None of those languages AFAIK (I don't really know C#) will allow you to call a constructor function as anything except a constructor function and constructor functions are always constructors and therefor will always return a new object.

Javascript in it's infinite wisdom will allow one to use any function as a constructor or not. So code the should be obviously wrong will not generate an error or even a warning, this is not something you want from a language. Since we can't change JS , there is merit to the argument that you should change your own code to avoid even possibly having this problem.

Arguments made on the basis of "this is a mistake I am unlikely to make" fill me with skepticism.