Perhaps remind that for…in doesn't just use own properties?

[tdd]

Hi Nicholas,

Location: Chapter 4 > Page 76 > "Own property enumeration order" > Note

As the entire section is about own properties, as are Object.keys() and JSON.stringify(), I was wondering whether it would be useful to remind, when comparing them to for…in, that the latter also iterates over all enumerable props, not just own props?