I have learned how to code html, javascript, and css to make simple games (not published but completed). I want to make better games so I have decided to use a game engine. I have an issue with my computer that stops me using unity but I still want to program in javascript or javascript like languages such as UnityScript. The other major game engine that I frequently see is unreal4 but that is c++ only and I don't want to learn a new language.
Can someone please suggest an alternative on the same standard to the mentioned languages that uses Javascript. Also is unreal.js for unreal 4 any good.