Considered harmful is a little excessive considering his analysis is that it's hard to test. Hard to read is very subjective (I find no issues with it). As for

Considered harmful is a little excessive considering his analysis is that it's hard to test. Hard to read is very subjective (I find no issues with it). As for extension, it's a pattern that is useful in some circumstances. It's not really something you would chose to use if you needed extension. I was going to say it was like saying a Singleton is harmful if you then change your mind later and decide you want multiple instances but I'm pretty sure I risk being called out for hyperbole. Generally though I find the notion of struggling to wedge privacy into JS code a waste of effort, there are much cleaner patterns. You are always relying on personal/group discipline and good habits when coding with JS anyway so why start by disadvantaging yourself.