> “Unobtrusive JavaScript” is an decade-old technique I have already critized in an earlier article. JavaScript is considered “unobtrusive” when it adds additional behavior to an existing, self-sufficient HTML structure. Once the JavaScript kicks in, it changes the HTML DOM and adds behavior. Inevitably, this leads to significant content changes and reflows.

I completely agree with the author on the fact that this is a problem, but I don't understand blaming it on "unobtrusive javascript." Adding behavior doesn't require a reflow.