Using Ext-Scripting once properly setup is straight forward. Usually it comes down to editing, reloading on the browser editing, reloading the page, .... However if you edit within a running configurations keep an eye on the console/log output. All compile errors and messages go automatically into the log.
The development cycle also can seen in the following video and in the following videos in the Users Guide.
As you can see, there is no need for any recompile anymore, no server restart everything is done dynamically, and you get instant results.