multiple page stack.
On the developer side, the most prominent feature is that My JS Application runs uninstalled with a special Meson target. You should be able to run
meson _build
meson compile -C _build devel
and everything should just work, without having to run ninja install.
Also, it features an util module, which deals with GtkBuilder and GtkCssProvider, again providing transparency between the installed and not installed cases.
The package is under a 3-clause BSD license, to make it suitable for inclusion in any application.