Confusion about assignment with commas

Question

What is the logic behind the following code?

var next, output = null, thisNode;

It appears like it's some type of coalescing like var foo = bar || baz;, but I'm not so familiar with the commas.

Answer 1

multiple variable declarations.

its the same as this:

var next;
var output = null;
var thisNode;

Answer 2

It's just a shorter way of writing:

var next;
var output = null;
var thisNode;