Critical typo in javascript code (chapter #2)

[Vladislav Shkodin]

In the "Aliases & the Existential Operator" section there are two javascript code snippets:

if (typeof brian !== "undefined" && brian !== null) {
  praise;
}

and

var velocity;
velocity = typeof southern !== "undefined" && southern !== null ? southern : 40;

I think that "&&" operator is wrong, and there should be "||" instead.

[Vladislav Shkodin]

Oh, sorry, my fault... Somehow I didn't see that there is negation in if-condition.