Impossible JavaScript Question

test.js

/* what do each of these statements return?
   (assume that they are evaluated individually but in order.)
*/

const foo = 'asdf'; //=> ?

foo.bar = 12345; //=> ?

foo; //=> ?

foo.bar; //=> ?

Object.getOwnPropertyNames(foo); //=> ?

What's the use of knowing this? You wouldn't do it in production so who cares?

@EionRobb - I hadn't even thought about strict mode yet. Good catch!
@mgd020 - Shits and giggles lol. This actually came up because of production code so somebody did it in production.
@gkaykck - Haha. Well done ;). I absolutely don't expect people to know this stuff by heart. That's why it's such a weird challenge. This isn't stuff that you should know because you should never be doing this nonsense to begin with.