Why does this JavaScript work?

Question

I was looking at the output of some stuff from UglifyJS and happened across some code like the following:

var a = 0;
var b = function () {
    return functio         


        

Answer 1

It works due to the comma operator. From the MDN specs:

The comma operator evaluates both of its operands (from left to right) and returns the value of the second operand.

Both functions are IFFYs, they are inmediately executed.