You can build an Windows desktop app with JavaScript, TypeScript, CoffeeScript, ReScript, and HTML/CSS on Windows built-in ECMAScript engine. This framework uses the JavaScript engine built into the Windows OS, allowing you to create complete applications with just a text editor. You can implement most Windows system features with JavaScript, including GUI applications, console applications, office automation applications, and even Windows Service applications. Additionally, you can use transpiler languages like TypeScript, Rescript, CoffeeScript 2, and LiveScript for Windows system programming!