https://javascript.info/object
There are 3 minor things on that excellent page that I noticed being not quite right.

1. The term "figure brackets" is extremely rare in English usage, most people use the term that is used on MDN, "curly braces". Of course I know what you mean, but that term isn't one of the 3 or even 4 most popular terms for those characters { } so it is better not to teach it to people.
2. In the file cabinet analogy, calling the files "signed" is odd. The most common terms that don't have weird connotations would probably be "labelled" or "marked".
3. While it may be true in most or even all popular implementations, you are definitely not supposed to presume the order shown of the elements getting presented to you in a (for el in obj) loop. Other ways of retrieving them, yes, but not by for el in obj.