You describe that as "not surprising"? Yikes.
Unsurprisingly, JavaScript is its own language.
1). a list of expressions eg (foo,bar,baz) evaluates to the last one.
2). Array(4) creates an empty array of 4 elements
2). Array(4).toString() = ",,,"The same applies to the void operator, I can think of one or two cases at most where it would be useful, but I don't see anyone using it.