That’s a self executing anonymous function. It is self invoking. You don’t need to give it a name and call it later.
But this is advanced stuff, why did you start with it? It’s a bit mind warping. Take it slow , gradually from the simple stuff to the more difficult.
Look at ex11 in LJSTHW, Zed talks about anonymous functions and gives an example of one in a callback. Have you seen that video? He explains exactly that, watching it now (minute 18:36 on)
I was trying to make callbacks, see how they work, and I’m pretty sure I had the idea all wrong. You explain it in the video, I just didn’t pay enough attention the first time around.