Microsoft may (actually I think it will) in the future release the IE10 Chakra (JScript engine) as a stand alone module, like google V8 JavaScript Engine.
Check out what Microsoft just released regarding this topic:
http://blogs.windows.com/msedgedev/2015/05/18/using-chakra-for-scripting-applications-across-windows-10/#comment-841
Inside the blog answers you can find the latest comment from Microsoft. The answer is: "Re:Windows scripting – Windows Scripting host supports JavaScript but is not based on Chakra engine. For now, this project does not intend to change the same."