The substance of the article is spot on, but I have to take issue with the terminology it uses. The problem he's talking about isn't classes, it's inheritance.

The substance of the article is spot on, but I have to take issue with the terminology it uses. The problem he's talking about isn't classes, it's inheritance. This is an important distinction. Javascript doesn't have classes, but it does have inheritance. The problems raganwald points out with the Account example come not from the organization of the code into pseudo-classes, but from the fact that it uses Javascript's inheritance mechanism. It would be perfectly possible to write a version of the example that exhibited the "fragile prototype problem," and conversely, one can easily write a version in Smalltalk that uses composition instead of inheritance and thus has no fragile base classes.