How to call functions from a regular JS file?

I’d like to use functions in a regular JS file, but how do I do that from an entity script ?
For now I just dragged and dropped the regular JS in my project, but I have no idea what code to write next.

Do you guys know ?

Here’s the script I’d like to use :

As you will be running the Javascript in a browser and not a Node.js environment, I think you can just remove the first 5 lines, add the script to the project as-is and the functions should be globally accessible.