The Sciter engine currently uses TIScript - a language c-smile orginally developed and the kickstarter proposal is to open source Sciter as is, then replace TIScript with the QuickJS engine. (TIScript is a very nice scripting language in itself that is easily picked up by JS devs)
The standard C version of QuickJS can be compiled using visual studio on windows as can be seen in this repo: https://github.com/c-smile/quickjspp
(Edit to update to latest repo)
QuickJS seems interesting, but I couldn't manage to compile it on Windows (without MSYS2).
That said - having used Duktape in production, it's a very handy little library. Small, easy to drop into projects, great way to add support for custom user scripts or to run js code somewhere outside of a browser context.
Also - insanely easy to target still, despite the lack of ES6+, as long as you already have babel somewhere in your build pipeline.