C# access .js then I want the .js to access the C#

Hi, I have a .js that is accessed from a C# script so I placed my .js in plugins and all works fine, but I also want the .js to access the same C# script but is that possible because the .js is compiled first I get the error .. The name 'TestScript' does not denote a valid type ('not found'). I put the .js in plugins to compile first so the C# script can see it and access it, but when I put a ref (TestScript) in the .js to the C# script I get the error. Is this possible? Thanks.