[maxbucknell]

At the end of the article, it is demonstrated that this can happen even with strict equality by overriding the getters. Any language with getter/setter support can do this. Operator overloading can be used for even nefarious ends.

The point is that side effects in code are dangerous, and can be used to mislead a reader.

If this happens, it is not the fault of JavaScript. Anyone who writes code like that for purposes other than demonstration or learning is a moron.

[mikeash]

Not all languages with getter/setter support will invoke them automatically like this.

For example, it's not possible in Java or Objective-C to make an expression of the form a == b, where a and b are plain variables, have any side effects.

[tyilo]

In Obj-C you can if you would allow `a.prop == b.prop`.

[mikeash]

Sure, but then it's obvious that you're doing something beyond an equality comparison.

[jacalata]

Do you mean it is obvious to people who know objective C? I've never used the language, but its not obvious to me just from the other c-family languages I know.

[mikeash]

Yes, if you know Objective-C. If you don't know it, I wouldn't expect you to immediately grasp anything about the behavior implied by a snippet of it.