One extra example

Walkthrough: https://www.youtube.com/watch?v=tdB6kznA-ng

Feedback welcome.

Silly things:
* spacing
* single quotes vs double quotes

Minor things:
* javascript comments
* log statements
(do they make sense)

Relevant things:
* use of jQuery
(I can de-querify if you like)
Please also add a "key_exited" event callback here.