I kinda have seen somewhere on internet, that the language design of lua and js(well, ecmascript to be precise) is somehow related. But can't really find the exact reference I have seen.. it was long time ago when I read this.
Now, the object systems do look similar, but that seems to be a case of convergent evolution: Javascript took direct inspiration from Self, whereas Lua's system is based on a more generic fallback mechanism for table access.