I didn't actually look at the implementation of these functions and tables, but yea, I am fairly familiar with Lua and metatables from my days of working on WoW addons.

As for JavaScript, my opinion is that Lua is everything JavaScript should have been: A clean, minimal, sanely designed, language. JavaScript on the other hand is nothing but mistakes piled upon mistakes. It's really disheartening to see JavaScript get shoved into places Lua fits better, like as Gnome Shell's scripting language. Oh well.