Looks like Symbols is a type being introduced because objects, when used as a key in another object, gets turned into a string, unlike Lua tables can be used as keys of other tables, and are guaranteed to not be equal to any other value. Lua tables are built-in symbols. Javascript's objects are not.
Yeah, it seems like kind of an odd choice to introduce a whole new type and extend the kind of values that can index an object, when extending object indexing alone would do everything symbols do anyway.
