Author here. I actually walked through all of this code line by line in a conference talk using another thing I built: https://github.com/thejameskyle/spectacle-code-slide

I ripped these code comments from my presenter notes where I was explaining everything in case people couldn't read it.

I'll have to go back in and clean it up

Please DO NOT. You are right in your other comment that it helps with the flow and for example in the case of

   // We're going to create a `value` string that we are going to push
   // characters to.
   var value = '';

your comment declares you intention in advance, even if it might be trivial to deduce.

some people get really weird about comments.

in a case like this, i actually like the dialogue/conversation nature of the comments. i think the opinion of "not needing them" seems miss what they're accomplishing.

Comments about intention are good.

Yes, an experienced dev can infer intent from context (name, project, 'culture'), and even a smart beginner can read ahead to infer intent. But the comment resolves ambiguity in the advanced dev's mind, and saves the beginner's mind from the difficulty of read-ahead inferences (of which he may have several going at once).

I say, keep it.

I am someone who doesnt know much about compilers and I found them helpful. Setting up each variables purpose builds up context in my mind lessening the struggle with the 'real' code.