[blurbytree]

There are only 3 things, which aren't surprising to anyone who has done much js.

  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() = ",,,"

[bonobo]

I don't think the comma operator wouldn't be surprising to an experienced js programmer. I can't remember a single piece of serious code where I could see it in use.

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.