I knew it. And ?
It's good that you knew. But your post didn't indicate it, so other people reading your post would have no way of knowing.
When I said, "in case you didn't know," the 'you' is addressing anyone reading the post. I'm telling them where they can go to read more about the script and learn how it works and how to use it. It's a helpful pointer for people needing instructions.
I haven't ever wrote "this is my script".
By not writing, "this is someone else's script," the implication is that it's yours. It's always a good idea - and a matter of courtesy - to give credit where credit is due. The standard method for doing this with JavaScript is to name the author in a comment at the beginning of the script.