Coroutines, and Lua's metatables are more powerful than what can be done in ES5 (ES6 closes the gap a bit, and generators are equivalent to coroutines).

Lua is pretty much JS done right, which actually makes it a poor choice for something like this IMO. A program written in Lua is not going to be fundamentally different from the same program written in JS, and the problems introduced by using this (worse debugging experience etc.) are very likely to outweigh the benefits of avoiding JS's warts.