For all those here mentioning that he's only "deconstructed" the snippet, and not the actual main linked analytics script, you're the first to observe that he's deconstructed the snippet incorrectly.

Don't get me wrong, it's really great and heartening to see someone new to JS getting back to basics and trying to understand things in proper minute detail (instead of doing another tutorial about a boilerplate React app), but this is hardly HN front-page material? It's a very simple JS snippet.