JavaScript in IntelliJ rest client

I have read most if not all of the documentation JetBrains provides about their HTTP Client and how to create requests using files with .http extension.

My problem is that I want to use a function in a different .js file inside one of the .http request files. The way they explain how this can be achieved is with this 1 liner "For external scripts, you need to enable it manually." The problem is they don't explain how you do the manual part. I did find that you have add any custom js code/library via Settings-> Languages and Frameworks -> JavaScript -> Libraries.

So my question is if anyone knows how to import custom JavaScript in a different location in a .http file? My JavaScript function is written in this manner:

export default function writeResponse(response, client) { ... }