That doesn't seem right. Can you give an example? I use lots of js metaprogramming, but it mostly involves wrapping and passing functions, mixing in methods and dynamic getters etc. I don't think I've ever actually had to use eval, or anything eval-like.

OTOH, grep for instance_eval and class_eval in rails source.

Right, you should never ever use eval but I don't think that a lot of the things that are commonly done in Ruby could be achieved in JS without eval. And what you are talking about is not exactly meta-programming.

> OTOH, grep for instance_eval and class_eval in rails source.

I mean what's your point. Yes, I realize that both are used profusely, which is one of the things that this discussion is about.

> And what you are talking about is not exactly meta-programming.

I didn't describe metaprogramming, just how I usually see common metaprogramming "magic" implemented in javascript. The only reason you'd really need eval in js metaprogramming is if for some semantic reason it was nicer to accept a String of javascript somewhere. Afaik eval doesn't "get" you anything in javascript (it doesn't "unlock" private closures scope or anything, and context-injection is available using #call or #apply) and I almost never see it used, unless I am forgetting something (totally possible, I've been up all night)

> I mean what's your point. Yes, I realize that both are used profusely

My point is I don't see eval used profusely in javascript, which contradicts your assertion in a).

Edit: nvm, I stand corrected: (function(){var x = 1; eval('console.log(x)'); })() prints 1. Neat. But still, I do not see this often used, the callback + context passing approach is much more common.