I find that what not to do is a harder lesson to learn than what should be done.
From my experience, what separates an expert from an intermediate is the ability to select from among various seemingly equivalent ways of doing the same thing.
So, when it comes to JavaScript what kinds of things should you not do and why?
I'm able to find lots of these for Java, but since JavaScript's typical context (in a browser) is very different from Java's I'm curious to see what comes out.