I'm not going to claim to be an expert here, but I think the relationship is a little different between Objective-J and JavaScript than between Objective-C and

I'm not going to claim to be an expert here, but I think the relationship is a little different between Objective-J and JavaScript than between Objective-C and C. The features of Objective-C pretty much across the board make operations simpler than they are in C. JavaScript already makes a lot of things pretty much as simple as it gets, and in some ways makes it too easy to accidentally do something wrong. So, Objective-J actually serves to impose a bit of structure on your code (and could even impose strict+static typing). That's basically how I've used it: Objective-J classes define the larger-scale architectural components of a project, but for smaller collections of data that are somehow related, especially for short-lived collections of data, I usually drop down to JavaScript and use the convenient hashes and arrays. Performance-wise, some operations will be faster in JavaScript than Objective-J, because things like message passing have an extra function call. I haven't found it to be a particularly noticeable difference, but admittedly I haven't been writing a lot of performance-critical code, so others might have better insights on that subject.