Tenth day in a row, phew... Almost missed this one, but here it is.
If you are like me, scary thought maybe, and have fallen in love with TypeScript you might be feeling that the type checking would be nice to be present even at run time. Well, I got something for you, Runtypes. With this library you can define, AND check at run time, types and more (ranges for numbers, null/undefined etc). I've for example been using it to verify the JSON-data received from REST services.
You should probably use it with a bit of caution, so your project's performance won't be suffering. But giv it a try in some small and maybe critical part.