How to run KA JavaScript project code in an HTML file on GitHub?

Howdy. I'm not sure if this is the right section for postin' this thread, but ah heck, live and learn, I guess. :P

(I don't visit this here forum much, so I don't know what is what)

But anyways, I've been wantin' to know how to import or run JavaScript code into/in an HTML file on GitHub. I've attempted this a while back, but I couldn't get it to work. I figured someone else around here might be able to help.

This is what I got so far: https://github.com/DogToon64/Christmas-Zoroark-and-Pikachu