I do think the JS should be obligatory. Depending what you are doing, it can be an ambiguous term. For example, I'm working on some chef infrastructure where the word node refers to any top level attribute used by your cookbooks. There are also other people working with graph software where node has another definition.

I think the title was meant to read "why is" rather than "what is".

no, that's the name of the book.

So it is. Thank you for the correction.

Haha! +1