title: How is the relationship between a typescript (.ts) and its javascript (.js) maintained?
body: <p>I have a typescript project working fine. I created a second project and copy some of my previous code via the file system. Everything works fine with the exception of the fact that my .js is now not in sync with my .ts.
     I now how to solve the problem: removing both files and copy the again using Visual Studio interface by dragging the ts file (that will carry the .js automatically)
     Anyway, I got curious and now I want to know, how is the .ts and the .js know each other?.
     In ASP.NET you have the notion of code behind., but here I do not see how this done.
     is Visual Studio keeping the relationship in the a hidden file?</p>