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

The result of an expression using the comma operator is the right hand side of the comma operator.

You have:

return a_function_call(), a_string

… so you get a_string assigned.